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Shvetsova AA, Gaynullina DK, Tarasova OS, Schubert R. Remodeling of Arterial Tone Regulation in Postnatal Development: Focus on Smooth Muscle Cell Potassium Channels. Int J Mol Sci 2021; 22:ijms22115413. [PMID: 34063769 PMCID: PMC8196626 DOI: 10.3390/ijms22115413] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/15/2021] [Accepted: 05/18/2021] [Indexed: 11/30/2022] Open
Abstract
Maturation of the cardiovascular system is associated with crucial structural and functional remodeling. Thickening of the arterial wall, maturation of the sympathetic innervation, and switching of the mechanisms of arterial contraction from calcium-independent to calcium-dependent occur during postnatal development. All these processes promote an almost doubling of blood pressure from the moment of birth to reaching adulthood. This review focuses on the developmental alterations of potassium channels functioning as key smooth muscle membrane potential determinants and, consequently, vascular tone regulators. We present evidence that the pattern of potassium channel contribution to vascular control changes from Kir2, Kv1, Kv7 and TASK-1 channels to BKCa channels with maturation. The differences in the contribution of potassium channels to vasomotor tone at different stages of postnatal life should be considered in treatment strategies of cardiovascular diseases associated with potassium channel malfunction.
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Affiliation(s)
- Anastasia A. Shvetsova
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; (D.K.G.); (O.S.T.)
- Correspondence:
| | - Dina K. Gaynullina
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; (D.K.G.); (O.S.T.)
- Department of Physiology, Russian National Research Medical University, 117997 Moscow, Russia
| | - Olga S. Tarasova
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; (D.K.G.); (O.S.T.)
- Laboratory of Exercise Physiology, State Research Center of the Russian Federation-Institute for Biomedical Problems, Russian Academy of Sciences, 123007 Moscow, Russia
| | - Rudolf Schubert
- Physiology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, 86159 Augsburg, Germany;
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Bisen S, Simakova MN, Dopico AM, Bukiya AN. Large conductance voltage- and calcium-gated potassium channels (BK) in cerebral artery myocytes of perinatal fetal primates share several major characteristics with the adult phenotype. PLoS One 2018; 13:e0203199. [PMID: 30212531 PMCID: PMC6136719 DOI: 10.1371/journal.pone.0203199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 06/19/2018] [Indexed: 12/30/2022] Open
Abstract
Large conductance voltage- and calcium-gated channels (BK) control fundamental processes, including smooth muscle contractility and artery diameter. We used a baboon (Papio spp) model of pregnancy that is similar to that of humans to characterize BK channels in the middle cerebral artery and its branches in near-term (165 dGa) primate fetuses and corresponding pregnant mothers. In cell-attached patches (K+pipette = 135 mM) on freshly isolated fetal cerebral artery myocytes, BK currents were identified by large conductance, and voltage- and paxilline-sensitive effects. Their calcium sensitivity was confirmed by a lower Vhalf (transmembrane voltage needed to reach half-maximal current) in inside-out patches at 30 versus 3 μM [Ca2+]free. Immunostaining against the BK channel-forming alpha subunit revealed qualitatively similar levels of BK alpha protein-corresponding fluorescence in fetal and maternal myocytes. Fetal and maternal BK currents recorded at 3 μM [Ca2+]free from excised membrane patches had similar unitary current amplitude, and Vhalf. However, subtle differences between fetal and maternal BK channel phenotypes were detected in macroscopic current activation kinetics. To assess BK function at the organ level, fetal and maternal artery branches were pressurized in vitro at 30 mmHg and probed with the selective BK channel blocker paxilline (1 μM). The degree of paxilline-induced constriction was similar in fetal and maternal arteries, yet the constriction of maternal arteries was achieved sooner. In conclusion, we present a first identification and characterization of fetal cerebral artery BK channels in myocytes from primates. Although differences in BK channels between fetal and maternal arteries exist, the similarities reported herein advance the idea that vascular myocyte BK channels are functional near-term, and thus may serve as pharmacological targets during the perinatal-neonatal period.
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Affiliation(s)
- Shivantika Bisen
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Maria N. Simakova
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Alex M. Dopico
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Anna N. Bukiya
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
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Pearce WJ. The fetal cerebral circulation: three decades of exploration by the LLU Center for Perinatal Biology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 814:177-91. [PMID: 25015811 DOI: 10.1007/978-1-4939-1031-1_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
For more than three decades, research programs in the Center of Perinatal Biology have focused on the vascular biology of the fetal cerebral circulation. In the 1980s, research in the Center demonstrated that cerebral autoregulation operated over a narrower pressure range, and was more vulnerable to insults, in fetuses than in adults. Other studies were among the first to establish that compared to adult cerebral arteries, fetal cerebral arteries were more hydrated, contained smaller smooth muscle cells and less connective tissue, and had endothelium less capable of producing NO. Work in the 1990s revealed that pregnancy depressed reactivity to NO in extra-cerebral arteries, but elevated it in cerebral arteries through effects involving changes in cGMP metabolism. Comparative studies verified that fetal lamb cerebral arteries were an excellent model for cerebral arteries from human infants. Biochemical studies demonstrated that cGMP metabolism was dramatically upregulated, but that contraction was far more dependent on calcium influx, in fetal compared to adult cerebral arteries. Further studies established that chronic hypoxia accelerates functional maturation of fetal cerebral arteries, as indicated by increased contractile responses to adrenergic agonists and perivascular adrenergic nerves. In the 2000s, studies of signal transduction established age-dependent roles for PKG, PKC, PKA, ERK, ODC, IP3, myofilament calcium sensitivity, and many other mechanisms. These diverse studies clearly demonstrated that fetal cerebral arteries were functionally quite distinct compared to adult cerebral arteries. In the current decade, research in the Center has expanded to a more molecular focus on epigenetic mechanisms and their role in fetal vascular adaptation to chronic hypoxia, maternal drug abuse, and nutrient deprivation. Overall, the past three decades have transformed thinking about, and understanding of, the fetal cerebral circulation due in no small part to the sustained research efforts by faculty and staff in the Center for Perinatal Biology.
