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Daneva Z, Chen Y, Ta HQ, Manchikalapudi V, Bazaz A, Laubach VE, Sonkusare SK. Endothelial IK and SK channel activation decreases pulmonary arterial pressure and vascular remodeling in pulmonary hypertension. Pulm Circ 2023; 13:e12186. [PMID: 36686408 PMCID: PMC9841469 DOI: 10.1002/pul2.12186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/20/2022] [Accepted: 12/29/2022] [Indexed: 01/09/2023] Open
Abstract
Endothelial cells (ECs) from small pulmonary arteries (PAs) release nitric oxide (NO) and prostacyclin, which lower pulmonary arterial pressure (PAP). In pulmonary hypertension (PH), the levels of endothelium-derived NO and prostacyclin are reduced, contributing to elevated PAP. Small-and intermediate-conductance Ca2+-activated K+ channels (IK and SK)-additional crucial endothelial mediators of vasodilation-are also present in small PAs, but their function has not been investigated in PH. We hypothesized that endothelial IK and SK channels can be targeted to lower PAP in PH. Whole-cell patch-clamp experiments showed functional IK and SK channels in ECs, but not smooth muscle cells, from small PAs. Using a SU5416 plus chronic hypoxia (Su + CH) mouse model of PH, we found that currents through EC IK and SK channels were unchanged compared with those from normal mice. Moreover, IK/SK channel-mediated dilation of small PAs was preserved in Su + CH mice. Consistent with previous reports, endothelial NO levels and NO-mediated dilation were reduced in small PAs from Su + CH mice. Notably, acute treatment with IK/SK channel activators decreased PAP in Su + CH mice but not in normal mice. Further, chronic activation of IK/SK channels decreased PA remodeling and right ventricular hypertrophy, which are pathological hallmarks of PH, in Su + CH mice. Collectively, our data provide the first evidence that, unlike endothelial NO release, IK/SK channel activity is not altered in PH. Our results also demonstrate proof of principle that IK/SK channel activation can be used as a strategy for lowering PAP in PH.
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Affiliation(s)
- Zdravka Daneva
- Robert M. Berne Cardiovascular Research CenterUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Yen‐Lin Chen
- Robert M. Berne Cardiovascular Research CenterUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Huy Q. Ta
- Department of SurgeryUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Vamsi Manchikalapudi
- Robert M. Berne Cardiovascular Research CenterUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Abhishek Bazaz
- Robert M. Berne Cardiovascular Research CenterUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Victor E. Laubach
- Department of SurgeryUniversity of VirginiaCharlottesvilleVirginiaUSA
| | - Swapnil K. Sonkusare
- Robert M. Berne Cardiovascular Research CenterUniversity of VirginiaCharlottesvilleVirginiaUSA,Department of Molecular Physiology and Biological PhysicsUniversity of VirginiaCharlottesvilleVirginiaUSA
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2
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Ca 2+-Activated K + Channels and the Regulation of the Uteroplacental Circulation. Int J Mol Sci 2023; 24:ijms24021349. [PMID: 36674858 PMCID: PMC9867535 DOI: 10.3390/ijms24021349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/13/2023] Open
Abstract
Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca2+-activated K+ (KCa) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. KCa channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by KCa channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of KCa channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.
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3
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Wulff H, Braun AP, Alper SL. Can KCa3.1 channel activators serve as novel inhibitors of platelet aggregation? J Thromb Haemost 2022; 20:2488-2490. [PMID: 36271464 DOI: 10.1111/jth.15863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 08/22/2022] [Indexed: 11/26/2022]
Affiliation(s)
- Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, California, USA
| | - Andrew P Braun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Seth L Alper
- Division of Nephrology and Vascular Biology Research Center, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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4
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Farquhar RE, Cheung TT, Logue MJE, McDonald FJ, Devor DC, Hamilton KL. Role of SNARE Proteins in the Insertion of KCa3.1 in the Plasma Membrane of a Polarized Epithelium. Front Physiol 2022; 13:905834. [PMID: 35832483 PMCID: PMC9271999 DOI: 10.3389/fphys.2022.905834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 06/01/2022] [Indexed: 11/29/2022] Open
Abstract
Targeting proteins to a specific membrane is crucial for proper epithelial cell function. KCa3.1, a calcium-activated, intermediate-conductance potassium channel, is targeted to the basolateral membrane (BLM) in epithelial cells. Surprisingly, the mechanism of KCa3.1 membrane targeting is poorly understood. We previously reported that targeting of KCa3.1 to the BLM of epithelial cells is Myosin-Vc-, Rab1-and Rab8-dependent. Here, we examine the role of the SNARE proteins VAMP3, SNAP-23 and syntaxin 4 (STX-4) in the targeting of KCa3.1 to the BLM of Fischer rat thyroid (FRT) epithelial cells. We carried out immunoblot, siRNA and Ussing chamber experiments on FRT cells, stably expressing KCa3.1-BLAP/Bir-A-KDEL, grown as high-resistance monolayers. siRNA-mediated knockdown of VAMP3 reduced BLM expression of KCa3.1 by 57 ± 5% (p ≤ 0.05, n = 5). Measurements of BLM-localized KCa3.1 currents, in Ussing chambers, demonstrated knockdown of VAMP3 reduced KCa3.1 current by 70 ± 4% (p ≤ 0.05, n = 5). Similarly, siRNA knockdown of SNAP-23 reduced the expression of KCa3.1 at the BLM by 56 ± 7% (p ≤ 0.01, n = 6) and reduced KCa3.1 current by 80 ± 11% (p ≤ 0.05, n = 6). Also, knockdown of STX-4 lowered the BLM expression of KCa3.1 by 54 ± 6% (p ≤ 0.05, n = 5) and reduced KCa3.1 current by 78 ± 11% (p ≤ 0.05, n = 5). Finally, co-immunoprecipitation experiments demonstrated associations between KCa3.1, VAMP3, SNAP-23 and STX-4. These data indicate that VAMP3, SNAP-23 and STX-4 are critical for the targeting KCa3.1 to BLM of polarized epithelial cells.
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Affiliation(s)
- Rachel E. Farquhar
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Tanya T. Cheung
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Matthew J. E. Logue
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Fiona J. McDonald
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Daniel C. Devor
- Department of Cell Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA, United States
| | - Kirk L. Hamilton
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- *Correspondence: Kirk L. Hamilton,
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5
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Kolski-Andreaco A, Balut CM, Bertuccio CA, Wilson AS, Rivers WM, Liu X, Gandley RE, Straub AC, Butterworth MB, Binion D, Devor DC. Histone deacetylase inhibitors (HDACi) increase expression of KCa2.3 (SK3) in primary microvascular endothelial cells. Am J Physiol Cell Physiol 2022; 322:C338-C353. [PMID: 35044858 PMCID: PMC8858676 DOI: 10.1152/ajpcell.00409.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The small conductance calcium-activated potassium channel (KCa2.3) has long been recognized for its role in mediating vasorelaxation through the endothelium-derived hyperpolarization (EDH) response. Histone deacetylases (HDACs) have been implicated as potential modulators of blood pressure and histone deacetylase inhibitors (HDACi) are being explored as therapeutics for hypertension. Herein, we show that HDACi increase KCa2.3 expression when heterologously expressed in HEK cells and endogenously expressed in primary cultures of human umbilical vein endothelial cells (HUVECs) and human intestinal microvascular endothelial cells (HIMECs). When primary endothelial cells were exposed to HDACi, KCa2.3 transcripts, subunits, and functional current are increased. Quantitative RT-PCR (qPCR) demonstrated increased KCa2.3 mRNA following HDACi, confirming transcriptional regulation of KCa2.3 by HDACs. By using pharmacological agents selective for different classes of HDACs, we discriminated between cytoplasmic and epigenetic modulation of KCa2.3. Biochemical analysis revealed an association between the cytoplasmic HDAC6 and KCa2.3 in immunoprecipitation studies. Specifically inhibiting HDAC6 increases expression of KCa2.3. In addition to increasing the expression of KCa2.3, we show that nonspecific inhibition of HDACs causes an increase in the expression of the molecular chaperone Hsp70 in endothelial cells. When Hsp70 is inhibited in the presence of HDACi, the magnitude of the increase in KCa2.3 expression is diminished. Finally, we show a slower rate of endocytosis of KCa2.3 as a result of exposure of primary endothelial cells to HDACi. These data provide the first demonstrated approach to increase KCa2.3 channel number in endothelial cells and may partially account for the mechanism by which HDACi induce vasorelaxation.
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Affiliation(s)
| | - Corina M. Balut
- 1Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | - Annette S. Wilson
- 2Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - William M. Rivers
- 2Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Xiaoning Liu
- 1Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robin E. Gandley
- 3Department of Obstetrics and Gynecology and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Adam C. Straub
- 4Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | - David Binion
- 2Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Daniel C. Devor
- 1Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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6
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Hansen FB, Secher N, Mattson T, Løfgren B, Simonsen U, Granfeldt A. Effect of the KCa3.1 blocker, senicapoc, on cerebral edema and cardiovascular function after cardiac arrest - A randomized experimental rat study. Resusc Plus 2021; 6:100111. [PMID: 34223371 PMCID: PMC8244250 DOI: 10.1016/j.resplu.2021.100111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/05/2021] [Accepted: 03/05/2021] [Indexed: 11/30/2022] Open
Abstract
Senicapoc was successfully administered intravenously. Senicapoc did not reduce cerebral edema 4 h after cardiac arrest. Senicapoc did not increase mean arterial pressure within 4 h from resuscitation.
Aim Formation of cerebral edema and cardiovascular dysfunction may worsen brain injury following cardiac arrest. We hypothesized that administration of the intermediate calcium-activated potassium (KCa3.1) channel blocker, senicapoc, would reduce cerebral edema and augment mean arterial pressure in the early post-resuscitation period. Method Male Sprague-Dawley rats, aged 11–15 weeks, were utilized in the study. Rats were exposed to 8 min of asphyxial cardiac arrest. Shortly after resuscitation, rats were randomized to receive either vehicle or senicapoc (10 mg/kg) intravenously. The primary outcome was cerebral wet to dry weight ratio 4 h after resuscitation. Secondary outcomes included mean arterial pressure, cardiac output, norepinephrine dose, inflammatory cytokines and neuron specific enolase levels. Additionally, a sub-study was conducted to validate intravenous administration of senicapoc. Results The sub-study revealed that senicapoc-treated rats maintained a significantly higher mean arterial pressure during administration of SKA-31 (a KCa3.1 channel opener). The plasma concentration of senicapoc was 1060 ± 303 ng/ml 4 h after administration. Senicapoc did not reduce cerebral edema or augment mean arterial pressure 4 h after resuscitation. Likewise, cardiac function and norepinephrine dose did not vary between groups. Inflammatory cytokines and neuron specific enolase levels increased in both groups after resuscitation with no difference between groups. Senicapoc enhanced the PaO2/FiO2 ratio significantly 4 h after resuscitation. Conclusion Senicapoc was successfully administered intravenously after resuscitation, but did not reduce cerebral edema or increase mean arterial pressure in the early post-resuscitation period.
