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Thengchaisri N, Kuo L, Hein TW. H 2O 2 Mediates VEGF- and Flow-Induced Dilations of Coronary Arterioles in Early Type 1 Diabetes: Role of Vascular Arginase and PI3K-Linked eNOS Uncoupling. Int J Mol Sci 2022; 24:ijms24010489. [PMID: 36613929 PMCID: PMC9820654 DOI: 10.3390/ijms24010489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/17/2022] [Accepted: 12/24/2022] [Indexed: 12/29/2022] Open
Abstract
In diabetes, the enzyme arginase is upregulated, which may compete with endothelial nitric oxide (NO) synthase (eNOS) for their common substrate L-arginine and compromise NO-mediated vasodilation. However, this eNOS uncoupling can lead to superoxide production and possibly vasodilator hydrogen peroxide (H2O2) formation to compensate for NO deficiency. This hypothesis was tested in coronary arterioles isolated from pigs with 2-week diabetes after streptozocin injection. The NO-mediated vasodilation induced by flow and VEGF was abolished by NOS inhibitor L-NAME and phosphoinositide 3-kinase (PI3K) inhibitor wortmannin but was not affected by arginase inhibitor Nω-hydroxy-nor-L-arginine (nor-NOHA) or H2O2 scavenger catalase in control pigs. With diabetes, this vasodilation was partially blunted, and the remaining vasodilation was abolished by catalase and wortmannin. Administration of L-arginine or nor-NOHA restored flow-induced vasodilation in an L-NAME sensitive manner. Diabetes did not alter vascular superoxide dismutase 1, catalase, and glutathione peroxidase mRNA levels. This study demonstrates that endothelium-dependent NO-mediated coronary arteriolar dilation is partially compromised in early type 1 diabetes by reducing eNOS substrate L-arginine via arginase activation. It appears that upregulated arginase contributes to endothelial NO deficiency in early diabetes, but production of H2O2 during PI3K-linked eNOS uncoupling likely compensates for and masks this disturbance.
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Affiliation(s)
- Naris Thengchaisri
- Department of Medical Physiology, Cardiovascular Research Institute, School of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand
| | - Lih Kuo
- Department of Medical Physiology, Cardiovascular Research Institute, School of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA
- Correspondence: (L.K.); (T.W.H.)
| | - Travis W. Hein
- Department of Medical Physiology, Cardiovascular Research Institute, School of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA
- Correspondence: (L.K.); (T.W.H.)
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2
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Coronary Microvascular Dysfunction in Diabetes Mellitus: Pathogenetic Mechanisms and Potential Therapeutic Options. Biomedicines 2022; 10:biomedicines10092274. [PMID: 36140374 PMCID: PMC9496134 DOI: 10.3390/biomedicines10092274] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/04/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
Diabetic patients are frequently affected by coronary microvascular dysfunction (CMD), a condition consisting of a combination of altered vasomotion and long-term structural change to coronary arterioles leading to impaired regulation of blood flow in response to changing cardiomyocyte oxygen requirements. The pathogenesis of this microvascular complication is complex and not completely known, involving several alterations among which hyperglycemia and insulin resistance play particularly central roles leading to oxidative stress, inflammatory activation and altered barrier function of endothelium. CMD significantly contributes to cardiac events such as angina or infarction without obstructive coronary artery disease, as well as heart failure, especially the phenotype associated with preserved ejection fraction, which greatly impact cardiovascular (CV) prognosis. To date, no treatments specifically target this vascular damage, but recent experimental studies and some clinical investigations have produced data in favor of potential beneficial effects on coronary micro vessels caused by two classes of glucose-lowering drugs: glucagon-like peptide 1 (GLP-1)-based therapy and inhibitors of sodium-glucose cotransporter-2 (SGLT2). The purpose of this review is to describe pathophysiological mechanisms, clinical manifestations of CMD with particular reference to diabetes, and to summarize the protective effects of antidiabetic drugs on the myocardial microvascular compartment.