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Affiliation(s)
- William J Pearce
- Center for Perinatal Biology, Loma Linda University School of Medicine, 92350, Loma Linda, CA, USA,
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Goyal R, Goyal D, Chu N, Van Wickle J, Longo LD. Cerebral artery alpha-1 AR subtypes: high altitude long-term acclimatization responses. PLoS One 2014; 9:e112784. [PMID: 25393740 PMCID: PMC4231100 DOI: 10.1371/journal.pone.0112784] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 10/14/2014] [Indexed: 11/19/2022] Open
Abstract
In response to hypoxia and other stress, the sympathetic (adrenergic) nervous system regulates arterial contractility and blood flow, partly through differential activities of the alpha1 (α1) - adrenergic receptor (AR) subtypes (α1A-, α1B-, and α1D-AR). Thus, we tested the hypothesis that with acclimatization to long-term hypoxia (LTH), contractility of middle cerebral arteries (MCA) is regulated by changes in expression and activation of the specific α1-AR subtypes. We conducted experiments in MCA from adult normoxic sheep maintained near sea level (300 m) and those exposed to LTH (110 days at 3801 m). Following acclimatization to LTH, ovine MCA showed a 20% reduction (n = 5; P<0.05) in the maximum tension achieved by 10-5 M phenylephrine (PHE). LTH-acclimatized cerebral arteries also demonstrated a statistically significant (P<0.05) inhibition of PHE-induced contractility in the presence of specific α1-AR subtype antagonists. Importantly, compared to normoxic vessels, there was significantly greater (P<0.05) α1B-AR subtype mRNA and protein levels in LTH acclimatized MCA. Also, our results demonstrate that extracellular regulated kinase 1 and 2 (ERK1/2)-mediated negative feedback regulation of PHE-induced contractility is modulated by α1B-AR subtype. Overall, in ovine MCA, LTH produces profound effects on α1-AR subtype expression and function.
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Affiliation(s)
- Ravi Goyal
- Center for Perinatal Biology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
- Epigenuity LLC, Loma Linda, California, United States of America
| | - Dipali Goyal
- Center for Perinatal Biology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
- Epigenuity LLC, Loma Linda, California, United States of America
| | - Nina Chu
- Center for Perinatal Biology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
- Epigenuity LLC, Loma Linda, California, United States of America
| | - Jonathan Van Wickle
- Center for Perinatal Biology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
- Epigenuity LLC, Loma Linda, California, United States of America
| | - Lawrence D. Longo
- Center for Perinatal Biology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California, United States of America
- Epigenuity LLC, Loma Linda, California, United States of America
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Hu XQ, Zhang L. Function and regulation of large conductance Ca(2+)-activated K+ channel in vascular smooth muscle cells. Drug Discov Today 2012; 17:974-87. [PMID: 22521666 PMCID: PMC3414640 DOI: 10.1016/j.drudis.2012.04.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/06/2012] [Accepted: 04/05/2012] [Indexed: 12/23/2022]
Abstract
Large conductance Ca(2+)-activated K(+) (BK(Ca)) channels are abundantly expressed in vascular smooth muscle cells. Activation of BK(Ca) channels leads to hyperpolarization of cell membrane, which in turn counteracts vasoconstriction. Therefore, BK(Ca) channels have an important role in regulation of vascular tone and blood pressure. The activity of BK(Ca) channels is subject to modulation by various factors. Furthermore, the function of BK(Ca) channels are altered in both physiological and pathophysiological conditions, such as pregnancy, hypertension and diabetes, which has dramatic impacts on vascular tone and hemodynamics. Consequently, compounds and genetic manipulation that alter activity and expression of the channel might be of therapeutic interest.
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Affiliation(s)
- Xiang-Qun Hu
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
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Abstract
Endothelial dysfunction can develop at an early age in children with risk factors for cardiovascular disease. A clear understanding of the nature of this dysfunction and how it can worsen over time requires detailed information on the normal growth-related changes in endothelial function on which the pathological changes are superimposed. This review summarizes our current understanding of these normal changes, as derived from studies in four different mammalian species. Although the endothelium plays an important role in controlling vascular tone from birth onward, the vasoactive molecules that mediate this control often change during postnatal or juvenile growth. The specifics of this transition to an adult endothelial cell phenotype can vary depending on the vascular bed. During growth, the contribution of nitric oxide to endothelium-dependent dilation generally increases in the lung, cerebral cortex, and skeletal muscle, but decreases in the intestine. Endothelial capacity for release of other vasoactive factors (e.g., cyclooxygenase products, hydrogen peroxide, carbon monoxide) can also increase or decrease during growth. Although these changes have been well documented, there is less information on their underlying cellular or molecular events. Further research is required to clarify these mechanisms, and to evaluate the functional significance of such shifts in endothelial phenotype.