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Affiliation(s)
- Frederik Boe Hansen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000 Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, 8200 Aarhus N, Denmark
| | - Niels Secher
- Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Palle Juul-Jensens Blvd. 99, 8200 Aarhus N, Denmark
| | - Thomas Mattson
- Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Palle Juul-Jensens Blvd. 99, 8200 Aarhus N, Denmark
| | - Bo Løfgren
- Department of Internal Medicine, Randers Regional Hospital, Skovlyvej 15, 8930 Randers NE, Denmark.,Research Center for Emergency Medicine, Aarhus University Hospital, Palle Juul-Jensens Blvd. 161, 8200 Aarhus N, Denmark
| | - Ulf Simonsen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000 Aarhus, Denmark
| | - Asger Granfeldt
- Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, 8200 Aarhus N, Denmark.,Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Palle Juul-Jensens Blvd. 99, 8200 Aarhus N, Denmark
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7
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Li X, Liu Y, Cao A, Li C, Wang L, Wu Q, Li X, Lv X, Zhu J, Chun H, Laba C, Du X, Zhang Y, Yang H. Crocin Improves Endothelial Mitochondrial Dysfunction via GPx1/ROS/KCa3.1 Signal Axis in Diabetes. Front Cell Dev Biol 2021; 9:651434. [PMID: 33777959 PMCID: PMC7994751 DOI: 10.3389/fcell.2021.651434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 02/10/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial dysfunction contributes to excessive reactive oxygen species (ROS) generation, which is a dramatic cause to promote endothelial dysfunction in diabetes. It was previously demonstrated that crocin protected the endothelium based on its diverse medicinal properties, but its effect on the mitochondrion and the potential mechanism are not fully understood. In this study, mitochondrial function was analyzed during the process of excessive ROS generation in high glucose (HG)-cultured human umbilical vein endothelial cells (HUVECs). The role played by KCa3.1 was further investigated by the inhibition and/or gene silence of KCa3.1 in this process. In addition, nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase 2 (NOX2), superoxide dismutase 1 (SOD1), and glutathione peroxidase 1 (GPx1) were also detected in this study. Our data showed that crocin improved mitochondrial dysfunction and maintained normal mitochondrial morphology by enhancing the mitochondrial membrane potential (MMP), mitochondrial mass, and mitochondrial fusion. Furthermore, KCa3.1 was confirmed to be located in the mitochondrion, and the blockade and/or silencing of KCa3.1 improved mitochondrial dysfunction and reduced excessive ROS generation but did not affect NOX2 and/or the SOD1 system. Intriguingly, it was confirmed that KCa3.1 expression was elevated by ROS overproduction in the endothelium under HG and/or diabetes conditions, while crocin significantly suppressed this elevation by promoting GPx1 and subsequently eliminating ROS generation. In addition, crocin enhanced CD31, thrombomodulin (TM), and p-/t-endothelial nitric oxide synthase (eNOS) expressions as well as NO generation and decreased vascular tone. Hence, crocin improved mitochondrial dysfunction through inhibiting ROS-induced KCa3.1 overexpression in the endothelium, which in turn reduced more ROS generation and final endothelial dysfunction in diabetes.
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Affiliation(s)
- Xuemei Li
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Yang Liu
- Department of Anatomy, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Anqiang Cao
- Department of Cardiac Surgery, The Third People's Hospital of Chengdu, Institute of Cardiovascular Science, Chengdu, China
| | - Chao Li
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Luodan Wang
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Qing Wu
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Xinlei Li
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Xiaohong Lv
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Jiwei Zhu
- Department of Forensic Medicine, Harbin Medical University, Harbin, China
| | - Hua Chun
- Department of Modern Medicine, Tibetan Traditional Medical College, Lhasa, China
| | - Ciren Laba
- Department of Modern Medicine, Tibetan Traditional Medical College, Lhasa, China
| | - Xingchi Du
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Yafang Zhang
- Department of Anatomy, Harbin Medical University, Harbin, China
| | - Huike Yang
- Department of Anatomy, Harbin Medical University, Harbin, China.,Department of Modern Medicine, Tibetan Traditional Medical College, Lhasa, China
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8
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Mishra RC, Kyle BD, Kendrick DJ, Svystonyuk D, Kieser TM, Fedak PWM, Wulff H, Braun AP. KCa channel activation normalizes endothelial function in Type 2 Diabetic resistance arteries by improving intracellular Ca 2+ mobilization. Metabolism 2021; 114:154390. [PMID: 33039407 PMCID: PMC7736096 DOI: 10.1016/j.metabol.2020.154390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Endothelial dysfunction is an early pathogenic event in the progression of cardiovascular disease in patients with Type 2 Diabetes (T2D). Endothelial KCa2.3 and KCa3.1 K+ channels are important regulators of arterial diameter, and we thus hypothesized that SKA-31, a small molecule activator of KCa2.3 and KCa3.1, would positively influence agonist-evoked dilation in myogenically active resistance arteries in T2D. METHODOLOGY Arterial pressure myography was utilized to investigate endothelium-dependent vasodilation in isolated cremaster skeletal muscle resistance arteries from 22 to 24 week old T2D Goto-Kakizaki rats, age-matched Wistar controls, and small human intra-thoracic resistance arteries from T2D subjects. Agonist stimulated changes in cytosolic free Ca2+ in acutely isolated, single endothelial cells from Wistar and T2D Goto-Kakizaki cremaster and cerebral arteries were examined using Fura-2 fluorescence imaging. MAIN FINDINGS Endothelium-dependent vasodilation in response to acetylcholine (ACh) or bradykinin (BK) was significantly impaired in isolated cremaster arteries from T2D Goto-Kakizaki rats compared with Wistar controls, and similar results were observed in human intra-thoracic arteries. In contrast, inhibition of myogenic tone by sodium nitroprusside, a direct smooth muscle relaxant, was unaltered in both rat and human T2D arteries. Treatment with a threshold concentration of SKA-31 (0.3 μM) significantly enhanced vasodilatory responses to ACh and BK in arteries from T2D Goto-Kakizaki rats and human subjects, whereas only modest effects were observed in non-diabetic arteries of both species. Mechanistically, SKA-31 enhancement of evoked dilation was independent of vascular NO synthase and COX activities. Remarkably, SKA-31 treatment improved agonist-stimulated Ca2+ elevation in acutely isolated endothelial cells from T2D Goto-Kakizaki cremaster and cerebral arteries, but not from Wistar control vessels. In contrast, SKA-31 treatment did not affect intracellular Ca2+ release by the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor cyclopiazonic acid. CONCLUSIONS Collectively, our data demonstrate that KCa channel modulation can acutely restore endothelium-dependent vasodilatory responses in T2D resistance arteries from rats and humans, which appears to involve improved endothelial Ca2+ mobilization.
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Affiliation(s)
- Ramesh C Mishra
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Barry D Kyle
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Dylan J Kendrick
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Daniyil Svystonyuk
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Teresa M Kieser
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Paul W M Fedak
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Heike Wulff
- Dept of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Andrew P Braun
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
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9
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Small and intermediate Ca2+-sensitive K+ channels do not play a role in vascular conductance during resting blood flow in the anaesthetised pig. Heart Vessels 2020; 35:284-289. [DOI: 10.1007/s00380-019-01489-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/23/2019] [Indexed: 10/26/2022]
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10
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John CM, Khaddaj Mallat R, Mishra RC, George G, Singh V, Turnbull JD, Umeshappa CS, Kendrick DJ, Kim T, Fauzi FM, Visser F, Fedak PWM, Wulff H, Braun AP. SKA-31, an activator of Ca 2+-activated K + channels, improves cardiovascular function in aging. Pharmacol Res 2019; 151:104539. [PMID: 31707036 DOI: 10.1016/j.phrs.2019.104539] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/22/2019] [Accepted: 11/06/2019] [Indexed: 12/16/2022]
Abstract
Aging represents an independent risk factor for the development of cardiovascular disease, and is associated with complex structural and functional alterations in the vasculature, such as endothelial dysfunction. Small- and intermediate-conductance, Ca2+-activated K+ channels (KCa2.3 and KCa3.1, respectively) are prominently expressed in the vascular endothelium, and pharmacological activators of these channels induce robust vasodilation upon acute exposure in isolated arteries and intact animals. However, the effects of prolonged in vivo administration of such compounds are unknown. In our study, we hypothesized that such treatment would ameliorate aging-related cardiovascular deficits. Aged (∼18 months) male Sprague Dawley rats were treated daily with either vehicle or the KCa channel activator SKA-31 (10 mg/kg, intraperitoneal injection; n = 6/group) for 8 weeks, followed by echocardiography, arterial pressure myography, immune cell and plasma cytokine characterization, and tissue histology. Our results show that SKA-31 administration improved endothelium-dependent vasodilation, reduced agonist-induced vascular contractility, and prevented the aging-associated declines in cardiac ejection fraction, stroke volume and fractional shortening, and further improved the expression of endothelial KCa channels and associated cell signalling components to levels similar to those observed in young male rats (∼5 months at end of study). SKA-31 administration did not promote pro-inflammatory changes in either T cell populations or plasma cytokines/chemokines, and we observed no overt tissue histopathology in heart, kidney, aorta, brain, liver and spleen. SKA-31 treatment in young rats had little to no effect on vascular reactivity, select protein expression, tissue histology, plasma cytokines/chemokines or immune cell properties. Collectively, these data demonstrate that administration of the KCa channel activator SKA-31 improved aging-related cardiovascular function, without adversely affecting the immune system or promoting tissue toxicity.
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Affiliation(s)
- Cini Mathew John
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Rayan Khaddaj Mallat
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Ramesh C Mishra
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Grace George
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Vikrant Singh
- Dept. of Pharmacology, University of California, Davis, USA
| | - Jeannine D Turnbull
- Dept. of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Channakeshava S Umeshappa
- Dept. of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Canada
| | - Dylan J Kendrick
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Taeyeob Kim
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Fazlin M Fauzi
- Dept. of Pharmacology and Chemistry, Universiti Teknologi MARA, Malaysia
| | - Frank Visser
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Paul W M Fedak
- Dept. of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada
| | - Heike Wulff
- Dept. of Pharmacology, University of California, Davis, USA
| | - Andrew P Braun
- Dept. of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Canada; Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Canada.
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11
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Kloza M, Baranowska-Kuczko M, Toczek M, Kusaczuk M, Sadowska O, Kasacka I, Kozłowska H. Modulation of Cardiovascular Function in Primary Hypertension in Rat by SKA-31, an Activator of KCa2.x and KCa3.1 Channels. Int J Mol Sci 2019; 20:ijms20174118. [PMID: 31450834 PMCID: PMC6747311 DOI: 10.3390/ijms20174118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/17/2019] [Accepted: 08/21/2019] [Indexed: 12/11/2022] Open
Abstract
The aim of this study was to investigate the hemodynamic effects of SKA-31, an activator of the small (KCa2.x) and intermediate (KCa3.1) conductance calcium-activated potassium channels, and to evaluate its influence on endothelium-derived hyperpolarization (EDH)-KCa2.3/KCa3.1 type relaxation in isolated endothelium-intact small mesenteric arteries (sMAs) from spontaneously hypertensive rats (SHRs). Functional in vivo and in vitro experiments were performed on SHRs or their normotensive controls, Wistar-Kyoto rats (WKY). SKA-31 (1, 3 and 10 mg/kg) caused a brief decrease in blood pressure and bradycardia in both SHR and WKY rats. In phenylephrine-pre-constricted sMAs of SHRs, SKA-31 (0.01–10 µM)-mediated relaxation was reduced and SKA-31 potentiated acetylcholine-evoked endothelium-dependent relaxation. Endothelium denudation and inhibition of nitric oxide synthase (eNOS) and cyclooxygenase (COX) by the respective inhibitors l-NAME or indomethacin, attenuated SKA-31-mediated vasorelaxation. The inhibition of KCa3.1, KCa2.3, KIR and Na+/K+-ATPase by TRAM-34, UCL1684, Ba2+ and ouabain, respectively, reduced the potency and efficacy of the EDH-response evoked by SKA-31. The mRNA expression of eNOS, prostacyclin synthase, KCa2.3, KCa3.1 and KIR were decreased, while Na+/K+-ATPase expression was increased. Collectively, SKA-31 promoted hypotension and vasodilatation, potentiated agonist-stimulated vasodilation, and maintained KCa2.3/KCa3.1-EDH-response in sMAs of SHR with downstream signaling that involved KIR and Na+/K+-ATPase channels. In view of the importance of the dysfunction of endothelium-mediated vasodilatation in the mechanism of hypertension, application of activators of KCa2.3/KCa3.1 channels such as SKA-31 seem to be a promising avenue in pharmacotherapy of hypertension.
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Affiliation(s)
- Monika Kloza
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Marta Baranowska-Kuczko
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
- Department of Clinical Pharmacy, Medical University of Białystok, 15-222 Białystok, Poland
| | - Marek Toczek
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Magdalena Kusaczuk
- Department of Pharmaceutical Biochemistry, Medical University of Białystok, 15-222 Białystok, Poland
| | - Olga Sadowska
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Irena Kasacka
- Department of Histology and Cytophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Hanna Kozłowska
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland.