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3
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Sabe SA, Feng J, Sellke FW, Abid MR. Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature. Am J Physiol Heart Circ Physiol 2022; 322:H819-H841. [PMID: 35333122 PMCID: PMC9018047 DOI: 10.1152/ajpheart.00603.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/21/2022] [Accepted: 03/21/2022] [Indexed: 12/16/2022]
Abstract
Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.
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Affiliation(s)
- Sharif A Sabe
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Jun Feng
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - Frank W Sellke
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
| | - M Ruhul Abid
- Cardiovascular Research Center, Rhode Island Hospital, Providence, Rhode Island
- Division of Cardiothoracic Surgery, Alpert Medical School of Brown University and Rhode Island Hospital, Providence, Rhode Island
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4
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Huang K, Luo X, Zhong Y, Deng L, Feng J. New insights into the role of melatonin in diabetic cardiomyopathy. Pharmacol Res Perspect 2022; 10:e00904. [PMID: 35005848 PMCID: PMC8929360 DOI: 10.1002/prp2.904] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 11/25/2021] [Indexed: 12/13/2022] Open
Abstract
Diabetic cardiovascular complications and impaired cardiac function are considered to be the main causes of death in diabetic patients worldwide, especially patients with type 2 diabetes mellitus (T2DM). An increasing number of studies have shown that melatonin, as the main product secreted by the pineal gland, plays a vital role in the occurrence and development of diabetes. Melatonin improves myocardial cell metabolism, reduces vascular endothelial cell death, reverses microcirculation disorders, reduces myocardial fibrosis, reduces oxidative and endoplasmic reticulum stress, regulates cell autophagy and apoptosis, and improves mitochondrial function, all of which are the characteristics of diabetic cardiomyopathy (DCM). This review focuses on the role of melatonin in DCM. We also discuss new molecular findings that might facilitate a better understanding of the underlying mechanism. Finally, we propose potential new therapeutic strategies for patients with T2DM.
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Affiliation(s)
- Keming Huang
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Xianling Luo
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Yi Zhong
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Li Deng
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Jian Feng
- Department of Cardiology, The Affiliated Hospital of Southwest Medical University, Luzhou, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
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5
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Frederick NE, Mitchell R, Hein TW, Bagher P. Morphological and pharmacological characterization of the porcine popliteal artery: A novel model for study of lower limb arterial disease. Microcirculation 2019; 26:e12527. [PMID: 30597676 DOI: 10.1111/micc.12527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/06/2018] [Accepted: 12/26/2018] [Indexed: 12/17/2022]
Abstract
OBJECTIVE This study was undertaken to characterize structural and pharmacological properties of the pig popliteal artery in order to develop a novel system for the examination of lower limb blood flow regulation in a variety of cardiovascular pathologies, such as diabetes-induced peripheral artery disease. METHODS Popliteal arteries were isolated from streptozocin-induced diabetic pigs or age-matched saline-injected control pigs for morphological study using transmission electron microscopy and for examination of vasoreactivity to pharmacological agents using wire myography. RESULTS Transmission electron microscopy of the porcine popliteal artery wall revealed the presence of endothelial cell-smooth muscle cell interactions (myoendothelial junctions) and smooth muscle cell-smooth muscle cell interactions, for which we have coined the term "myo-myo junctions." These myo-myo junctions were shown to feature plaques indicative of connexin expression. Further, the pig popliteal artery was highly responsive to a variety of vasoconstrictors including norepinephrine, phenylephrine, and U46619, and vasodilators including acetylcholine, adenosine 5'-[β-thio] diphosphate, and bradykinin. Finally, 2 weeks after streptozocin-induced diabetes, the normalized vasoconstriction of the pig popliteal artery to norepinephrine was unaltered compared to control. CONCLUSIONS The pig popliteal artery displays structural and pharmacological properties that might prove useful in future studies of diabetes-associated peripheral artery disease and other lower limb cardiovascular diseases.