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MESH Headings
- Animals
- Animals, Newborn
- Cardiovascular Diseases/etiology
- Cardiovascular Diseases/physiopathology
- Cerebrovascular Circulation/physiology
- Endothelium, Vascular/growth & development
- Endothelium, Vascular/physiology
- Enterocolitis, Necrotizing/etiology
- Enterocolitis, Necrotizing/physiopathology
- Humans
- Infant, Newborn
- Intestines/blood supply
- Models, Animal
- Muscle, Skeletal/blood supply
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide/physiology
- Persistent Fetal Circulation Syndrome/etiology
- Persistent Fetal Circulation Syndrome/physiopathology
- Pulmonary Circulation/physiology
- Rats
- Risk Factors
- Sheep
- Swine
- Vascular Resistance/physiology
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Affiliation(s)
- Matthew A Boegehold
- Department of Physiology and Pharmacology and Center for Cardiovascular and Respiratory Sciences, Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV 26505-9105, USA.
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Goyal R, Mittal A, Chu N, Zhang L, Longo LD. alpha(1)-Adrenergic receptor subtype function in fetal and adult cerebral arteries. Am J Physiol Heart Circ Physiol 2010; 298:H1797-806. [PMID: 20348219 PMCID: PMC2886655 DOI: 10.1152/ajpheart.00112.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 03/24/2010] [Indexed: 11/22/2022]
Abstract
In the developing fetus, cerebral artery (CA) contractility demonstrates significant functional differences from that of the adult. This may be a consequence of differential activities of alpha(1)-adrenergic receptor (alpha(1)-AR) subtypes. Thus we tested the hypothesis that maturational differences in adrenergic-mediated CA contractility are, in part, a consequence of differential expression and/or activities of alpha(1)-AR subtypes. In CA from fetal ( approximately 140 days) and nonpregnant adult sheep, we used wire myography and imaging, with simultaneous measurement of tension and intracellular Ca(2+) concentration ([Ca(2+)](i)), radioimmunoassay, and Western immunoblots to examine phenylephrine (Phe)-induced contractile responses. The alpha(1A)-AR antagonists (5-MU and WB-4101) completely inhibited Phe-induced contraction in adult but not fetal CA; however, [Ca(2+)](i) increase was reduced significantly in both age groups. The alpha(1D)-AR antagonist (BMY-7378) blocked both Phe-induced contractions and Ca(2+) responses to a significantly greater extent in adult compared with fetal CA. In both age groups, inhibition of alpha(1A)-AR and alpha(1B)-AR, but not alpha(1D)-AR, significantly reduced inositol 1,4,5-trisphosphate responses to Phe. Western immunoblots demonstrated that the alpha(1)-AR subtype expression was only approximately 20% in fetal CA compared with the adult. Moreover, in fetal CA, the alpha(1D)-AR was expressed significantly greater than the other two subtypes. Also, in fetal but not adult CA, Phe induced a significant increase in activated ERK1/2; this increase in phosphorylated ERK was blocked by alpha(1B)-AR (CEC) and alpha(1D)-AR (BMY-7378) inhibitors, but not by alpha(1A)-AR inhibitors (5-MU or WB-4101). In conclusion, in the fetal CA, alpha(1B)-AR and alpha(1D)-AR subtypes play a key role in contractile response as well as in ERK activation. We speculate that in fetal CA alpha(1B)-AR and alpha(1D)-AR subtypes may be a critical factor associated with cerebrovascular growth and function.
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Affiliation(s)
- Ravi Goyal
- Center for Perinatal Biology, Department of Physiology and Pharmacology, Loma Linda Univ., School of Medicine, Loma Linda, CA 92350, USA
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8
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Goyal R, Mittal A, Chu N, Shi L, Zhang L, Longo LD. Maturation and the role of PKC-mediated contractility in ovine cerebral arteries. Am J Physiol Heart Circ Physiol 2009; 297:H2242-52. [PMID: 19749163 DOI: 10.1152/ajpheart.00681.2009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca2+-independent pathways such as protein kinase C (PKC), extracellular-regulated kinases 1 and 2 (ERK1/2), and Rho kinase 1 and 2 (ROCK1/2) play important roles in modulating cerebral vascular tone. Because the roles of these kinases vary with maturational age, we tested the hypothesis that PKC differentially regulates the Ca2+-independent pathways and their effects on cerebral arterial contractility with development. We simultaneously examined the responses of arterial tension and intracellular Ca2+ concentration and used Western immunoblot analysis to measure ERK1/2, RhoA, 20 kDa regulatory myosin light chain (MLC20), PKC-potentiated inhibitory protein of 17 kDa (CPI-17), and caldesmon. Phorbol 12,13-dibutyrate (PDBu)-mediated PKC activation produced a robust contractile response, which was increased a further 20 to 30% by U-0126 (MEK inhibitor) in cerebral arteries of both age groups. Of interest, in the fetal cerebral arteries, PDBu leads to an increased phosphorylation of ERK2 compared with ERK1, whereas in adult arteries, we observed an increased phosphorylation of ERK1 compared with ERK2. Also, in the present study, RhoA/ROCK played a significant role in the PDBu-mediated contractility of fetal cerebral arteries, whereas in adult cerebral arteries, CPI-17 and caldesmon had a significantly greater role compared with the fetus. PDBu also led to an increased MLC20 phosphorylation, a response blunted by the inhibition of myosin light chain kinase only in the fetus. Overall, the present study demonstrates an important maturational shift from RhoA/ROCK-mediated to CPI-17/caldesmon-mediated PKC-induced contractile response in ovine cerebral arteries.