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12
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Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
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13
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Khaddaj Mallat R, Mathew John C, Mishra RC, Kendrick DJ, Braun AP. Pharmacological Targeting of KCa Channels to Improve Endothelial Function in the Spontaneously Hypertensive Rat. Int J Mol Sci 2019; 20:ijms20143481. [PMID: 31315169 PMCID: PMC6678254 DOI: 10.3390/ijms20143481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 01/01/2023] Open
Abstract
Systemic hypertension is a major risk factor for the development of cardiovascular disease and is often associated with endothelial dysfunction. KCa2.3 and KCa3.1 channels are expressed in the vascular endothelium and contribute to stimulus-evoked vasodilation. We hypothesized that acute treatment with SKA-31, a selective activator of KCa2.x and KCa3.1 channels, would improve endothelium-dependent vasodilation and transiently lower mean arterial pressure (MAP) in male, spontaneously hypertensive rats (SHRs). Isolated vascular preparations exhibited impaired vasodilation in response to bradykinin (i.e., endothelial dysfunction) compared with Wistar controls, which was associated with decreased bradykinin receptor expression in mesenteric arteries. In contrast, similar levels of endothelial KCa channel expression were observed, and SKA-31 evoked vasodilation was comparable in vascular preparations from both strains. Addition of a low concentration of SKA-31 (i.e., 0.2–0.3 μM) failed to augment bradykinin-induced vasodilation in arteries from SHRs. However, responses to acetylcholine were enhanced. Surprisingly, acute bolus administration of SKA-31 in vivo (30 mg/kg, i.p. injection) modestly elevated MAP compared with vehicle injection. In summary, pharmacological targeting of endothelial KCa channels in SHRs did not readily reverse endothelial dysfunction in situ, or lower MAP in vivo. SHRs thus appear to be less responsive to endothelial KCa channel activators, which may be related to their vascular pathology.
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Affiliation(s)
- Rayan Khaddaj Mallat
- Department of Physiology and Pharmacology and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Cini Mathew John
- Department of Physiology and Pharmacology and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Ramesh C Mishra
- Department of Physiology and Pharmacology and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Dylan J Kendrick
- Department of Physiology and Pharmacology and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Andrew P Braun
- Department of Physiology and Pharmacology and Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
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SKA-31, an activator of endothelial Ca 2+-activated K + channels evokes robust vasodilation in rat mesenteric arteries. Eur J Pharmacol 2018; 831:60-67. [PMID: 29753043 DOI: 10.1016/j.ejphar.2018.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 12/17/2022]
Abstract
It is now well recognized that endothelial KCa2.3 and KCa3.1 channel activities contribute to dilation of resistance arteries via endothelium-mediated hyperpolarization and vascular smooth muscle relaxation. In this study, we have investigated the functional effect of the KCa channel activator SKA-31 in third order rat mesenteric arteries using arterial pressure myography. Isolated arteries were cannulated, pressurized intraluminally to 70 mmHg at 36 °C and then constricted with 1 μM phenylephrine. Acute bath exposure to SKA-31 evoked a robust and reversible inhibition of developed tone (IC50 = 0.22 μM). The vasodilatory effects of SKA-31 and acetylcholine were blunted in the presence of KCa2.3 and KCa3.1 channel antagonists, and were largely prevented following endothelial denudation. Western blot and q-PCR analyses of isolated mesenteric arteries revealed KCa2.3 and KCa3.1 channel expression at the protein and mRNA levels, respectively. Penitrem-A, an inhibitor of KCa1.1 channels, decreased vasodilatory responses to acetylcholine, sodium nitroprusside and NS-1619, but had little effect on SKA-31. Similarly, bath exposure to the eNOS inhibitor L-NAME did not alter SKA-31 and acetylcholine-mediated vasodilation. Collectively, these data highlight the major cellular mechanisms by which the endothelial KCa channel activator SKA-31 inhibits agonist-evoked vasoconstriction in rat small mesenteric arteries.
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15
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Behringer EJ. Calcium and electrical signaling in arterial endothelial tubes: New insights into cellular physiology and cardiovascular function. Microcirculation 2018; 24. [PMID: 27801542 DOI: 10.1111/micc.12328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022]
Abstract
The integral role of the endothelium during the coordination of blood flow throughout vascular resistance networks has been recognized for several decades now. Early examination of the distinct anatomy and physiology of the endothelium as a signaling conduit along the vascular wall has prompted development and application of an intact endothelial "tube" study model isolated from rodent skeletal muscle resistance arteries. Vasodilatory signals such as increased endothelial cell (EC) Ca2+ ([Ca2+ ]i ) and hyperpolarization take place in single ECs while shared between electrically coupled ECs through gap junctions up to distances of millimeters (≥2 mm). The small- and intermediate-conductance Ca2+ activated K+ (SKCa /IKCa or KCa 2.3/KCa 3.1) channels function at the interface of Ca2+ signaling and hyperpolarization; a bidirectional relationship whereby increases in [Ca2+ ]i activate SKCa /IKCa channels to produce hyperpolarization and vice versa. Further, the spatial domain of hyperpolarization among electrically coupled ECs can be finely tuned via incremental modulation of SKCa /IKCa channels to balance the strength of local and conducted electrical signals underlying vasomotor activity. Multifunctional properties of the voltage-insensitive SKCa /IKCa channels of resistance artery endothelium may be employed for therapy during the aging process and development of vascular disease.
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Affiliation(s)
- Erik J Behringer
- Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA
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Mathew John C, Khaddaj Mallat R, George G, Kim T, Mishra RC, Braun AP. Pharmacologic targeting of endothelial Ca 2+-activated K + channels: A strategy to improve cardiovascular function. Channels (Austin) 2018; 12:126-136. [PMID: 29577810 PMCID: PMC5972810 DOI: 10.1080/19336950.2018.1454814] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 03/15/2018] [Indexed: 12/17/2022] Open
Abstract
Endothelial small and intermediate-conductance, Ca2+-activated K+ channels (KCa2.3 and KCa3.1, respectively) play an important role in the regulation of vascular function and systemic blood pressure. Growing evidence indicates that they are intimately involved in agonist-evoked vasodilation of small resistance arteries throughout the circulation. Small molecule activators of KCa2.x and 3.1 channels, such as SKA-31, can acutely inhibit myogenic tone in isolated resistance arteries, induce effective vasodilation in intact vascular beds, such as the coronary circulation, and acutely decrease systemic blood pressure in vivo. The blood pressure-lowering effect of SKA-31, and early indications of improvement in endothelial dysfunction suggest that endothelial KCa channel activators could eventually be developed into a new class of endothelial targeted agents to combat hypertension or atherosclerosis. This review summarises recent insights into the activation of endothelial Ca2+ activated K+ channels in various vascular beds, and how tools, such as SKA-31, may be beneficial in disease-related conditions.
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Affiliation(s)
- Cini Mathew John
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Rayan Khaddaj Mallat
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Grace George
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Taeyeob Kim
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ramesh C. Mishra
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrew P. Braun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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17
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Structural insights into the potency of SK channel positive modulators. Sci Rep 2017; 7:17178. [PMID: 29214998 PMCID: PMC5719431 DOI: 10.1038/s41598-017-16607-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 11/15/2017] [Indexed: 12/26/2022] Open
Abstract
Small-conductance Ca2+-activated K+ (SK) channels play essential roles in the regulation of cellular excitability and have been implicated in neurological and cardiovascular diseases through both animal model studies and human genetic association studies. Over the past two decades, positive modulators of SK channels such as NS309 and 1-EBIO have been developed. Our previous structural studies have identified the binding pocket of 1-EBIO and NS309 that is located at the interface between the channel and calmodulin. In this study, we took advantage of four compounds with potencies varying over three orders of magnitude, including 1-EBIO, NS309, SKS-11 (6-bromo-5-methyl-1H-indole-2,3-dione-3-oxime) and SKS-14 (7-fluoro-3-(hydroxyimino)indolin-2-one). A combination of x-ray crystallographic, computational and electrophysiological approaches was utilized to investigate the interactions between the positive modulators and their binding pocket. A strong trend exists between the interaction energy of the compounds within their binding site calculated from the crystal structures, and the potency of these compounds in potentiating the SK2 channel current determined by electrophysiological recordings. Our results further reveal that the difference in potency of the positive modulators in potentiating SK2 channel activity may be attributed primarily to specific electrostatic interactions between the modulators and their binding pocket.
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18
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Khaddaj Mallat R, Mathew John C, Kendrick DJ, Braun AP. The vascular endothelium: A regulator of arterial tone and interface for the immune system. Crit Rev Clin Lab Sci 2017; 54:458-470. [PMID: 29084470 DOI: 10.1080/10408363.2017.1394267] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
As the primary interface between the blood and various tissues of the body, the vascular endothelium exhibits a diverse range of roles and activities, all of which contribute to the overall health and function of the cardiovascular system. In this focused review, we discuss several key aspects of endothelial function, how this may be compromised and subsequent consequences. Specifically, we examine the dynamic regulation of arterial contractility and distribution of blood flow through the generation of chemical and electrical signaling events that impinge upon vascular smooth muscle. The endothelium can generate a diverse range of vasoactive compounds and signals, most of which act locally to adjust blood flow in a dynamic fashion to match tissue metabolism. Disruption of these vascular signaling processes (e.g. reduced nitric oxide bioavailability) is typically referred to as endothelial dysfunction, which is a recognized risk factor for cardiovascular disease in patients and occurs early in the development and progression of hypertension, atherosclerosis and tissue ischemia. Endothelial dysfunction is also associated with type-2 Diabetes and aging and increased mechanistic knowledge of the cellular changes contributing to these effects may provide important clues for interventional strategies. The endothelium also serves as the initial site of interaction for immune cells entering tissues in response to damage and acts to facilitate the actions of both the innate and acquired immune systems to interact with the vascular wall. In addition to representing the main cell type responsible for the formation of new blood vessels (i.e. angiogenesis) within the vasculature, the endothelium is also emerging as a source of extracellular vesicle or microparticles for the transport of signaling molecules and other cellular materials to nearby, or remote, sites in the body. The characteristics of released microparticles appear to change with the functional status of the endothelium; thus, these microparticles may represent novel biomarkers of endothelial health and more serious cardiovascular disease.
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Affiliation(s)
- Rayan Khaddaj Mallat
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
| | - Cini Mathew John
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
| | - Dylan J Kendrick
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
| | - Andrew P Braun
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
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Comerma-Steffensen SG, Carvacho I, Hedegaard ER, Simonsen U. Small and Intermediate Calcium-Activated Potassium Channel Openers Improve Rat Endothelial and Erectile Function. Front Pharmacol 2017; 8:660. [PMID: 28993731 PMCID: PMC5619997 DOI: 10.3389/fphar.2017.00660] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/05/2017] [Indexed: 12/13/2022] Open
Abstract
Modulation of endothelial calcium-activated potassium (KCa) channels has been proposed as an approach to restore endothelial function. The present study investigated whether novel openers of KCa channels with small (KCa2.x) and intermediate (KCa3.1) conductance, NS309 and NS4591, improve endothelium-dependent relaxation and erectile function. Rat corpus cavernosum (CC) strips were mounted for isometric tension recording and processed for immunoblotting. Mean arterial pressure (MAP), intracavernosal pressure (ICP), and electrocardiographic (ECG) measurements were conducted in anesthetized rats. Immunoblotting revealed the presence of KCa2.3 and large KCa conductance (KCa1.1) channels in the corpus cavernosum. NS309 and NS4591 increased current in CC endothelial cells in whole cell patch clamp experiments. Relaxation induced by NS309 (<1 μM) was inhibited by endothelial cell removal and high extracellular potassium. An inhibitor of nitric oxide (NO) synthase, and blockers of KCa2.x and KCa1.1 channels, apamin and iberiotoxin also inhibited NS309 relaxation. Incubation with NS309 (0.5 μM) markedly enhanced acetylcholine relaxation. Basal erectile function (ICP/MAP) increased during administration of NS309. Increases in ICP/MAP after cavernous nerve stimulation with NS309 were unchanged, whereas NS4591 significantly improved erectile function. Administration of NS309 and NS4591 caused small changes in the electrocardiogram, but neither arrhythmic events nor prolongation of the QTc interval were observed. The present study suggests that openers of KCa2.x and KCa3.1 channels improve endothelial and erectile function. The effects of NS309 and NS4591 on heart rate and ECG are small, but will require additional safety studies before evaluating whether activation of KCa2.3 channels has a potential for treatment of erectile dysfunction.