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Affiliation(s)
- Norman E Frederick
- Department of Medical Physiology, College of Medicine, Texas A&M Health Science Center, Temple, Texas
| | - Ray Mitchell
- Department of Medical Physiology, College of Medicine, Texas A&M Health Science Center, Temple, Texas
| | - Travis W Hein
- Department of Medical Physiology, College of Medicine, Texas A&M Health Science Center, Temple, Texas
| | - Pooneh Bagher
- Department of Medical Physiology, College of Medicine, Texas A&M Health Science Center, Temple, Texas
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6
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Sorop O, van den Heuvel M, van Ditzhuijzen NS, de Beer VJ, Heinonen I, van Duin RWB, Zhou Z, Koopmans SJ, Merkus D, van der Giessen WJ, Danser AHJ, Duncker DJ. Coronary microvascular dysfunction after long-term diabetes and hypercholesterolemia. Am J Physiol Heart Circ Physiol 2016; 311:H1339-H1351. [PMID: 27591223 DOI: 10.1152/ajpheart.00458.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/01/2016] [Indexed: 02/07/2023]
Abstract
Coronary microvascular dysfunction (CMD) has been proposed as an important component of diabetes mellitus (DM)- and hypercholesterolemia-associated coronary artery disease (CAD). Previously we observed that 2.5 mo of DM and high-fat diet (HFD) in swine blunted bradykinin (BK)-induced vasodilation and attenuated endothelin (ET)-1-mediated vasoconstriction. Here we studied the progression of CMD after 15 mo in the same animal model of CAD. Ten male swine were fed a HFD in the absence (HFD, n = 5) or presence of streptozotocin-induced DM (DM + HFD, n = 5). Responses of small (∼300-μm-diameter) coronary arteries to BK, ET-1, and the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine were examined in vitro and compared with those of healthy (Normal) swine (n = 12). Blood glucose was elevated in DM + HFD (17.6 ± 4.5 mmol/l) compared with HFD (5.1 ± 0.4 mmol/l) and Normal (5.8 ± 0.6 mmol/l) swine, while cholesterol was markedly elevated in DM + HFD (16.8 ± 1.7 mmol/l) and HFD (18.1 ± 2.6 mmol/l) compared with Normal (2.1 ± 0.2 mmol/l) swine (all P < 0.05). Small coronary arteries showed early atherosclerotic plaques in HFD and DM + HFD swine. Surprisingly, DM + HFD and HFD swine maintained BK responsiveness compared with Normal swine due to an increase in NO availability relative to endothelium-derived hyperpolarizing factors. However, ET-1 responsiveness was greater in HFD and DM + HFD than Normal swine (both P < 0.05), resulting mainly from ETB receptor-mediated vasoconstriction. Moreover, the calculated vascular stiffness coefficient was higher in DM + HFD and HFD than Normal swine (both P < 0.05). In conclusion, 15 mo of DM + HFD, as well as HFD alone, resulted in CMD. Although the overall vasodilation to BK was unperturbed, the relative contributions of NO and endothelium-derived hyperpolarizing factor pathways were altered. Moreover, the vasoconstrictor response to ET-1 was enhanced, involving the ETB receptors. In conjunction with our previous study, these findings highlight the time dependence of the phenotype of CMD.