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Affiliation(s)
- Ravi Goyal
- Department of Physiology, Center for Perinatal Biology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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Seçkin H, Yigitkanli K, Besalti O, Kosemehmetoglu K, Ozturk E, Simsek S, Belen D, Bavbek M. Lamotrigine attenuates cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits. ACTA ACUST UNITED AC 2008; 70:344-51; discussion 351. [DOI: 10.1016/j.surneu.2007.07.052] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 07/09/2007] [Indexed: 10/22/2022]
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Kinobe RT, Vlahakis JZ, Soong JM, Szarek WA, Brien JF, Longo LD, Nakatsu K. Heme oxygenase activity in fetal and adult sheep is not altered by acclimatization to high altitude hypoxia. Can J Physiol Pharmacol 2006; 84:893-901. [PMID: 17111034 DOI: 10.1139/y06-034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypoxic stress has been reported to induce the expression of stress proteins such as heme oxygenase (HO), which catalyze the breakdown of heme to generate biliverdin, ferrous iron, and carbon monoxide. These degradation products play a role in the regulation of a variety of processes such as vascular tone, inflammation, and central nervous system function. In mammals, there are 2 catalytically functional HO isozymes, HO-1 (inducible) and HO-2 (constitutive). HO-1 expression is regulated by an array of nonphysiological and physiological stimuli including acute hypoxemia. As relatively little is known of the HO response to prolonged hypoxia in whole animals other than small laboratory rodents, the aim of this work was to examine the effect of long-term hypoxia on total HO activity in fetal and adult ovine tissue. Sheep were maintained at high altitude (3820 m), after which the following tissues were harvested from near-term fetal and non-pregnant ewes for in vitro measurement of HO activity: left ventricle, renal papilla, lung apex, pulmonary artery, carotid artery, mesenteric artery, placental cotyledon, spleen, and brain frontal cortex. There were no significant differences between HO activities in tissues from hypoxic fetal and adult sheep compared with their normoxic controls. Fetal heart HO activities were higher than those of adult tissue (p < 0.05), whereas adult spleen HO activity was significantly higher than that of fetal tissue (p < 0.05). In conclusion, these data indicate that long-term exposure to high altitude hypoxia does not have a persistent effect on HO activity in ovine tissues. Also, except for the spleen where there is a high expression of HO-1 under normal conditions, tissue HO activity is correlated with the expression of HO-2, the constitutive isozyme.
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Affiliation(s)
- Robert T Kinobe
- Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario K7L 3N6, Canada
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Lin MT, Hessinger DA, Pearce WJ, Longo LD. Modulation of BK channel calcium affinity by differential phosphorylation in developing ovine basilar artery myocytes. Am J Physiol Heart Circ Physiol 2006; 291:H732-40. [PMID: 16840736 DOI: 10.1152/ajpheart.01357.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Large-conductance Ca2+-sensitive K+ (BK) channel activity is greater in basilar artery smooth muscle cells (SMCs) of the fetus than the adult, and this increased activity is associated with a lower BK channel Ca2+ set point (Ca0). Associated PKG activity is three times greater in BK channels from fetal than adult myocytes, whereas associated PKA activity is three times greater in channels from adult than fetal myocytes. We hypothesized that the change in Ca0 during development results from different levels of channel phosphorylation. In inside-out membrane patch preparations of basilar artery SMCs from adult and fetal sheep, we measured BK channel activity in four states of phosphorylation: native, dephosphorylated, PKA phosphorylated, and PKG phosphorylated. BK channels from adult and fetus exhibited similar voltage-activation curves, Ca0 values, and Ca2+ dissociation constants (Kd) for the dephosphorylated, PKA phosphorylated, and PKG phosphorylated states. However, voltage-activation curves of native fetal BK channels shifted significantly to the left of those of the adult, with Ca0 and Kd values half those of the adult. For the two age groups at each of the phosphorylation states, Ca0 and Kd produced linear relations when plotted against voltage at half-maximal channel activation. We conclude that the Ca0 and Kd values of the BK channel can be modulated by differential channel phosphorylation. Lower Ca0 and Kd values in BK channels of fetal myocytes can be explained by a greater extent of channel phosphorylation of fetal than adult myocytes.