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Affiliation(s)
- Simon G. Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
- Animal Physiology, Department of Biomedical Sciences, Veterinary Sciences Faculty, Central University of VenezuelaMaracay, Venezuela
| | - Ingrid Carvacho
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del MauleTalca, Chile
| | - Elise R. Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
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20
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Comerma-Steffensen S, Kun A, Hedegaard ER, Mogensen S, Aalkjaer C, Köhler R, Mønster Christensen B, Simonsen U. Down-regulation of K Ca2.3 channels causes erectile dysfunction in mice. Sci Rep 2017. [PMID: 28630432 PMCID: PMC5476588 DOI: 10.1038/s41598-017-04188-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Modulation of endothelial calcium-activated K+ channels has been proposed as an approach to restore arterial endothelial cell function in disease. We hypothesized that small-conductance calcium-activated K+ channels (KCa2.3 or SK3) contributes to erectile function. The research was performed in transgenic mice with overexpression (KCa2.3T/T(−Dox)) or down-regulation (KCa2.3T/T(+Dox)) of the KCa2.3 channels and wild-type C57BL/6-mice (WT). QPCR revealed that KCa2.3 and KCa1.1 channels were the most abundant in mouse corpus cavernosum. KCa2.3 channels were found by immunoreactivity and electron microscopy in the apical-lateral membrane of endothelial cells in the corpus cavernosum. Norepinephrine contraction was enhanced in the corpus cavernosum of KCa2.3T/T(+Dox)versus KCa2.3T/T(−Dox) mice, while acetylcholine relaxation was only reduced at 0.3 µM and relaxations in response to the nitric oxide donor sodium nitroprusside were unaltered. An opener of KCa2 channels, NS309 induced concentration-dependent relaxations of corpus cavernosum. Mean arterial pressure was lower in KCa2.3T/T(−Dox) mice compared with WT and KCa2.3T/T(+Dox) mice. In anesthetized mice, cavernous nerve stimulation augmented in frequency/voltage dependent manner erectile function being lower in KCa2.3T/T(+Dox) mice at low frequencies. Our findings suggest that down-regulation of KCa2.3 channels contributes to erectile dysfunction, and that pharmacological activation of KCa2.3 channels may have the potential to restore erectile function.
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Affiliation(s)
- Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.
| | - Attila Kun
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Elise R Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Susie Mogensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | | | - Ralf Köhler
- Aragon Agency for Investigation and Development (ARAID), Translational Research Unit, Miguel Servet University Hospital, Zaragoza, Spain
| | | | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
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Farquhar RE, Rodrigues E, Hamilton KL. The Role of the Cytoskeleton and Myosin-Vc in the Targeting of KCa3.1 to the Basolateral Membrane of Polarized Epithelial Cells. Front Physiol 2017; 7:639. [PMID: 28101059 PMCID: PMC5209343 DOI: 10.3389/fphys.2016.00639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 12/06/2016] [Indexed: 12/27/2022] Open
Abstract
Understanding the targeting of KCa3.1 to the basolateral membrane (BLM) of polarized epithelial cells is still emerging. Here, we examined the role of the cytoskeleton (microtubules and microfilaments) and Myosin-Vc (Myo-Vc) in the targeting of KCa3.1 in Fischer rat thyroid epithelial cells. We used a pharmacological approach with immunoblot (for the BLM expression of KCa3.1), Ussing chamber (functional BLM expression of KCa3.1) and siRNA experiments. The actin cytoskeleton inhibitors cytochalasin D (10 μM, 5 h) and latrunculin A (10 μM, 5 h) reduced the targeting of KCa3.1 to the BLM by 88 ± 4 and 70 ± 5%, respectively. Colchicine (10 μM, 5 h) a microtubule inhibitor reduced targeting of KCa3.1 to the BLM by 63 ± 7% and decreased 1-EBIO-stimulated KCa3.1 K+ current by 46 ± 18%, compared with control cells. ML9 (10 μM, 5 h), an inhibitor of myosin light chain kinase, decreased targeting of the channel by 83 ± 2% and reduced K+ current by 54 ± 8% compared to control cells. Inhibiting Myo-V with 2,3-butanedione monoxime (10 mM, 5 h) reduced targeting of the channel to the BLM by 58 ± 5% and decreased the stimulated current of KCa3.1 by 48 ± 12% compared with control cells. Finally, using siRNA for Myo-Vc, we demonstrated that knockdown of Myo-Vc reduced the BLM expression of KCa3.1 by 44 ± 7% and KCa3.1 K+ current by 1.04 ± 0.14 μA compared with control cells. These data suggest that the microtubule and microfilament cytoskeleton and Myo-Vc are critical for the targeting of KCa3.1.
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Affiliation(s)
- Rachel E Farquhar
- Department of Physiology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Ely Rodrigues
- Department of Medicine, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Kirk L Hamilton
- Department of Physiology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
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22
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Coleman HA, Tare M, Parkington HC. Nonlinear effects of potassium channel blockers on endothelium-dependent hyperpolarization. Acta Physiol (Oxf) 2017; 219:324-334. [PMID: 27639255 DOI: 10.1111/apha.12805] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/12/2016] [Accepted: 09/13/2016] [Indexed: 12/17/2022]
Abstract
In a number of published studies on endothelium-dependent hyperpolarization and relaxation, the results of the effects of K+ blockers have been difficult to interpret. When the effects of two blockers have been studied, often either blocker by itself had little effect, whereas the two blockers combined tended to abolish the responses. Explanations suggested in the literature include an unusual pharmacology of the K+ channels, and possible blocker binding interactions. In contrast, when we applied the same blockers to segments of small blood vessels under voltage clamp, the blockers reduced the endothelium-dependent K+ current in a linearly additive manner. Resolution of these contrasting results is important as endothelium-derived hyperpolarization (EDH) makes its greatest contribution to vasorelaxation in arterioles and small resistance arteries, where it can exert a significant role in tissue perfusion and blood pressure regulation. Furthermore, EDH is impaired in various diseases. Here, we consider why the voltage-clamp results differ from earlier free-running membrane potential and contractility studies. We fitted voltage-clamp-derived current-voltage relationships with mathematical functions and considered theoretically the effects of partial and total block of endothelium-derived K+ -currents on the membrane potential of small blood vessels. When the K+ -conductance was partially reduced, equivalent to applying a single blocker, the effect on EDH was small. Total block of the endothelium-dependent K+ conductance abolished the hyperpolarization, in agreement with various published studies. We conclude that nonlinear summation of the hyperpolarizing response evoked by endothelial stimulation can explain the variable effectiveness of individual K+ channel blockers on endothelium-dependent hyperpolarization and resulting relaxation.
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Affiliation(s)
- H. A. Coleman
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - M. Tare
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
| | - H. C. Parkington
- Department of Physiology; Biomedicine Discovery Institute; Cardiovascular Disease Program; Monash University; Clayton Vic. Australia
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Garland CJ, Dora KA. EDH: endothelium-dependent hyperpolarization and microvascular signalling. Acta Physiol (Oxf) 2017; 219:152-161. [PMID: 26752699 DOI: 10.1111/apha.12649] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 11/04/2015] [Accepted: 01/06/2016] [Indexed: 12/31/2022]
Abstract
Endothelium-dependent hyperpolarizing factor (EDHF) is a powerful vasodilator influence in small resistance arteries and thus an important modulator of blood pressure and flow. As the name suggests, EDHF was thought to describe a diffusible factor stimulating smooth muscle hyperpolarization (and thus vasodilatation). However, this idea has evolved with the recognition that a factor can operate alongside the spread of hyperpolarizing current from the endothelium to the vascular smooth muscle (VSM). As such, the pathway is now termed endothelium-dependent hyperpolarization (EDH). EDH is activated by an increase in endothelial [Ca2+ ]i , which stimulates two Ca2+ -sensitive K channels, SKCa and IKCa . This was discovered because apamin and charybdotoxin applied in combination blocked EDHF responses, but iberiotoxin - a blocker of BKCa - was not able to substitute for charybdotoxin. SKCa and IKCa channels are arranged in endothelial microdomains, particularly within projections towards the adjacent smooth muscle, which are rich in IKCa channels and close to interendothelial gap junctions where SKCa channels, are prevalent. KCa activation hyperpolarizes endothelial cells, and K+ efflux through them can act as a diffusible 'EDHF' by stimulating VSM Na+ ,K+ -ATPase and inwardly rectifying K channels (KIR ). In parallel, hyperpolarizing current spreads from the endothelium to the smooth muscle through myoendothelial gap junctions located on endothelial projections. The resulting radial EDH is complemented by the spread of 'conducted' hyperpolarization along the endothelium of arteries and arterioles to affect conducted vasodilatation (CVD). Retrograde CVD effectively integrates blood flow within the microcirculation, but how the underlying hyperpolarization is sustained is unclear.
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Affiliation(s)
- C. J. Garland
- Department of Pharmacology; University of Oxford; Oxford UK
| | - K. A. Dora
- Department of Pharmacology; University of Oxford; Oxford UK
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24
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Sevelsted Møller L, Fialla AD, Schierwagen R, Biagini M, Liedtke C, Laleman W, Klein S, Reul W, Koch Hansen L, Rabjerg M, Singh V, Surra J, Osada J, Reinehr R, de Muckadell OBS, Köhler R, Trebicka J. The calcium-activated potassium channel KCa3.1 is an important modulator of hepatic injury. Sci Rep 2016; 6:28770. [PMID: 27354175 PMCID: PMC4926059 DOI: 10.1038/srep28770] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/10/2016] [Indexed: 12/12/2022] Open
Abstract
The calcium-activated potassium channel KCa3.1 controls different cellular processes such as proliferation and volume homeostasis. We investigated the role of KCa3.1 in experimental and human liver fibrosis. KCa3.1 gene expression was investigated in healthy and injured human and rodent liver. Effect of genetic depletion and pharmacological inhibition of KCa3.1 was evaluated in mice during carbon tetrachloride induced hepatic fibrogenesis. Transcription, protein expression and localisation of KCa3.1 was analysed by reverse transcription polymerase chain reaction, Western blot and immunohistochemistry. Hemodynamic effects of KCa3.1 inhibition were investigated in bile duct-ligated and carbon tetrachloride intoxicated rats. In vitro experiments were performed in rat hepatic stellate cells and hepatocytes. KCa3.1 expression was increased in rodent and human liver fibrosis and was predominantly observed in the hepatocytes. Inhibition of KCa3.1 aggravated liver fibrosis during carbon tetrachloride challenge but did not change hemodynamic parameters in portal hypertensive rats. In vitro, KCa3.1 inhibition leads to increased hepatocyte apoptosis and DNA damage, whereas proliferation of hepatic stellate cells was stimulated by KCa3.1 inhibition. Our data identifies KCa3.1 channels as important modulators in hepatocellular homeostasis. In contrast to previous studies in vitro and other tissues this channel appears to be anti-fibrotic and protective during liver injury.
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Affiliation(s)
- Linda Sevelsted Møller
- Department of Medical Gastroenterology and Hepatology, Odense University Hospital, Odense, Denmark.,Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Annette Dam Fialla
- Department of Medical Gastroenterology and Hepatology, Odense University Hospital, Odense, Denmark
| | | | - Matteo Biagini
- Department of Pathology, Odense University Hospital, Odense, Denmark
| | - Christian Liedtke
- Department of Internal Medicine III, University Hospital RWTH Aachen, Aachen, Germany
| | - Wim Laleman
- Department of Liver and Biliopancreatic disorders, University of Leuven, Leuven, Belgium
| | - Sabine Klein
- Department of Internal Medicine I, University of Bonn, Bonn, Germany
| | - Winfried Reul
- Department of Internal Medicine I, University of Bonn, Bonn, Germany
| | - Lars Koch Hansen
- Department of Medical Gastroenterology and Hepatology, Vejle Hospital, Vejle, Denmark
| | - Maj Rabjerg
- Department of Pathology, Odense University Hospital, Odense, Denmark
| | - Vikrant Singh
- Department of Pharmacology, University of California, Davis, California, USA
| | - Joaquin Surra
- Departament de Producción Animal, Escuela Politécnica Superior, Huesca, Spain
| | - Jesus Osada
- Departamento Bioquímica y Biología Molecular y Celular, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza-CIBEROBN, Zaragoza, Spain
| | - Roland Reinehr
- Elbe-Elster Klinikum, Krankenhaus Herzberg, Herzberg, Germany
| | | | - Ralf Köhler
- Aragon Institute of Health Science I CS, Zaragoza, Spain
| | - Jonel Trebicka
- Department of Medical Gastroenterology and Hepatology, Odense University Hospital, Odense, Denmark.,Department of Internal Medicine I, University of Bonn, Bonn, Germany
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25
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26
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Yap FC, Weber DS, Taylor MS, Townsley MI, Comer BS, Maylie J, Adelman JP, Lin MT. Endothelial SK3 channel-associated Ca2+ microdomains modulate blood pressure. Am J Physiol Heart Circ Physiol 2016; 310:H1151-63. [PMID: 26945080 DOI: 10.1152/ajpheart.00787.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 02/22/2016] [Indexed: 11/22/2022]
Abstract
Activation of vascular endothelial small- (KCa2.3, SK3) or intermediate- (KCa3.1, IK1) conductance Ca(2+)-activated potassium channels induces vasorelaxation via an endothelium-derived hyperpolarization (EDH) pathway. Although the activation of SK3 and IK1 channels converges on EDH, their subcellular effects on signal transduction are different and not completely clear. In this study, a novel endothelium-specific SK3 knockout (SK3(-/-)) mouse model was utilized to specifically examine the contribution of SK3 channels to mesenteric artery vasorelaxation, endothelial Ca(2+) dynamics, and blood pressure. The absence of SK3 expression was confirmed using real-time quantitative PCR and Western blot analysis. Functional studies showed impaired EDH-mediated vasorelaxation in SK3(-/-) small mesenteric arteries. Immunostaining results from SK3(-/-) vessels confirmed the absence of SK3 and further showed altered distribution of transient receptor potential channels, type 4 (TRPV4). Electrophysiological recordings showed a lack of SK3 channel activity, while TRPV4-IK1 channel coupling remained intact in SK3(-/-) endothelial cells. Moreover, Ca(2+) imaging studies in SK3(-/-) endothelium showed increased Ca(2+) transients with reduced amplitude and duration under basal conditions. Importantly, SK3(-/-) endothelium lacked a distinct type of Ca(2+) dynamic that is sensitive to TRPV4 activation. Blood pressure measurements showed that the SK3(-/-) mice were hypertensive, and the blood pressure increase was further enhanced during the 12-h dark cycle when animals are most active. Taken together, our results reveal a previously unappreciated SK3 signaling microdomain that modulates endothelial Ca(2+) dynamics, vascular tone, and blood pressure.