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Affiliation(s)
- Oana Sorop
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands.,Netherlands Heart Institute, Utrecht, The Netherlands; and
| | - Mieke van den Heuvel
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands.,Department of Internal Medicine, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Nienke S van Ditzhuijzen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Vincent J de Beer
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ilkka Heinonen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Richard W B van Duin
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Zhichao Zhou
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Sietse J Koopmans
- Livestock Research, Wageningen University and Research Center, Wageningen, The Netherlands
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Wim J van der Giessen
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands.,Netherlands Heart Institute, Utrecht, The Netherlands; and
| | - A H Jan Danser
- Department of Internal Medicine, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Dirk Jan Duncker
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical Center, Rotterdam, The Netherlands;
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7
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Li W, Lv J, Wu J, Zhou X, Jiang L, Zhu X, Tu Q, Tang J, Liu Y, He A, Zhong Y, Xu Z. Maternal high-salt diet altered PKC/MLC20 pathway and increased ANG II receptor-mediated vasoconstriction in adult male rat offspring. Mol Nutr Food Res 2016; 60:1684-94. [PMID: 26991838 DOI: 10.1002/mnfr.201500998] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 02/06/2016] [Accepted: 02/09/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Weisheng Li
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Juanxiu Lv
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Jue Wu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Xiuwen Zhou
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Lin Jiang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Xiaolin Zhu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Qing Tu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Jiaqi Tang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Yanping Liu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Axin He
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Yuan Zhong
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Zhice Xu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
- Center for Prenatal Biology, Loma Linda University, CA, USA
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8
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Protein kinase C in enhanced vascular tone in diabetes mellitus. Int J Cardiol 2014; 174:230-42. [DOI: 10.1016/j.ijcard.2014.04.117] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/03/2014] [Accepted: 04/09/2014] [Indexed: 12/24/2022]
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Leblanc AJ, Chen B, Dougherty PJ, Reyes RA, Shipley RD, Korzick DH, Muller-Delp JM. Divergent effects of aging and sex on vasoconstriction to endothelin in coronary arterioles. Microcirculation 2014. [PMID: 23198990 DOI: 10.1111/micc.12028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The risk for cardiovascular disease increases with advancing age; however, the chronological development of heart disease differs in males and females. The purpose of this study was to determine whether age-induced alterations in responses of coronary arterioles to the endogenous vasoconstrictor, endothelin, are sex-specific. METHODS Coronary arterioles were isolated from young and old male and female rats to assess vasoconstrictor responses to endothelin (ET), and ETa and ETb receptor inhibitors were used to assess receptor-specific signaling. RESULTS In intact arterioles from males, ET-induced vasoconstriction was reduced with age, whereas age increased vasoconstrictor responses to ET in intact arterioles from female rats. In intact arterioles from both sexes, blockade of either ETa or ETb eliminated age-related differences in responses to ET; however, denudation of arterioles from both sexes revealed age-related differences in ETa-mediated vasoconstriction. In arterioles from male rats, ETa receptor protein decreased, whereas ETb receptor protein increased with age. In coronary arterioles from females, neither ETa nor ETb receptor protein changed with age, suggesting age-related changes in ET signaling occur downstream of ET receptors. CONCLUSIONS Thus, aging-induced alterations in responsiveness of the coronary resistance vasculature to endothelin are sex-specific, possibly contributing to sexual dimorphism in the risk of cardiovascular disease with advancing age.
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Affiliation(s)
- Amanda J Leblanc
- Center for Cardiovascular and Respiratory Sciences, School of Medicine, West Virginia University, Morgantown, WV, USA
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10