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Affiliation(s)
- Mike T Lin
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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12
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Zhao Y, Zhang L, Longo LD. PKC-induced ERK1/2 interactions and downstream effectors in ovine cerebral arteries. Am J Physiol Regul Integr Comp Physiol 2005; 289:R164-71. [PMID: 15956760 DOI: 10.1152/ajpregu.00847.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both protein kinase C (PKC) and extracellular signal-regulated kinases (ERK1/2) are involved in mediating vascular smooth muscle contraction. We tested the hypotheses that in addition to PKC activation of ERK1/2, by negative feedback ERKs modulate PKC-induced contraction, and that their interactions modulate both thick and thin myofilament pathways. In ovine middle cerebral arteries (MCA), we measured isometric tension and intracellular free calcium concentration ([Ca(2+)](i)) responses to PKC stimulation [phorbol 12,13-dibutyrate (PDBu), 3 x 10(-6) M] in the absence or presence of ERK1/2 inhibition (U-0126, 10(-5) M). After PDBu +/- ERK1/2 inhibition, we also examined by Western immunoblot the levels of total and phosphorylated ERK1/2, caldesmon(Ser789), myosin light chain(20) (MLC(20)), and CPI-17. PDBu induced significant increase in tension in the absence of increased [Ca(2+)](i). PDBu also increased phosphorylated ERK1/2 levels, a response blocked by U-0126. In turn, U-0126 augmented PDBu-induced contractions. PDBu also was associated with significant increases in phosphorylated caldesmon(Ser789) and MLC(20) levels, each of which peaked at 5 to 10 min. PDBu also increased phosphorylated CPI-17 levels, which peaked at 2 to 3 min. Rho kinase inhibition (Y-27632, 3 x 10(-7) M) did not alter PDBu-induced contraction. These results support the idea that PKC activation can increase CPI-17 phosphorylation to decrease myosin light chain phosphatase activity. In turn, this increases MLC(20) phosphorylation in the thick filament pathway and increases Ca(2+) sensitivity. In addition, ERK1/2-dependent phosphorylation of caldesmon(Ser789) was not necessary for PDBu-induced contraction and appears not to be involved in the reversal of caldesmon's inhibitory effect on actin-myosin ATPase.
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Affiliation(s)
- Yu Zhao
- Center for Perinatal Biology, Department of Physiology and Pharmacology, Loma Linda University, School of Medicine, Loma Linda, California 92350, USA
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13
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Longo LD, Pearce WJ. Fetal cerebrovascular acclimatization responses to high-altitude, long-term hypoxia: a model for prenatal programming of adult disease? Am J Physiol Regul Integr Comp Physiol 2005; 288:R16-24. [PMID: 15590993 DOI: 10.1152/ajpregu.00462.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the past several decades, many risk factors for cerebrovascular and cardiovascular disease have been identified. More recently, it has been appreciated that inadequate nutrition and/or other intrauterine factors during fetal development may play an important role in the genesis of these conditions. An additional stress factor that may "program" the fetus for disease later in life is chronic hypoxia. In studies originally designed to examine the function of developing cerebral arterial function in response to long-term hypoxia (LTH), it has become clear that many cellular and subcellular changes may have important implications for later life. Here we review some of the significant alterations in fetal cerebral artery structure and function induced by high-altitude (3,820 m, 12,470 ft) LTH ( approximately 110 days). LTH is associated with augmentation or upregulation of presynaptic functions, including responses to perivascular (i.e., sympathetic) nerve stimulation, and structural maturational changes. In contrast, many postsynaptic functions related to the Ca(2+)-dependent contractile pathway tend to be downregulated, whereas elements of the Ca(2+)-independent contraction pathway are upregulated. The results emphasize the role of high-altitude LTH in modulating many aspects of electromechanical and pharmacomechanical coupling in the developing cerebral vasculature. A complicating factor is that the regulation of cerebrovascular tone by Ca(2+)-dependent and Ca(2+)-independent pathways changes significantly as a function of maturational age. In addition to highlighting independent regulation of various elements of the signal transduction cascade, the studies demonstrate the potential for LTH to program the fetus for cerebrovascular and other disease as an adult.
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Affiliation(s)
- Lawrence D Longo
- Center for Perinatal Biology, Department of Physiology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA.
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Lin MT, Longo LD, Pearce WJ, Hessinger DA. Ca2+-activated K+ channel-associated phosphatase and kinase activities during development. Am J Physiol Heart Circ Physiol 2005; 289:H414-25. [PMID: 15708961 DOI: 10.1152/ajpheart.01079.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In ovine basilar arterial smooth muscle cells (SMCs), the fetal "big" Ca2+-activated K+ (BK) channel activity is significantly greater and has a lower Ca2+ setpoint than BK channels from adult cells. In the present study, we tested the hypothesis that these differences result from developmentally regulated phosphorylation of these channels. Using the patch-clamp technique and a novel in situ enzymological approach, we measured the rates and extents of changes in BK channel voltage activation from SMC inside-out patch preparations in response to selective activation and inhibition of channel-associated protein phosphatases and kinases (CAPAKs). We show that BK channel activity is modulated during development by differential phosphorylation and that the activities of CAPAKs change substantially during development. In particular, excised membrane patches from adult SMCs exhibited greater protein kinase A activity than those from a fetus. In contrast, fetal SMCs exhibited greater protein kinase G activity and phosphatase activity than adult SMCs. These findings extend our previous observation that the BK channel Ca2+ setpoint differs significantly in adult and fetal cerebrovascular myocytes and suggest a biochemical mechanism for this difference. In addition, these findings suggest that the functional stoichiometry of CAPAKs varies significantly during development and that such variation may be a hitherto unrecognized mechanism of ion channel regulation.