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Affiliation(s)
- Fui C Yap
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama
| | - David S Weber
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama
| | - Mark S Taylor
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama
| | - Mary I Townsley
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama
| | - Brian S Comer
- Department of Cellular and Integrative Physiology, Indiana University, Indianapolis, Indiana
| | - James Maylie
- Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon; and
| | - John P Adelman
- Vollum Institute, Oregon Health & Science University, Portland, Oregon
| | - Mike T Lin
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama;
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27
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Oliván-Viguera A, Valero MS, Pinilla E, Amor S, García-Villalón ÁL, Coleman N, Laría C, Calvín-Tienza V, García-Otín ÁL, Fernández-Fernández JM, Murillo MD, Gálvez JA, Díaz-de-Villegas MD, Badorrey R, Simonsen U, Rivera L, Wulff H, Köhler R. Vascular Reactivity Profile of Novel KCa 3.1-Selective Positive-Gating Modulators in the Coronary Vascular Bed. Basic Clin Pharmacol Toxicol 2016; 119:184-92. [PMID: 26821335 DOI: 10.1111/bcpt.12560] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 01/17/2016] [Indexed: 12/12/2022]
Abstract
Opening of intermediate-conductance calcium-activated potassium channels (KC a 3.1) produces membrane hyperpolarization in the vascular endothelium. Here, we studied the ability of two new KC a 3.1-selective positive-gating modulators, SKA-111 and SKA-121, to (1) evoke porcine endothelial cell KC a 3.1 membrane hyperpolarization, (2) induce endothelium-dependent and, particularly, endothelium-derived hyperpolarization (EDH)-type relaxation in porcine coronary arteries (PCA) and (3) influence coronary artery tone in isolated rat hearts. In whole-cell patch-clamp experiments on endothelial cells of PCA (PCAEC), KC a currents evoked by bradykinin (BK) were potentiated ≈7-fold by either SKA-111 or SKA-121 (both at 1 μM) and were blocked by a KC a 3.1 blocker, TRAM-34. In membrane potential measurements, SKA-111 and SKA-121 augmented bradykinin-induced hyperpolarization. Isometric tension measurements in large- and small-calibre PCA showed that SKA-111 and SKA-121 potentiated endothelium-dependent relaxation with intact NO synthesis and EDH-type relaxation to BK by ≈2-fold. Potentiation of the BK response was prevented by KC a 3.1 inhibition. In Langendorff-perfused rat hearts, SKA-111 potentiated coronary vasodilation elicited by BK. In conclusion, our data show that positive-gating modulation of KC a 3.1 channels improves BK-induced membrane hyperpolarization and endothelium-dependent relaxation in small and large PCA as well as in the coronary circulation of rats. Positive-gating modulators of KC a 3.1 could be therapeutically useful to improve coronary blood flow and counteract impaired coronary endothelial dysfunction in cardiovascular disease.
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Affiliation(s)
| | - Marta Sofía Valero
- Department of Pharmacy, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain
| | - Estéfano Pinilla
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Sara Amor
- Department of Physiology, Faculty of Medicine, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Nichole Coleman
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Celia Laría
- Department of Pharmacy, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain
| | - Víctor Calvín-Tienza
- Department of Pharmacy, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain
| | - Ángel-Luis García-Otín
- Department of Pharmacy, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain
| | - José M Fernández-Fernández
- Laboratori de Fisiologia Molecular i Canalopaties, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain
| | - M Divina Murillo
- Department of Pharmacology and Physiology, Veterinary Faculty, University of Zaragoza, Zaragoza, Spain
| | - José A Gálvez
- Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Zaragoza, Spain
| | - María D Díaz-de-Villegas
- Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Zaragoza, Spain
| | - Ramón Badorrey
- Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC - Universidad de Zaragoza, Zaragoza, Spain
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Luis Rivera
- Department of Physiology, Faculty of Pharmacy, Universidad Complutense de Madrid, Madrid, Spain
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Ralf Köhler
- Aragon Institute of Health Sciences & IIS, Zaragoza, Spain.,Aragon Agency for Research and Development (ARAID), Zaragoza, Spain
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28
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Köhler R, Oliván-Viguera A, Wulff H. Endothelial Small- and Intermediate-Conductance K Channels and Endothelium-Dependent Hyperpolarization as Drug Targets in Cardiovascular Disease. ADVANCES IN PHARMACOLOGY 2016; 77:65-104. [DOI: 10.1016/bs.apha.2016.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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29
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Calcium-Activated Potassium Channels: Potential Target for Cardiovascular Diseases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:233-261. [PMID: 27038376 DOI: 10.1016/bs.apcsb.2015.11.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ca(2+)-activated K(+) channels (KCa) are classified into three subtypes: big conductance (BKCa), intermediate conductance (IKCa), and small conductance (SKCa) KCa channels. The three types of KCa channels have distinct physiological or pathological functions in cardiovascular system. BKCa channels are mainly expressed in vascular smooth muscle cells (VSMCs) and inner mitochondrial membrane of cardiomyocytes, activation of BKCa channels in these locations results in vasodilation and cardioprotection against cardiac ischemia. IKCa channels are expressed in VSMCs, endothelial cells, and cardiac fibroblasts and involved in vascular smooth muscle proliferation, migration, vessel dilation, and cardiac fibrosis. SKCa channels are widely expressed in nervous and cardiovascular system, and activation of SKCa channels mainly contributes membrane hyperpolarization. In this chapter, we summarize the physiological and pathological roles of the three types of KCa channels in cardiovascular system and put forward the possibility of KCa channels as potential target for cardiovascular diseases.
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30
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Behringer EJ, Segal SS. Membrane potential governs calcium influx into microvascular endothelium: integral role for muscarinic receptor activation. J Physiol 2015; 593:4531-48. [PMID: 26260126 DOI: 10.1113/jp271102] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/03/2015] [Indexed: 01/12/2023] Open
Abstract
In resistance arteries, coupling a rise of intracellular calcium concentration ([Ca(2+)]i) to endothelial cell hyperpolarization underlies smooth muscle cell relaxation and vasodilatation, thereby increasing tissue blood flow and oxygen delivery. A controversy persists as to whether changes in membrane potential (V(m)) alter endothelial cell [Ca(2+)]i. We tested the hypothesis that V(m) governs [Ca(2+)]i in endothelium of resistance arteries by performing Fura-2 photometry while recording and controlling V(m) of intact endothelial tubes freshly isolated from superior epigastric arteries of C57BL/6 mice. Under resting conditions, [Ca(2+)]i did not change when V(m) shifted from baseline (∼-40 mV) via exposure to 10 μM NS309 (hyperpolarization to ∼-80 mV), via equilibration with 145 mm [K(+)]o (depolarization to ∼-5 mV), or during intracellular current injection (±0.5 to 5 nA, 20 s pulses) while V(m) changed linearly between ∼-80 mV and +10 mV. In contrast, during the plateau (i.e. Ca(2+) influx) phase of the [Ca(2+)]i response to approximately half-maximal stimulation with 100 nm ACh (∼EC50), [Ca(2+)]i increased as V(m) hyperpolarized below -40 mV and decreased as V(m) depolarized above -40 mV. The magnitude of [Ca(2+)]i reduction during depolarizing current injections correlated with the amplitude of the plateau [Ca(2+)]i response to ACh. The effect of hyperpolarization on [Ca(2+)]i was abolished following removal of extracellular Ca(2+), was enhanced subtly by raising extracellular [Ca(2+)] from 2 mm to 10 mm and was reduced by half in endothelium of TRPV4(-/-) mice. Thus, during submaximal activation of muscarinic receptors, V(m) can modulate Ca(2+) entry through the plasma membrane in accord with the electrochemical driving force.
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Affiliation(s)
- Erik J Behringer
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, 65212, USA
| | - Steven S Segal
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, 65212, USA.,Dalton Cardiovascular Research Center, Columbia, MO, 65211, USA
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31
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Mishra RC, Mitchell JR, Gibbons-Kroeker C, Wulff H, Belenkie I, Tyberg JV, Braun AP. A pharmacologic activator of endothelial KCa channels increases systemic conductance and reduces arterial pressure in an anesthetized pig model. Vascul Pharmacol 2015; 79:24-31. [PMID: 26239885 DOI: 10.1016/j.vph.2015.07.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 11/27/2022]
Abstract
SKA-31, an activator of endothelial KCa2.3 and KCa3.1 channels, reduces systemic blood pressure in mice and dogs, however, its effects in larger mammals are not well known. We therefore examined the hemodynamic effects of SKA-31, along with sodium nitroprusside (SNP), in anesthetized, juvenile male domestic pigs. Experimentally, continuous measurements of left ventricular (LV), aortic and inferior vena cava (IVC) pressures, along with flows in the ascending aorta, carotid artery, left anterior descending coronary artery and renal artery, were performed during acute administration of SKA-31 (0.1, 0.3, 1.0, 3.0 and 5.0mg/ml/kg) and a single dose of SNP (5.0 μg/ml/kg). SKA-31 dose-dependently reduced mean aortic pressure (mPAO), with the highest dose decreasing mPAO to a similar extent as SNP (-23 ± 3 and -28 ± 4 mmHg, respectively). IVC pressure did not change. Systemic conductance and conductance in coronary and carotid arteries increased in response to SKA-31 and SNP, but renal artery conductance was unaffected. There was no change in either LV stroke volume (SV) or heart rate (versus the preceding control) for any infusion. With no change in SV, drug-evoked decreases in LV stroke work (SW) were attributed to reductions in mPAO (SW vs. mPAO, r(2)=0.82, P<0.001). In summary, SKA-31 dose-dependently reduced mPAO by increasing systemic and arterial conductances. Primary reductions in mPAO by SKA-31 largely account for associated decreases in SW, implying that SKA-31 does not directly impair cardiac contractility.
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Affiliation(s)
- Ramesh C Mishra
- Dept. of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Jamie R Mitchell
- Dept of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Carol Gibbons-Kroeker
- Dept. of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Dept. of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada; Dept. of Biology, Ambrose University College, Calgary, Alberta, Canada
| | - Heike Wulff
- Dept. of Pharmacology, University of California Davis, Davis, CA, USA
| | - Israel Belenkie
- Dept. of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Dept. of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - John V Tyberg
- Dept. of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Dept. of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Andrew P Braun
- Dept. of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
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Christophersen P, Wulff H. Pharmacological gating modulation of small- and intermediate-conductance Ca(2+)-activated K(+) channels (KCa2.x and KCa3.1). Channels (Austin) 2015. [PMID: 26217968 DOI: 10.1080/19336950.2015.1071748] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
This short review discusses pharmacological modulation of the opening/closing properties (gating) of small- and intermediate-conductance Ca(2+)-activated K(+) channels (KCa2 and KCa3.1) with special focus on mechanisms-of-action, selectivity, binding sites, and therapeutic potentials. Despite KCa channel gating-modulation being a relatively novel field in drug discovery, efforts in this area have already revealed a surprising plethora of pharmacological sites-of-actions and channel subtype selectivity exerted by different chemical classes. The currently published positive modulators show that such molecules are potentially useful for the treatment of various neurodegenerative disorders such as ataxia, alcohol dependence, and epilepsy as well as hypertension. The negative KCa2 modulators are very effective agents for atrial fibrillation. The prediction is that further unraveling of the molecular details of gating pharmacology will allow for the design of even more potent and subtype selective KCa modulators entering into drug development for these indications.