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Pearson JT, Jenkins MJ, Edgley AJ, Sonobe T, Joshi M, Waddingham MT, Fujii Y, Schwenke DO, Tsuchimochi H, Yoshimoto M, Umetani K, Kelly DJ, Shirai M. Acute Rho-kinase inhibition improves coronary dysfunction in vivo, in the early diabetic microcirculation. Cardiovasc Diabetol 2013; 12:111. [PMID: 24059472 PMCID: PMC3734116 DOI: 10.1186/1475-2840-12-111] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 07/30/2013] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVES Activation of RhoA/Rho-kinase (ROCK) is increasingly implicated in acute vasospasm and chronic vasoconstriction in major organ systems. Therefore we aimed to ascertain whether an increase in ROCK activity plays a role in the deterioration of coronary vascular function in early stage diabetes. METHODS Synchrotron radiation microangiography was used to determine in vivo coronary responses in diabetic (3 weeks post streptozotocin 65 mg/kg ip) and vehicle treated male Sprague-Dawley rats (n = 8 and 6). Changes in vessel number and calibre during vasodilator stimulation before and after blockade of nitric oxide synthase and cyclooxygenase were compared between rats. Acute responses to ROCK inhibitor, fasudil (10 mg/kg iv) was evaluated. Further, perivascular and myocardial fibrosis, arterial intimal thickening were assessed by histology, and capillary density, nitrotyrosine and ROCK1/2 expressions were evaluated by immunohistochemical staining. RESULTS Diabetic rats had significantly elevated plasma glucose (P < 0.001 vs control), but did not differ in fibrotic scores, media to lumen ratio, capillary density or baseline visible vessel number or calibre. Responses to acetylcholine and sodium nitroprusside stimulation were similar between groups. However, in comparison to control rats the diabetic rats showed more segmental constrictions during blockade, which were not completely alleviated by acetylcholine, but were alleviated by fasudil. Further, second order vessel branches in diabetic rats were significantly more dilated relative to baseline (37% vs 12% increase, P < 0.05) after fasudil treatment compared to control rats, while visible vessel number increased in both groups. ROCK2 expression was borderline greater in diabetic rat hearts (P < 0.053). CONCLUSIONS We found that ahead of the reported decline in coronary endothelial vasodilator function in diabetic rats there was moderate elevation in ROCK expression, more widespread segmental constriction when nitric oxide and prostacyclin production were inhibited and notably, increased calibre in second and third order small arteries-arterioles following ROCK inhibition. Based on nitrotyrosine staining oxidative stress was not significantly elevated in early diabetic rats. We conclude that tonic ROCK mediated vasoconstriction contributes to coronary vasomotor tone in early diabetes.
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Affiliation(s)
- James T Pearson
- Department of Physiology, Monash University, Melbourne, Australia
- Monash Biomedical Imaging Facility, Melbourne, Australia
- Australian Synchrotron, Melbourne, Australia
| | - Mathew J Jenkins
- Department of Physiology, Monash University, Melbourne, Australia
- Department of Medicine, St Vincent’s Hospital, University of Melbourne, Melbourne, Australia
| | - Amanda J Edgley
- Department of Physiology, Monash University, Melbourne, Australia
- Department of Medicine, St Vincent’s Hospital, University of Melbourne, Melbourne, Australia
| | - Takashi Sonobe
- National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Mandar Joshi
- The Ritchie Centre, Monash Institute of Medical Research, Melbourne, Australia
| | - Mark T Waddingham
- Department of Physiology, Monash University, Melbourne, Australia
- Department of Medicine, St Vincent’s Hospital, University of Melbourne, Melbourne, Australia
| | - Yutaka Fujii
- National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Daryl O Schwenke
- Department of Physiology, Otago University, Dunedin, New Zealand
| | | | - Misa Yoshimoto
- National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Keiji Umetani
- Japan Synchrotron Radiation Research Institute, Harima, Japan
| | - Darren J Kelly
- Department of Medicine, St Vincent’s Hospital, University of Melbourne, Melbourne, Australia
| | - Mikiyasu Shirai
- National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
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11
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Vetri F, Chavez R, Xu HL, Paisansathan C, Pelligrino DA. Complex modulation of the expression of PKC isoforms in the rat brain during chronic type 1 diabetes mellitus. Brain Res 2012; 1490:202-9. [PMID: 23103504 DOI: 10.1016/j.brainres.2012.10.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 10/06/2012] [Accepted: 10/16/2012] [Indexed: 10/27/2022]
Abstract
We previously demonstrated that chronic hyperglycemia has a detrimental influence on neurovascular coupling in the brain-an effect linked to an alteration in the protein kinase C (PKC)-mediated phosphorylation pattern. Moreover, the activity of PKC was increased, in diabetic rat brain, in a tissue fraction composed primarily of the superficial glia limitans and pial vessels, but trended toward a decrease in cerebral cortical gray matter. However, that study did not examine the expression patterns of PKC isoforms in the rat brain. Thus, in a rat model of streptozotocin (STZ)-induced chronic type 1 diabetes mellitus (T1DM), and in non-diabetic (ND) controls, two hypotheses were addressed. First, chronic T1DM is accompanied by changes in the expression of PKC-α, βII, γ, δ, and ε Second, those changes differ when comparing cerebral cortex and glio-pial tissue. In addition, we analyzed the expression of a form of PKC-γ, phosphorylated on threonine 514 (pT514-PKC-γ), as well as the receptor for activated C kinase 1 (RACK1). The expression pattern of different PKC isoforms was altered in a complex and tissue-specific manner during chronic hyperglycemia. Notably, in the gray matter, PKC-α expression significantly decreased, while pT514-PKC-γ expression increased. However, PKC-βII, -γ, -δ, -ε, and RACK1 expressions did not change. Conversely, in glio-pial tissue, PKC-α and RACK1 were upregulated, whereas PKC-γ, pT514-PKC-γ, and PKC-ε were downregulated. PKC-βII, and PKC-δ, were unchanged. These findings suggest that the PKC activity increase previously seen in the glio-pial tissue of diabetic rats may be due to the selective upregulation of PKC-α, and ultimately lead to the impairment of neurovascular coupling.