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Affiliation(s)
- Mike T Lin
- Center for Perinatal Biology, School of Medicine, Loma Linda Univ., Loma Linda, CA 92350, USA
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15
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Tammaro P, Smith AL, Hutchings SR, Smirnov SV. Pharmacological evidence for a key role of voltage-gated K+ channels in the function of rat aortic smooth muscle cells. Br J Pharmacol 2004; 143:303-17. [PMID: 15326038 PMCID: PMC1575342 DOI: 10.1038/sj.bjp.0705957] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 07/01/2004] [Accepted: 07/15/2004] [Indexed: 11/09/2022] Open
Abstract
The role of voltage-dependent (I(K(v))) and large conductance Ca(2+)-activated (BK(Ca)) K(+) currents in the function of the rat aorta was investigated using specific BK(Ca) and K(V) channel inhibitors in single rat aortic myocytes (RAMs) with patch-clamp technique and in endothelium-denuded aortic rings with isometric tension measurements. The whole-cell K(+) currents were recorded in RAMs dialysed with 200 and 444 nm Ca(2+) and in perforated-patch configuration. Electrophysiological analysis demonstrated that I(K(v)) appeared at >/=-40 mV, while BK(Ca) (isolated using 1 microm paxilline) were seen positive to -20 mV in all conditions. Voltage-dependent characteristics, but not maximal conductance, of I(K(v)) was significantly altered in increased [Ca(2+)](i). Correolide (1 microm) (a K(V)1 channel blocker) did not inhibit the I(K(v)), whereas millimolar concentration of TEA (IC(50)=3.1+/-0.6 mm, n=5) and 4-aminopyridine (4-AP, IC(50)=5.9+/-1.9 mm, n=7) suppressed I(K(v)). These results and immunocytochemical analysis suggest the K(V)2.1 channel to be a molecular correlate for I(K(v)). In nonstimulated aortic rings 1-5 mm TEA and 4-AP (inhibitors of I(K(v))), but not paxilline (1 microm), caused contraction. The frequency of contractile responses to TEA and 4-AP was increased in the presence of 10 mm KCl, which itself did not significantly affect the aortic basal tone. Phenylephrine (15-40 nm) induced sustained tension with superimposed slow oscillatory contractions (termed OWs). OWs were blocked by diltiazem, ryanodine and cyclopiazonic acid, suggesting the involvement of L-type Ca(2+) channels and ryanodine-sensitive Ca(2+) stores in this process. TEA and 4-AP, but not IbTX, paxilline or correolide, increased the duration and amplitude of OWs, indicating that I(K(v)) is involved in the control of oscillatory activity. In conclusion, our findings suggest that the K(V)2.1-mediated I(K(v)), and not BK(Ca), plays an important role in the regulation of the excitability and contractility of rat aorta.
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MESH Headings
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/pathology
- Aorta, Thoracic/physiology
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Electrophysiology/methods
- Immunochemistry/methods
- Indoles/pharmacology
- Male
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Patch-Clamp Techniques/methods
- Peptides/pharmacology
- Potassium Channels, Calcium-Activated/drug effects
- Potassium Channels, Calcium-Activated/physiology
- Potassium Channels, Voltage-Gated/drug effects
- Potassium Channels, Voltage-Gated/genetics
- Potassium Channels, Voltage-Gated/metabolism
- Protein Isoforms
- Rats
- Rats, Wistar
- Tetraethylammonium/pharmacology
- Triterpenes/pharmacology
- United Kingdom
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- Paolo Tammaro
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY
| | - Amy L Smith
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY
| | - Simon R Hutchings
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY
| | - Sergey V Smirnov
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY
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16
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Geary GG, Osol GJ, Longo LD. Development affects in vitro vascular tone and calcium sensitivity in ovine cerebral arteries. J Physiol 2004; 558:883-96. [PMID: 15131239 PMCID: PMC1665020 DOI: 10.1113/jphysiol.2003.056945] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We have shown recently that development from neonatal to adult life affects cerebrovascular tone of mouse cerebral arteries through endothelium-derived vasodilatory mechanisms. The current study tested the hypothesis that development from fetal to adult life affects cerebral artery vascular smooth muscle (VSM) [Ca(2+)](i) sensitivity and tone through a mechanism partially dependent upon endothelium-dependent signalling. In pressurized resistance sized cerebral arteries ( approximately 150 microm) from preterm (95 +/- 2 days gestation (95 d)) and near-term (140 +/- 2 days gestation (140 d)) fetuses, and non-pregnant adults, we measured vascular diameter (microm) and [Ca(2+)](i) (nm) as a function of intravascular pressure. We repeated these studies in the presence of inhibition of nitric oxide synthase (NOS; with l-NAME), cyclo-oxygenase (COX; with indomethacin) and endothelium removal (E-). Cerebrovasculature tone (E+) was greater in arteries from 95 d fetuses and adults compared to 140 d sheep. Ca(2+) sensitivity was similar in 95 d fetuses and adults, but much lower in 140 d fetuses. Removal of endothelium resulted in a reduction in lumen diameter as a function of pressure (greater tone) in all treatment groups. [Ca(2+)](i) sensitivity differences among groups were magnified after E-. NOS inhibition decreased diameter as a function of pressure in each age group, with a significant increase in [Ca(2+)](i) to pressure ratio only in the 140 d fetuses. Indomethacin increased tone and increased [Ca(2+)](i) in the 140 d fetuses, but not the other age groups. Development from near-term to adulthood uncovered an interaction between NOS- and COX-sensitive substances that functioned to modulate artery diameter but not [Ca(2+)](i). This study suggests that development is associated with significant alterations in cerebral vascular smooth muscle (VSM), endothelium, NOS and COX responses to intravascular pressure. We speculate that these changes have important implications in the regulation of cerebral blood flow in the developing organism.