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Affiliation(s)
| | - Heike Wulff
- b Department of Pharmacology ; University of California, Davis ; Davis , CA USA
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33
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Toussaint F, Charbel C, Blanchette A, Ledoux J. CaMKII regulates intracellular Ca²⁺ dynamics in native endothelial cells. Cell Calcium 2015; 58:275-85. [PMID: 26100947 DOI: 10.1016/j.ceca.2015.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 05/15/2015] [Accepted: 06/06/2015] [Indexed: 01/11/2023]
Abstract
Localized endothelial Ca(2+) signalling, such as Ca(2+) pulsars, can modulate the contractile state of the underlying vascular smooth muscle cell through specific endothelial targets. In addition to K(Ca)3.1 as a target, Ca(2+) pulsars, an IP3R-dependent pulsatile Ca(2+) release from the endoplasmic reticulum (ER) could activate a frequency-sensitive Ca(2+)-dependent kinase such as CaMKII. In the absence of extracellular Ca(2+), acetylcholine increased endothelial CaMKII phosphorylation and activation, thereby suggesting CaMKII activation independently of Ca(2+) influx. Herein, a reciprocal relation where CaMKII controls endothelial Ca(2+) dynamics has been investigated in mesenteric arteries. Both CaMKIIα and β isoforms have been identified in endothelial cells and close proximity (<40 nm) suggests their association in heteromultimers. Intracellular Ca(2+) monitoring with high speed confocal microscopy then showed that inhibition of CaMKII with KN-93 significantly increased the population of Ca(2+) pulsars active sites (+89%), suggesting CaMKII as a major regulator of Ca(2+) pulsars in native endothelium. Mechanistic insights were then sought through the elucidation of the impact of CaMKII on ER Ca(2+) store. ER Ca(2+) emptying was accelerated by CaMKII inhibition and ER Ca(2+) content was assessed using ionomycin. Exposure to KN-93 strongly diminished ER Ca(2+) content (-61%) by relieving CaMKII-dependent inhibition of IP3 receptors (IP3R). Moreover, in situ proximity ligation assay suggested CaMKII-IP3R promiscuity, essential condition for a protein-protein interaction. Interestingly, segregation of IP3R within myoendothelial projection (MEP) appears to be isoform-specific. Hence, only IP3R type 1 and type 2 are detected within fenestrations of the internal elastic lamina, sites of MEP, whilst type 3 is absent from these structures. In summary, CaMKII seems to act as a Ca(2+)-sensitive switch of a negative feedback loop regulating endothelial Ca(2+) homeostasis, including Ca(2+) pulsars.
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Affiliation(s)
- Fanny Toussaint
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Physiology, Université de Montréal, Québec, Canada
| | - Chimène Charbel
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Pharmacology, Université de Montréal, Québec, Canada
| | | | - Jonathan Ledoux
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Physiology, Université de Montréal, Québec, Canada; Department of Pharmacology, Université de Montréal, Québec, Canada; Department of Medicine, Université de Montréal, Québec, Canada.
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34
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More AS, Mishra JS, Hankins GDV, Yallampalli C, Sathishkumar K. Enalapril Normalizes Endothelium-Derived Hyperpolarizing Factor-Mediated Relaxation in Mesenteric Artery of Adult Hypertensive Rats Prenatally Exposed to Testosterone. Biol Reprod 2015; 92:155. [PMID: 25972013 DOI: 10.1095/biolreprod.115.130468] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/07/2015] [Indexed: 12/19/2022] Open
Abstract
Prenatal exposure to elevated testosterone levels induces adult life hypertension associated with selective impairments in endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation in mesenteric arteries. We tested whether the angiotensin-converting enzyme inhibitor enalapril restores EDHF function through regulating the activities of small (Kcnn3) and intermediate (Kcnn4) conductance calcium-activated potassium channels in mesenteric arteries. Pregnant Sprague-Dawley rats were injected subcutaneously with vehicle or testosterone propionate (0.5 mg/kg/day from Gestation Day 15 to 19), and their 6-mo-old adult male offspring were examined. A subset of rats in these two groups was given enalapril (40 mg/kg/day) for 2 wk through drinking water. Blood pressures were assessed through carotid arterial catheter and endothelium-dependent mesenteric arterial EDHF relaxation, using wire myography. Ace and Kcnn3 and Kcnn4 channel expression levels were also examined. Renal and vascular Ace expression and plasma angiotensin II levels were increased in testosterone offspring. Blood pressure levels were significantly higher in testosterone offspring than in controls, and treatment with enalapril significantly attenuated blood pressure in testosterone offspring. EDHF relaxation in testosterone offspring was reduced compared to that in controls, and it was significantly restored by enalapril treatment. Kcnn4 channel expression and function were similar between control and testosterone rats, but it was not affected by enalapril treatment. Relaxation mediated by Kcnn3 was impaired in testosterone offspring, and it was normalized by enalapril treatment. Furthermore, enalapril treatment restored expression levels of Kcnn3 channels. These findings suggest that enalapril has a positive influence on endothelial function with improvement in EDHF relaxation through normalization of Kcnn3 expression and activity.
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Affiliation(s)
- Amar S More
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
| | - Jay S Mishra
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
| | - Gary D V Hankins
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
| | - Chandra Yallampalli
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas
| | - Kunju Sathishkumar
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
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Dominguez Rieg JA, Burt JM, Ruth P, Rieg T. P2Y₂ receptor activation decreases blood pressure via intermediate conductance potassium channels and connexin 37. Acta Physiol (Oxf) 2015; 213:628-41. [PMID: 25545736 PMCID: PMC4442688 DOI: 10.1111/apha.12446] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/14/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023]
Abstract
AIMS Nucleotides are important paracrine regulators of vascular tone. We previously demonstrated that activation of P2Y₂ receptors causes an acute, NO-independent decrease in blood pressure, indicating this signalling pathway requires an endothelial-derived hyperpolarization (EDH) response. To define the mechanisms by which activation of P2Y₂ receptors initiates EDH and vasodilation, we studied intermediate-conductance (KCa3.1, expressed in endothelial cells) and big-conductance potassium channels (KCa1.1, expressed in smooth muscle cells) as well as components of the myoendothelial gap junction, connexins 37 and 40 (Cx37, Cx40), all hypothesized to be part of the EDH response. METHODS We compared the effects of a P2Y₂/₄ receptor agonist in wild-type (WT) mice and in mice lacking KCa3.1, KCa1.1, Cx37 or Cx40 under anaesthesia, while monitoring intra-arterial blood pressure and heart rate. RESULTS Acute activation of P2Y₂/₄ receptors (0.01-3 mg kg(-1) body weight i.v.) caused a biphasic blood pressure response characterized by a dose-dependent and rapid decrease in blood pressure in WT (maximal response % of baseline at 3 mg kg(-1) : -38 ± 1%) followed by a consecutive increase in blood pressure (+44 ± 11%). The maximal responses in KCa3.1(-/-) and Cx37(-/-) were impaired (-13 ± 5, +17 ± 7 and -27 ± 1, +13 ± 3% respectively), whereas the maximal blood pressure decrease in response to acetylcholine at 3 μg kg(-1) was not significantly different (WT: -53 ± 3%; KCa3.1(-/-) : -52 ± 3; Cx37(-/-) : -53 ± 3%). KCa1.1(-/-) and Cx40(-/-) showed an identical biphasic response to P2Y2/4 receptor activation compared to WT. CONCLUSIONS The data suggest that the P2Y2/4 receptor activation elicits blood pressure responses via distinct mechanisms involving KCa3.1 and Cx37.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Connexins/deficiency
- Connexins/genetics
- Connexins/metabolism
- Dose-Response Relationship, Drug
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Heart Rate/drug effects
- Inosine/analogs & derivatives
- Inosine/pharmacology
- Intermediate-Conductance Calcium-Activated Potassium Channels/deficiency
- Intermediate-Conductance Calcium-Activated Potassium Channels/genetics
- Intermediate-Conductance Calcium-Activated Potassium Channels/metabolism
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/genetics
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/metabolism
- Male
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitric Oxide Synthase Type III/genetics
- Nitric Oxide Synthase Type III/metabolism
- Purinergic P2Y Receptor Agonists
- Receptors, Purinergic P2Y2/drug effects
- Receptors, Purinergic P2Y2/metabolism
- Signal Transduction/drug effects
- Uridine Triphosphate/analogs & derivatives
- Uridine Triphosphate/pharmacology
- Vasodilation/drug effects
- Gap Junction alpha-4 Protein
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Affiliation(s)
- J. A. Dominguez Rieg
- Department of Basic Sciences, Bastyr University California, San Diego, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
| | - J. M. Burt
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - P. Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Tübingen, Tübingen, Germany
| | - T. Rieg
- VA San Diego Healthcare System, San Diego, CA, USA
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA
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Oliván-Viguera A, Valero MS, Coleman N, Brown BM, Laría C, Murillo MD, Gálvez JA, Díaz-de-Villegas MD, Wulff H, Badorrey R, Köhler R. A novel pan-negative-gating modulator of KCa2/3 channels, fluoro-di-benzoate, RA-2, inhibits endothelium-derived hyperpolarization-type relaxation in coronary artery and produces bradycardia in vivo. Mol Pharmacol 2014; 87:338-48. [PMID: 25468883 DOI: 10.1124/mol.114.095745] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Small/intermediate conductance KCa channels (KCa2/3) are Ca(2+)/calmodulin regulated K(+) channels that produce membrane hyperpolarization and shape neurologic, epithelial, cardiovascular, and immunologic functions. Moreover, they emerged as therapeutic targets to treat cardiovascular disease, chronic inflammation, and some cancers. Here, we aimed to generate a new pharmacophore for negative-gating modulation of KCa2/3 channels. We synthesized a series of mono- and dibenzoates and identified three dibenzoates [1,3-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate) (RA-2), 1,2-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate), and 1,4-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate)] with inhibitory efficacy as determined by patch clamp. Among them, RA-2 was the most drug-like and inhibited human KCa3.1 with an IC50 of 17 nM and all three human KCa2 subtypes with similar potencies. RA-2 at 100 nM right-shifted the KCa3.1 concentration-response curve for Ca(2+) activation. The positive-gating modulator naphtho[1,2-d]thiazol-2-ylamine (SKA-31) reversed channel inhibition at nanomolar RA-2 concentrations. RA-2 had no considerable blocking effects on distantly related large-conductance KCa1.1, Kv1.2/1.3, Kv7.4, hERG, or inwardly rectifying K(+) channels. In isometric myography on porcine coronary arteries, RA-2 inhibited bradykinin-induced endothelium-derived hyperpolarization (EDH)-type relaxation in U46619-precontracted rings. Blood pressure telemetry in mice showed that intraperitoneal application of RA-2 (≤100 mg/kg) did not increase blood pressure or cause gross behavioral deficits. However, RA-2 decreased heart rate by ≈145 beats per minute, which was not seen in KCa3.1(-/-) mice. In conclusion, we identified the KCa2/3-negative-gating modulator, RA-2, as a new pharmacophore with nanomolar potency. RA-2 may be of use to generate structurally new types of negative-gating modulators that could help to define the physiologic and pathomechanistic roles of KCa2/3 in the vasculature, central nervous system, and during inflammation in vivo.
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Affiliation(s)
- Aida Oliván-Viguera
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Marta Sofía Valero
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Nicole Coleman
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Brandon M Brown
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Celia Laría
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - María Divina Murillo
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - José A Gálvez
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - María D Díaz-de-Villegas
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Heike Wulff
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Ramón Badorrey
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Ralf Köhler
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.).