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Affiliation(s)
- Francesco Vetri
- Neuroanesthesia Research Laboratory, Department of Anesthesiology, University of Illinois, Chicago, IL 60612, USA.
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12
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Ergul A. Endothelin-1 and diabetic complications: focus on the vasculature. Pharmacol Res 2011; 63:477-82. [PMID: 21292003 DOI: 10.1016/j.phrs.2011.01.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 01/25/2011] [Indexed: 01/24/2023]
Abstract
Diabetes is not only an endocrine but also a vascular disease. Cardiovascular complications are the leading cause of morbidity and mortality associated with diabetes. Diabetes affects both large and small vessels and hence diabetic complications are broadly classified as microvascular (retinopathy, nephropathy and neuropathy) and macrovascular (heart disease, stroke and peripheral arterial disease) complications. Endothelial dysfunction, defined as an imbalance of endothelium-derived vasoconstrictor and vasodilator substances, is a common denominator in the pathogenesis and progression of both macro and microvascular complications. While the pathophysiology of diabetic complications is complex, endothelin-1 (ET-1), a potent vasoconstrictor with proliferative, profibrotic, and proinflammatory properties, may contribute to many facets of diabetic vascular disease. This review will focus on the effects of ET-1 on function and structure of microvessels (retina, skin and mesenteric arteries) and macrovessels (coronary and cerebral arteries) and also discuss the relative role(s) of endothelin A (ET(A)) and ET(B) receptors in mediating ET-1 actions.
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Affiliation(s)
- Adviye Ergul
- Department of Physiology, Medical College of Georgia, Program in Clinical and Experimental Therapeutics, University of Georgia College of Pharmacy and Charlie Norwood Veterans Affairs Medical Center, 1120 15th St. CA2094, Augusta, GA 30912, USA.