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Affiliation(s)
- Greg G Geary
- Department of Physiology and Pharmacology, Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA 92407, USA.
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17
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Zhao Y, Long W, Zhang L, Longo LD. Extracellular signal-regulated kinases and contractile responses in ovine adult and fetal cerebral arteries. J Physiol 2003; 551:691-703. [PMID: 12816972 PMCID: PMC2343231 DOI: 10.1113/jphysiol.2003.046128] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Accumulating evidence suggests that extracellular signal-regulated kinases (ERK1/2) play a key role in regulating vascular tone. To test the hypotheses that ERK1/2 modulate cerebral artery agonist-induced contraction, and that this changes with developmental age, we measured both total and phosphorylated ERK1/2 in adult and fetal ovine cerebral arteries. In middle cerebral arteries (MCA) we also examined tension and [Ca2+]i responses to phenylephrine (PHE), in the absence and presence of the ERK1/2 inhibitor U-0126 and the mitogen-activated protein kinase kinase (MAPKK or MEK) inhibitor PD-98059. In the fetus, but not adult, U-0126 potentiated PHE-induced contraction. In both age groups, inhibition by U-0126, but not PD-98059, decreased the PHE-induced [Ca2+]i increase; in fact for adult, this eliminated any significant [Ca2+]i increase. In turn in the adult, but not fetus, protein kinase C (PKC) inhibition by staurosporine (3 x 10(-8) M) prior to ERK1/2 inhibition by U-0126 (10(-5) M) prevented this elimination of [Ca2+]i increase. In adult and fetal cerebral arteries basal total ERK1/2 levels were similar. However, in fetal arteries the basal phosphorylated ERK1/2 levels were significantly less than in adult. In fetal, but not adult, cerebral arteries, 10(-6)-10(-4) M PHE increased ERK1/2 phosphorylation in a concentration- and time-dependent manner. The ERK1/2 inhibitor U-0126, but not the MEK inhibitor PD-98059, lowered basal activated ERK1/2 levels in vessels of both age groups. These results suggest that basal levels of phosphorylated ERK1/2 play an important role in suppressing Ca2+ sensitivity, perhaps by PKC inhibition. The developmental increase in cerebral artery basal phosphorylated ERK levels from fetus to adult, suggests a transition in the regulation of contraction from Ca2+ sensitivity in the fetal arteries to Ca2+ concentration in the adult vessels.
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Affiliation(s)
- Yu Zhao
- Center for Perinatal Biology, Departments of Physiology and Pharmacology, and Obstetrics and Gynecology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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Lin MT, Hessinger DA, Pearce WJ, Longo LD. Developmental differences in Ca2+-activated K+ channel activity in ovine basilar artery. Am J Physiol Heart Circ Physiol 2003; 285:H701-9. [PMID: 12689856 DOI: 10.1152/ajpheart.00138.2003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A primary determinant of vascular smooth muscle (VSM) tone and contractility is the resting membrane potential, which, in turn, is influenced heavily by K+ channel activity. Previous studies from our laboratory and others have demonstrated differences in the contractility of cerebral arteries from near-term fetal and adult animals. To test the hypothesis that these contractility differences result from maturational changes in voltage-gated K+ channel function, we compared this function in VSM myocytes from adult and fetal sheep cerebral arteries. The primary current-carrying, voltage-gated K+ channels in VSM myocytes are the large conductance Ca2+-activated K+ channels (BKCa) and voltage-activated K+ (KV) channels. We observed that at voltage-clamped membrane potentials of +60 mV in perforated whole cell studies, the normalized outward current densities in fetal myocytes were >30% higher than in those of the adult (P < 0.05) and that these were predominantly due to iberiotoxin-sensitive currents from BKCa channels. Excised, insideout membrane patches revealed nearly identical unitary conductances and Hill coefficients for BKCa channels. The plot of log intracellular [Ca2+] ([Ca2+]i) versus voltage for half-maximal activation (V(1/2)) yielded linear and parallel relationships, and the change in V(1/2) for a 10-fold change in [Ca2+] was also similar. Channel activity increased e-fold for a 19 +/- 2-mV depolarization for adult myocytes and for an 18 +/- 1-mV depolarization for fetal myocytes (P > 0.05). However, the relationship between BKCa open probability and membrane potential had a relative leftward shift for the fetal compared with adult myocytes at different [Ca2+]i. The [Ca2+] for half-maximal activation (i.e., the calcium set points) at 0 mV were 8.8 and 4.7 microM for adult and fetal myocytes, respectively. Thus the increased BKCa current density in fetal myocytes appears to result from a lower calcium set point.