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Chennupati R, Lamers WH, Koehler SE, De Mey JGR. Endothelium-dependent hyperpolarization-related relaxations diminish with age in murine saphenous arteries of both sexes. Br J Pharmacol 2014; 169:1486-99. [PMID: 23488619 DOI: 10.1111/bph.12175] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 02/08/2013] [Accepted: 02/17/2013] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE We investigated the effects of aging on the contributions of NO and endothelium-dependent hyperpolarization (EDH) to endothelium-dependent relaxation in saphenous arteries of male and female C57BL/6J mice aged 12, 34 and 64 weeks. EXPERIMENTAL APPROACH Vasomotor responses of saphenous arteries were analysed by wire myography in the absence and presence of stimuli of the endothelium, inhibitors of NOS, and inhibitors and stimulants of small (KCa 2.3) and intermediate (KCa 3.1) conductance calcium-activated potassium channels. KEY RESULTS Arterial relaxing responses to sodium nitroprusside and to ACh in the absence of pharmacological inhibitors (indomethacin and L-NAME), were similar in all age groups and sexes, but those mediated by endothelium-derived NO were slightly but significantly increased in 64-week-old male mice. In the presence of inhibitors, 12-week-old animals showed pronounced ACh-induced relaxation, which was significantly reduced in 34- and 64-week-old mice of both sexes. The EDH-related component of ACh-induced relaxations was abolished by TRAM-34 (KCa 3.1 blocker) or UCL 1684 (KCa 2.3 blocker). Although the maximal relaxation induced by NS309 (KCa activator) was not affected by aging, the sensitivity for NS309 significantly decreased with aging. The presence of SKA-31 (KCa modulator) potentiated relaxations induced by ACh in arteries of 12-week-old but not older mice. CONCLUSION AND IMPLICATIONS In a small muscular artery of mice of either sex, total endothelium-dependent relaxation is not affected by age. However, possibly due to changes in KCa channel function, the contribution of EDH to endothelium-dependent relaxations decreased with age. The contribution of endothelium-derived NO increases in old male mice.
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Affiliation(s)
- Ramesh Chennupati
- Department of Anatomy and Embryology, Maastricht University, Maastricht, The Netherlands
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Garneau L, Klein H, Lavoie MF, Brochiero E, Parent L, Sauvé R. Aromatic-aromatic interactions between residues in KCa3.1 pore helix and S5 transmembrane segment control the channel gating process. ACTA ACUST UNITED AC 2014; 143:289-307. [PMID: 24470490 PMCID: PMC4001770 DOI: 10.1085/jgp.201311097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Interactions between aromatic amino acid residues in the pore helix and S5 transmembrane domain control gating of the Ca2+-activated potassium channel KCa3.1. The Ca2+-activated potassium channel KCa3.1 is emerging as a therapeutic target for a large variety of health disorders. One distinguishing feature of KCa3.1 is that the channel open probability at saturating Ca2+ concentrations (Pomax) is low, typically 0.1–0.2 for KCa3.1 wild type. This observation argues for the binding of Ca2+ to the calmodulin (CaM)–KCa3.1 complex, promoting the formation of a preopen closed-state configuration leading to channel opening. We have previously shown that the KCa3.1 active gate is most likely located at the level of the selectivity filter. As Ca2+-dependent gating of KCa3.1 originates from the binding of Ca2+ to CaM in the C terminus, the hypothesis of a gate located at the level of the selectivity filter requires that the conformational change initiated in the C terminus be transmitted to the S5 and S6 transmembrane helices, with a resulting effect on the channel pore helix directly connected to the selectivity filter. A study was thus undertaken to determine to what extent the interactions between the channel pore helix with the S5 and S6 transmembrane segments contribute to KCa3.1 gating. Molecular dynamics simulations first revealed that the largest contact area between the pore helix and the S5 plus S6 transmembrane helices involves residue F248 at the C-terminal end of the pore helix. Unitary current recordings next confirmed that modulating aromatic–aromatic interactions between F248 and W216 of the S5 transmembrane helical segment and/or perturbing the interactions between F248 and residues in S6 surrounding the glycine hinge G274 cause important changes in Pomax. This work thus provides the first evidence for a key contribution of the pore helix in setting Pomax by stabilizing the channel closed configuration through aromatic–aromatic interactions involving F248 of the pore helix. We propose that the interface pore helix/S5 constitutes a promising site for designing KCa3.1 potentiators.
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Affiliation(s)
- Line Garneau
- Department of Physiology and Membrane Protein Research Group, 2 Centre de recherche du Centre hospitalier de l'Université de Montréal, and 3 Department of Medicine, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
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Albarwani S, Al-Siyabi S, Al-Husseini I, Al-Ismail A, Al-Lawati I, Al-Bahrani I, Tanira MO. Lisinopril alters contribution of nitric oxide and K(Ca) channels to vasodilatation in small mesenteric arteries of spontaneously hypertensive rats. Physiol Res 2014; 64:39-49. [PMID: 25194131 DOI: 10.33549/physiolres.932780] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
To investigate lisinopril effect on the contribution of nitric oxide (NO) and K(Ca) channels to acetylcholine (ACh)-induced relaxation in isolated mesenteric arteries of spontaneously hypertensive rats (SHRs). Third branch mesenteric arteries isolated from lisinopril treated SHR rats (20 mg/kg/day for ten weeks, SHR-T) or untreated (SHR-UT) or normotensive WKY rats were mounted on tension myograph and ACh concentration-response curves were obtained. Westernblotting of eNOS and K(Ca) channels was performed. ACh-induced relaxations were similar in all groups while L-NMMA and indomethacin caused significant rightward shift only in SHR-T group. Apamin and TRAM-34 (SK(Ca) and IK(Ca) channels blockers, respectively) significantly attenuated ACh-induced maximal relaxation by similar magnitude in vessels from all three groups. In the presence of L-NMMA, indomethacin, apamin and TRAM-34 further attenuated ACh-induced relaxation only in SHR-T. Furthermore, lisinopril treatment increased expression of eNOS, SK(Ca) and BK(Ca) proteins. Lisinopril treatment increased expression of eNOS, SK(Ca), BK(Ca) channel proteins and increased the contribution of NO to ACh-mediated relaxation. This increased role of NO was apparent only when EDHF component was blocked by inhibiting SK(Ca) and IK(Ca) channels. Such may suggest that in mesenteric arteries, non-EDHF component functions act as a reserve system to provide compensatory vasodilatation if (and when) hyperpolarization that is mediated by SK(Ca) and IK(Ca) channels is reduced.
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Affiliation(s)
- S Albarwani
- Sultan Qaboos University, College of Medicine and Health Sciences, Muscat, Oman.
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Coleman N, Brown BM, Oliván-Viguera A, Singh V, Olmstead MM, Valero MS, Köhler R, Wulff H. New positive Ca2+-activated K+ channel gating modulators with selectivity for KCa3.1. Mol Pharmacol 2014; 86:342-57. [PMID: 24958817 DOI: 10.1124/mol.114.093286] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Small-conductance (KCa2) and intermediate-conductance (KCa3.1) calcium-activated K(+) channels are voltage-independent and share a common calcium/calmodulin-mediated gating mechanism. Existing positive gating modulators like EBIO, NS309, or SKA-31 activate both KCa2 and KCa3.1 channels with similar potency or, as in the case of CyPPA and NS13001, selectively activate KCa2.2 and KCa2.3 channels. We performed a structure-activity relationship (SAR) study with the aim of optimizing the benzothiazole pharmacophore of SKA-31 toward KCa3.1 selectivity. We identified SKA-111 (5-methylnaphtho[1,2-d]thiazol-2-amine), which displays 123-fold selectivity for KCa3.1 (EC50 111 ± 27 nM) over KCa2.3 (EC50 13.7 ± 6.9 μM), and SKA-121 (5-methylnaphtho[2,1-d]oxazol-2-amine), which displays 41-fold selectivity for KCa3.1 (EC50 109 nM ± 14 nM) over KCa2.3 (EC50 4.4 ± 1.6 μM). Both compounds are 200- to 400-fold selective over representative KV (KV1.3, KV2.1, KV3.1, and KV11.1), NaV (NaV1.2, NaV1.4, NaV1.5, and NaV1.7), as well as CaV1.2 channels. SKA-121 is a typical positive-gating modulator and shifts the calcium-concentration response curve of KCa3.1 to the left. In blood pressure telemetry experiments, SKA-121 (100 mg/kg i.p.) significantly lowered mean arterial blood pressure in normotensive and hypertensive wild-type but not in KCa3.1(-/-) mice. SKA-111, which was found in pharmacokinetic experiments to have a much longer half-life and to be much more brain penetrant than SKA-121, not only lowered blood pressure but also drastically reduced heart rate, presumably through cardiac and neuronal KCa2 activation when dosed at 100 mg/kg. In conclusion, with SKA-121, we generated a KCa3.1-specific positive gating modulator suitable for further exploring the therapeutical potential of KCa3.1 activation.
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Affiliation(s)
- Nichole Coleman
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Brandon M Brown
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Aida Oliván-Viguera
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Vikrant Singh
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Marilyn M Olmstead
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Marta Sofia Valero
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Ralf Köhler
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Heike Wulff
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
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Waeckel L, Bertin F, Clavreul N, Damery T, Köhler R, Paysant J, Sansilvestri-Morel P, Simonet S, Vayssettes-Courchay C, Wulff H, Verbeuren TJ, Félétou M. Preserved regulation of renal perfusion pressure by small and intermediate conductance KCa channels in hypertensive mice with or without renal failure. Pflugers Arch 2014; 467:817-31. [DOI: 10.1007/s00424-014-1542-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/19/2014] [Accepted: 05/19/2014] [Indexed: 11/29/2022]
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Wandall-Frostholm C, Skaarup LM, Sadda V, Nielsen G, Hedegaard ER, Mogensen S, Köhler R, Simonsen U. Pulmonary hypertension in wild type mice and animals with genetic deficit in KCa2.3 and KCa3.1 channels. PLoS One 2014; 9:e97687. [PMID: 24858807 PMCID: PMC4032241 DOI: 10.1371/journal.pone.0097687] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 04/22/2014] [Indexed: 11/18/2022] Open
Abstract
Objective In vascular biology, endothelial KCa2.3 and KCa3.1 channels contribute to arterial blood pressure regulation by producing membrane hyperpolarization and smooth muscle relaxation. The role of KCa2.3 and KCa3.1 channels in the pulmonary circulation is not fully established. Using mice with genetically encoded deficit of KCa2.3 and KCa3.1 channels, this study investigated the effect of loss of the channels in hypoxia-induced pulmonary hypertension. Approach and Result Male wild type and KCa3.1−/−/KCa2.3T/T(+DOX) mice were exposed to chronic hypoxia for four weeks to induce pulmonary hypertension. The degree of pulmonary hypertension was evaluated by right ventricular pressure and assessment of right ventricular hypertrophy. Segments of pulmonary arteries were mounted in a wire myograph for functional studies and morphometric studies were performed on lung sections. Chronic hypoxia induced pulmonary hypertension, right ventricular hypertrophy, increased lung weight, and increased hematocrit levels in either genotype. The KCa3.1−/−/KCa2.3T/T(+DOX) mice developed structural alterations in the heart with increased right ventricular wall thickness as well as in pulmonary vessels with increased lumen size in partially- and fully-muscularized vessels and decreased wall area, not seen in wild type mice. Exposure to chronic hypoxia up-regulated the gene expression of the KCa2.3 channel by twofold in wild type mice and increased by 2.5-fold the relaxation evoked by the KCa2.3 and KCa3.1 channel activator NS309, whereas the acetylcholine-induced relaxation - sensitive to the combination of KCa2.3 and KCa3.1 channel blockers, apamin and charybdotoxin - was reduced by 2.5-fold in chronic hypoxic mice of either genotype. Conclusion Despite the deficits of the KCa2.3 and KCa3.1 channels failed to change hypoxia-induced pulmonary hypertension, the up-regulation of KCa2.3-gene expression and increased NS309-induced relaxation in wild-type mice point to a novel mechanism to counteract pulmonary hypertension and to a potential therapeutic utility of KCa2.3/KCa3.1 activators for the treatment of pulmonary hypertension.