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Matsumoto T, Ozawa Y, Taguchi K, Kobayashi T, Kamata K. Diabetes-associated changes and role of N epsilon-(carboxymethyl)lysine in big ET-1-induced coronary vasoconstriction. Peptides 2010; 31:346-53. [PMID: 19962413 DOI: 10.1016/j.peptides.2009.11.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 11/26/2009] [Accepted: 11/29/2009] [Indexed: 11/17/2022]
Abstract
Using perfused hearts from streptozotocin-induced long-term diabetic rats, we studied the coronary vasoconstrictor effect of the endothelin-1 (ET-1) precursor big ET-1 and also whether this response was modulated by N(epsilon)-(carboxymethyl)lysine (CML; a representative advanced glycation end product that is implicated in the pathogenesis of diabetic vasculopathy). The big ET-1-induced vasoconstriction (a) developed more rapidly (i.e., was greater in the first 30 min) in the diabetic group than in the age-matched controls, and (b) in each group was largely suppressed by phosphoramidon [nonselective endothelin-converting enzyme (ECE)/neutral endopeptidase (NEP) inhibitor] or CGS35066 (selective ECE inhibitor), but not by thiorphan (selective NEP inhibitor). The ET-1 release occurring after treatment with big ET-1, which was greater in diabetic coronary arteries than in the controls, was reduced by CGS35066. The dose-response curve for ET-1 was shifted to the left in the diabetics, so that at some lower doses of ET-1 the vasoconstriction was greater than in the controls. CML enhanced big ET-1- or ET-1-induced vasoconstriction in the controls, but not in the diabetics. Finally, the plasma level of CML was higher in diabetic than in control rats. These findings suggest (a) that the increased responsiveness to big ET-1 shown by diabetic coronary arteries may be attributable both to a more rapid conversion of big ET-1 to ET-1 (by ECE), allowing it to exert its contractile activity, and to an increased vascular sensitivity to ET-1, and (b) that CML may be at least partly responsible for the diabetes-associated enhancement of big ET-1-mediated coronary vasoconstriction.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
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14
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Ivey ME, Osman N, Little PJ. Endothelin-1 signalling in vascular smooth muscle: pathways controlling cellular functions associated with atherosclerosis. Atherosclerosis 2008; 199:237-47. [PMID: 18436225 DOI: 10.1016/j.atherosclerosis.2008.03.006] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 03/04/2008] [Accepted: 03/10/2008] [Indexed: 12/16/2022]
Abstract
Atherosclerosis is the primary ischaemic vascular condition underlying a majority of cardiovascular disease related deaths. Endothelin-1 is a vasoactive peptide agent upregulated in atherosclerosis and in conjunction with its G protein-coupled receptors exerts diverse actions on all cells of the vasculature in particular vascular smooth muscle cells (VSMC). The effects of endothelin-1 include cell proliferation, migration and contraction, and the induction of extracellular matrix components and growth factors. VSMC as the major component of the neointima in atherosclerotic plaques accordingly play a key role in atherogenesis. In this review we examine classic and novel signalling pathways activated by endothelin-1 in VSMC (including phospholipase C, adenylate cyclase, Rho kinase, transactivation of receptor tyrosine kinases, mitogen activated protein kinase cascades and beta-arrestin) and their likely impact on the development and progression of atherosclerosis.
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Affiliation(s)
- Melanie E Ivey
- Cell Biology of Diabetes Laboratory, Baker Heart Research Institute, Melbourne, Victoria, Australia
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15
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Dong L, Zheng YM, Van Riper D, Rathore R, Liu QH, Singer HA, Wang YX. Functional and molecular evidence for impairment of calcium-activated potassium channels in type-1 diabetic cerebral artery smooth muscle cells. J Cereb Blood Flow Metab 2008; 28:377-86. [PMID: 17684520 DOI: 10.1038/sj.jcbfm.9600536] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cerebral vascular dysfunction and associated diseases often occur in type-1 diabetes, but the underlying mechanisms are largely unknown. In this study, we sought to determine whether big-conductance, Ca(2+)-activated K(+) (BK) channels were impaired in vascular (cerebral artery) smooth muscle cells (CASMCs) from streptozotocin-induced type-1 diabetic mice using patch clamp, molecular biologic, and genetic approaches. Our data indicate that the frequency and amplitude of spontaneous transient outward currents (STOCs) are significantly decreased, whereas the activity of spontaneous Ca(2+) sparks is increased, in diabetic CASMCs. The sensitivity of BK channels to voltage, Ca(2+), and the specific inhibitor iberiotoxin are all reduced in diabetic myocytes. Diabetic mice show increased myogenic tone and decreased contraction in response to iberiotoxin in cerebral arteries and elevated blood pressure. The expression of the BK channel beta1, but not alpha-subunit protein, is markedly decreased in diabetic cerebral arteries. Diabetic impairment of BK channel activity is lost in CASMCs from BK channel beta1-subunit gene deletion mice. In conclusion, the BK channel beta1-subunit is impaired in type-1 diabetic vascular SMCs, resulting in increased vasoconstriction and elevated blood pressure, thereby contributing to vascular diseases in type-1 diabetes.