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Affiliation(s)
- Mike T Lin
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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19
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Long W, Zhang L, Longo LD. Fetal and adult cerebral artery K(ATP) and K(Ca) channel responses to long-term hypoxia. J Appl Physiol (1985) 2002; 92:1692-701. [PMID: 11896039 DOI: 10.1152/japplphysiol.01110.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-altitude long-term hypoxia (LTH) alters cerebral vascular contractile and relaxation responses in both fetus and adult. We tested the hypotheses that LTH-mediated vascular responses were secondary to altered K+ channel function and that in the fetus these responses differ from those of the adult. In middle cerebral arteries (MCA) from both nonpregnant adult and fetal (approximately 140 days gestation) sheep, which were either acclimatized to high altitude (3,820 m) or sea-level controls, we measured norepinephrine (NE)-induced contractions and intracellular Ca2+ concentration ([Ca2+]i) simultaneously, in the presence or absence of different K+ channel openers or blockers. In adult MCA, LTH was associated with approximately 20% decrease in NE-induced tension and [Ca2+]i, with a significant increase in Ca2+ sensitivity. In contrast, in fetal MCA, LTH failed to affect significantly NE-induced contraction or [Ca2+]i but significantly decreased the ATP-sensitive K+ (K(ATP)) channel and Ca2+-activated K+ (K(Ca)) channel-mediated relaxation. The significant effect of K(ATP) and K(Ca) channel activators on the relaxation responses and the fact that K+ channels play a key role in myogenic tone support the hypotheses that K+ channels play an important role in hypoxia-mediated responses. These results also support the hypothesis of significant developmental differences with maturation from fetus to adult.
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Affiliation(s)
- Wen Long
- Center for Perinatal Biology, Department of Physiology, Loma Linda University, School of Medicine, Loma Linda, California 92350, USA.
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20
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Teng GQ, Nauli SM, Brayden JE, Pearce WJ. Maturation alters the contribution of potassium channels to resting and 5HT-induced tone in small cerebral arteries of the sheep. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 133:81-91. [PMID: 11882339 DOI: 10.1016/s0165-3806(01)00304-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
To address the hypothesis that maturation alters the contribution of K-channels to resting and agonist-induced tone in small cerebral arteries, second branch middle cerebral arteries (approximately 200 microm) were taken from term fetal (139-141 days gestation) and adult sheep, denuded of endothelium, and mounted in myographs. After determination of length-tension relations, the arteries were stretched to 55, 100, and 145% of optimum length. At each level of stretch, contractile responses to 5 mM 4-aminopyridine (4-AP, voltage-sensitive K-channel blocker), 100 nM iberiotoxin (calcium-sensitive K-channel blocker), 10 microM glibenclamide (ATP-sensitive K-channel blocker), or 10 microM Ba(2+) (inward rectifier K-channel blocker) were recorded. In separate experiments, concentration--response relations were determined for 5-HT in the presence and absence of each of the four K-channel blockers at the same concentrations. Both 4-AP and iberiotoxin produced stretch-dependent contractions of greater magnitude in adult (37% for 4-AP and 43% for iberiotoxin at 100% optimum) than in fetal (5% for 4-AP and 7% for iberiotoxin at 100% optimum) arteries. 4-AP also enhanced the pD(2) for 5-HT in adult (from 7.15 to 7.49), but not in fetal, arteries. Conversely, glibenclamide attenuated the pD(2) for 5-HT in fetal (from 7.02 to 6.71), but not in adult, arteries. Iberiotoxin enhanced the pD(2) for 5-HT in both fetal (from 7.05 to 7.51) and adult (from 7.15 to 7.75) arteries. In addition, iberiotoxin enhanced maximum responses to 5-HT (from 59 to 82%) in adult but not fetal arteries. Finally, 4-AP enhanced the maximum responses to 5-HT in both fetal (from 67 to 85%) and adult (from 59 to 79%) arteries. These results indicate that maturation modulates the contribution of K(V), K(Ca), and K(ATP), but not K(IR) channels to basal and/or 5HT-induced cerebrovascular tone, and demonstrate that K(V) and K(Ca) channels are coupled to stretch-sensitive receptors, and that K(V) and K(Ca) limit contractile responses to 5-HT. To the extent that changes in pD(2) values reflect changes in agonist--ligand interactions, the data also suggest that K(V), K(Ca), and K(ATP) channels may possibly influence ligand--receptor binding for 5-HT.
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Affiliation(s)
- Guo Qi Teng
- Center for Perinatal Biology, Department of Physiology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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21
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Affiliation(s)
- Heimo Ehmke
- Institut für Physiologie, Universität Hamburg, D-20246 Hamburg, Germany.
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