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Affiliation(s)
| | | | - Veeranjaneyulu Sadda
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Institute for Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | - Gorm Nielsen
- Institute for Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | | | - Susie Mogensen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Ralf Köhler
- Institute for Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
- Aragon Institute of Health Sciences I+CS and ARAID, Zaragoza, Spain
| | - Ulf Simonsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
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Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
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Windler R, de Wit C. Perspectives: The Ca2+-dependent K+-channel KCa3.1 as a therapeutic target in cardiovascular disease. Eur Heart J Suppl 2014. [DOI: 10.1093/eurheartj/sut008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Jenkins DP, Yu W, Brown BM, Løjkner LD, Wulff H. Development of a QPatch automated electrophysiology assay for identifying KCa3.1 inhibitors and activators. Assay Drug Dev Technol 2013; 11:551-60. [PMID: 24351043 PMCID: PMC3870577 DOI: 10.1089/adt.2013.543] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The intermediate-conductance Ca(2+)-activated K(+) channel KCa3.1 (also known as KCNN4, IK1, or the Gárdos channel) plays an important role in the activation of T and B cells, mast cells, macrophages, and microglia by regulating membrane potential, cellular volume, and calcium signaling. KCa3.1 is further involved in the proliferation of dedifferentiated vascular smooth muscle cells and fibroblast and endothelium-derived hyperpolarization responses in the vascular endothelium. Accordingly, KCa3.1 inhibitors are therapeutically interesting as immunosuppressants and for the treatment of a wide range of fibroproliferative disorders, whereas KCa3.1 activators constitute a potential new class of endothelial function preserving antihypertensives. Here, we report the development of QPatch assays for both KCa3.1 inhibitors and activators. During assay optimization, the Ca(2+) sensitivity of KCa3.1 was studied using varying intracellular Ca(2+) concentrations. A free Ca(2+) concentration of 1 μM was chosen to optimally test inhibitors. To identify activators, which generally act as positive gating modulators, a lower Ca(2+) concentration (∼200 nM) was used. The QPatch results were benchmarked against manual patch-clamp electrophysiology by determining the potency of several commonly used KCa3.1 inhibitors (TRAM-34, NS6180, ChTX) and activators (EBIO, riluzole, SKA-31). Collectively, our results demonstrate that the QPatch provides a comparable but much faster approach to study compound interactions with KCa3.1 channels in a robust and reliable assay.
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Affiliation(s)
| | - Weifeng Yu
- Sophion Bioscience, Inc., North Brunswick, New Jersey
| | - Brandon M. Brown
- Department of Pharmacology, University of California, Davis, California
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California
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Radtke J, Schmidt K, Wulff H, Köhler R, de Wit C. Activation of KCa3.1 by SKA-31 induces arteriolar dilatation and lowers blood pressure in normo- and hypertensive connexin40-deficient mice. Br J Pharmacol 2013; 170:293-303. [PMID: 23734697 PMCID: PMC3834754 DOI: 10.1111/bph.12267] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 05/06/2013] [Accepted: 05/22/2013] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The calcium-activated potassium channel KCa3.1 is expressed in the vascular endothelium where its activation causes endothelial hyperpolarization and initiates endothelium-derived hyperpolarization (EDH)-dependent dilatation. Here, we investigated whether pharmacological activation of KCa3.1 dilates skeletal muscle arterioles and whether myoendothelial gap junctions formed by connexin40 (Cx40) are required for EDH-type dilatations and pressure depressor responses in vivo. EXPERIMENTAL APPROACH We performed intravital microscopy in the cremaster muscle microcirculation and blood pressure telemetry in Cx40-deficient mice. KEY RESULTS In wild-type mice, the KCa3.1-activator SKA-31 induced pronounced concentration-dependent arteriolar EDH-type dilatations, amounting to ∼40% of maximal dilatation, and enhanced the effects of ACh. These responses were absent in mice devoid of KCa3.1 channels. In contrast, SKA-31-induced dilatations were not attenuated in mice with endothelial cells deficient in Cx40 (Cx40(fl/fl):Tie2-Cre). In isolated endothelial cell clusters, SKA-31 induced hyperpolarizations of similar magnitudes (by ∼38 mV) in Cx40(fl/fl):Tie2-Cre, ubiquitous Cx40-deficient mice (Cx40(-/-)) and controls (Cx40(fl/fl)), which were reversed by the specific KCa3.1-blocker TRAM-34. In normotensive wild-type and Cx40(fl/fl):Tie2-Cre as well as in hypertensive Cx40(-/-) animals, i.p. injections of SKA-31 (30 and 100 mg·kg(-1)) decreased arterial pressure by ∼32 mmHg in all genotypes. The depressor response to 100 mg·kg(-1) SKA-31 was associated with a decrease in heart rate. CONCLUSIONS AND IMPLICATIONS We conclude that endothelial hyperpolarization evoked by pharmacological activation of KCa3.1 channels induces EDH-type arteriolar dilatations that are independent of endothelial Cx40 and Cx40-containing myoendothelial gap junctions. As SKA-31 reduced blood pressure in hypertensive Cx40-deficient mice, KCa3.1 activators may be useful drugs for severe treatment-resistant hypertension.
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Affiliation(s)
- Josephine Radtke
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Lübeck, Germany
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Endothelial small-conductance and intermediate-conductance KCa channels: an update on their pharmacology and usefulness as cardiovascular targets. J Cardiovasc Pharmacol 2013; 61:102-12. [PMID: 23107876 DOI: 10.1097/fjc.0b013e318279ba20] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Most cardiovascular researchers are familiar with intermediate-conductance KCa3.1 and small-conductance KCa2.3 channels because of their contribution to endothelium-derived hyperpolarization. However, to immunologists and neuroscientists, these channels are primarily known for their role in lymphocyte activation and neuronal excitability. KCa3.1 is involved in the proliferation and migration of T cells, B cells, mast cells, macrophages, fibroblasts, and dedifferentiated vascular smooth muscle cells and is, therefore, being pursued as a potential target for use in asthma, immunosuppression, and fibroproliferative disorders. In contrast, the 3 KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) contribute to the neuronal medium afterhyperpolarization and, depending on the type of neuron, are involved in determining firing rates and frequencies or in regulating bursting. KCa2 activators are accordingly being studied as potential therapeutics for ataxia and epilepsy, whereas KCa2 channel inhibitors like apamin have long been known to improve learning and memory in rodents. Given this background, we review the recent discoveries of novel KCa3.1 and KCa2.3 modulators and critically assess the potential of KCa activators for the treatment of diabetes and cardiovascular diseases by improving endothelium-derived hyperpolarizations.
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Takai J, Santu A, Zheng H, Koh SD, Ohta M, Filimban LM, Lemaître V, Teraoka R, Jo H, Miura H. Laminar shear stress upregulates endothelial Ca²⁺-activated K⁺ channels KCa2.3 and KCa3.1 via a Ca²⁺/calmodulin-dependent protein kinase kinase/Akt/p300 cascade. Am J Physiol Heart Circ Physiol 2013; 305:H484-93. [PMID: 23792675 DOI: 10.1152/ajpheart.00642.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In endothelial cells (ECs), Ca²⁺-activated K⁺ channels KCa2.3 and KCa3.1 play a crucial role in the regulation of arterial tone via producing NO and endothelium-derived hyperpolarizing factors. Since a rise in intracellular Ca²⁺ levels and activation of p300 histone acetyltransferase are early EC responses to laminar shear stress (LS) for the transcriptional activation of genes, we examined the role of Ca²⁺/calmodulin-dependent kinase kinase (CaMKK), the most upstream element of a Ca²⁺/calmodulin-kinase cascade, and p300 in LS-dependent regulation of KCa2.3 and KCa3.1 in ECs. Exposure to LS (15 dyn/cm²) for 24 h markedly increased KCa2.3 and KCa3.1 mRNA expression in cultured human coronary artery ECs (3.2 ± 0.4 and 45 ± 10 fold increase, respectively; P < 0.05 vs. static condition; n = 8-30), whereas oscillatory shear (OS; ± 5 dyn/cm² × 1 Hz) moderately increased KCa3.1 but did not affect KCa2.3. Expression of KCa2.1 and KCa2.2 was suppressed under both LS and OS conditions, whereas KCa1.1 was slightly elevated in LS and unchanged in OS. Inhibition of CaMKK attenuated LS-induced increases in the expression and channel activity of KCa2.3 and KCa3.1, and in phosphorylation of Akt (Ser473) and p300 (Ser1834). Inhibition of Akt abolished the upregulation of these channels by diminishing p300 phosphorylation. Consistently, disruption of the interaction of p300 with transcription factors eliminated the induction of these channels. Thus a CaMKK/Akt/p300 cascade plays an important role in LS-dependent induction of KCa2.3 and KCa3.1 expression, thereby regulating EC function and adaptation to hemodynamic changes.
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Affiliation(s)
- Jun Takai
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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49
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Simonet S, Isabelle M, Bousquenaud M, Clavreul N, Félétou M, Vayssettes-Courchay C, Verbeuren TJ. KCa 3.1 channels maintain endothelium-dependent vasodilatation in isolated perfused kidneys of spontaneously hypertensive rats after chronic inhibition of NOS. Br J Pharmacol 2013; 167:854-67. [PMID: 22646737 DOI: 10.1111/j.1476-5381.2012.02062.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The purpose of the study was to investigate renal endothelium-dependent vasodilatation in a model of severe hypertension associated with kidney injury. EXPERIMENTAL APPROACH Changes in perfusion pressure were measured in isolated, perfused kidneys taken from 18-week-old Wistar-Kyoto rat (WKY), spontaneously hypertensive rats (SHR) and SHR treated for 2 weeks with N(ω) -nitro-L-arginine methyl ester in the drinking water (L-NAME-treated SHR, 6 mg·kg(-1) ·day(-1) ). KEY RESULTS Acetylcholine caused similar dose-dependent renal dilatation in the three groups. In vitro administration of indomethacin did not alter the vasodilatation, while the addition of N(w) -nitro-L-arginine (L-NA) produced a differential inhibition of the vasodilatation, (inhibition in WKY > SHR > L-NAME-treated SHR). Further addition of ODQ, an inhibitor of soluble guanylyl cyclase, abolished the responses to sodium nitroprusside but did not affect the vasodilatation to acetylcholine. However, the addition of TRAM-34 (or charybdotoxin) inhibitors of Ca(2+) -activated K(+) channels of intermediate conductance (K(Ca) 3.1), blocked the vasodilatation to acetylcholine, while apamin, an inhibitor of Ca(2+) -activated K(+) channels of small conductance (K(Ca) 2.3), was ineffective. Dilatation induced by an opener of K(Ca) 3.1/K(Ca) 2.3 channels, NS-309, was also blocked by TRAM-34, but not by apamin. The magnitude and duration of NS-309-induced vasodilatation and the renal expression of mRNA for K(Ca) 3.1, but not K(Ca) 2.3, channels followed the same ranking order (WKY < SHR < L-NAME-treated SHR). CONCLUSIONS AND IMPLICATIONS In SHR kidneys, an EDHF-mediated response, involving activation of K(Ca) 3.1 channels, contributed to the mechanism of endothelium-dependent vasodilatation. In kidneys from L-NAME-treated SHR, up-regulation of this pathway fully compensated for the decrease in NO availability.
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Mishra RC, Belke D, Wulff H, Braun AP. SKA-31, a novel activator of SK(Ca) and IK(Ca) channels, increases coronary flow in male and female rat hearts. Cardiovasc Res 2012; 97:339-48. [PMID: 23118129 DOI: 10.1093/cvr/cvs326] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AIMS Endothelial SK(Ca) and IK(Ca) channels play an important role in the regulation of vascular function and systemic blood pressure. Based on our previous findings that small molecule activators of SK(Ca) and IK(Ca) channels (i.e. NS309 and SKA-31) can inhibit myogenic tone in isolated resistance arteries, we hypothesized that this class of compounds may induce effective vasodilation in an intact vascular bed, such as the coronary circulation. METHODS AND RESULTS In a Langendorff-perfused, beating rat heart preparation, acute bolus administrations of SKA-31 (0.01-5 µg) dose-dependently increased total coronary flow (25-30%) in both male and female hearts; these responses were associated with modest, secondary increases in left ventricular (LV) systolic pressure and heart rate. SKA-31 evoked responses in coronary flow, LV pressure, and heart rate were qualitatively comparable to acute responses evoked by bradykinin (1 µg) and adenosine (10 µg). In the presence of apamin and TRAM-34, selective blockers of SK(Ca) and IK(Ca) channels, respectively, SKA-31 and bradykinin-induced responses were largely inhibited, whereas the adenosine-induced changes were blocked by ∼40%; TRAM-34 alone produced less inhibition. Sodium nitroprusside (SNP, 0.2 μg bolus dose) evoked changes in coronary flow, LV pressure, and heart rate were similar to those induced by SKA-31, but were unaffected by apamin + TRAM-34. The NOS inhibitor L-NNA reduced bradykinin- and adenosine-evoked changes, but did not affect responses to either SKA-31 or SNP. CONCLUSION Our study demonstrates that SKA-31 can rapidly and reversibly induce dilation of the coronary circulation in intact functioning hearts under basal flow and contractility conditions.
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Affiliation(s)
- Ramesh C Mishra
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, Canada T2N 4N1
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