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Affiliation(s)
- Ling Dong
- Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208, USA
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16
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Jiang J, Yuen V, Xiang H, McNeill JH. Improvement in cardiac function of diabetic rats by bosentan is not associated with changes in the activation of PKC isoforms. Mol Cell Biochem 2006; 282:177-85. [PMID: 16317525 DOI: 10.1007/s11010-006-1926-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 08/09/2005] [Indexed: 11/25/2022]
Abstract
We previously demonstrated that chronic treatment with the mixed endothelin A and B (ET(A) and ET(B)) receptor blocker bosentan improved isolated working heart function in streptozotocin (STZ) diabetic rats. Endothelin-1 (ET-1) peptide levels, ET-1 mRNA and ET(A) and ET(B) receptor mRNA were all increased in diabetic hearts, but were unaffected by bosentan treatment, indicating that the beneficial effects of bosentan on heart appear to be on downstream effectors of ET-1 and ET receptors rather than the ET-1 system itself. Stimulation of ET-1 receptors leads to increased activation of protein kinase C (PKC), which is associated with PKC translocation from the cytosol to the membrane. Persistent activation of specific PKC isoforms has been proposed to contribute to diabetic cardiomyopathy. The purpose of this study was to determine whether chronic treatment with bosentan influences the activation of PKC isoforms in hearts from diabetic rats. Male Wistar rats were divided into four groups: control, bosentan-treated control, diabetic, and bosentan-treated diabetic. Diabetes was induced by the intravenous injection of 60 mg/kg streptozotocin. One week later, treatment with bosentan (100 mg/kg/day) by oral gavage was begun and continued for 10 weeks. The heart was then removed, homogenized, separated into soluble (cytosolic) and particulate (membrane) fractions and PKC isoform content in each fraction was determined by Western blotting. PKC alpha, beta2, delta, epsilon and zeta were all detected in hearts from both control and diabetic rats. However, no change in the levels or distribution between the soluble and particulate fractions of any of these isoforms could be detected in chronic diabetic hearts compared to control, whether untreated or treated with bosentan. These observations indicate that bosentan does not improve cardiac performance in STZ diabetic rats by affecting the activation of PKC isoforms.
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Affiliation(s)
- Jihong Jiang
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, British Columbia V6T 1Z3, Canada
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17
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Bulhak AA, Sjöquist PO, Xu CB, Edvinsson L, Pernow J. Protection against myocardial ischaemia/reperfusion injury by PPAR-alpha activation is related to production of nitric oxide and endothelin-1. Basic Res Cardiol 2006; 101:244-52. [PMID: 16411023 DOI: 10.1007/s00395-005-0580-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 11/17/2005] [Accepted: 11/29/2005] [Indexed: 11/30/2022]
Abstract
BACKGROUND Ligands of peroxisome proliferator-activated receptor alpha (PPAR-alpha) have been shown to reduce ischaemia/reperfusion injury. The mechanisms behind this effect are not well known. We hypothesized that activation of PPAR-alpha exerts cardioprotection via a mechanism related to nitric oxide (NO) and endothelin-1 (ET-1). METHODS Five groups of anaesthetized open-chest Sprague-Dawley rats were given the PPAR-alpha agonist WY 14643 1 mg/kg (WY; n = 7), dimethyl sulfoxide (DMSO, vehicle for WY; n = 6), the combination of WY and the NO synthase inhibitor N-nitro-L-arginine (L-NNA, 2 mg/kg) (n = 7), L-NNA only (n = 8) or 0.9% sodium chloride (NaCl, vehicle for DMSO and L-NNA; n = 8) i.v. before a 30 min period of coronary artery occlusion followed by 2 h of reperfusion. Infarct size (IS), eNOS and iNOS protein and ET-1 mRNA expression were determined. RESULTS There were no haemodynamic differences between the groups during the experiment. The IS was 78 +/- 3% of the area at risk in the DMSO group and 77 +/- 2% in the NaCl group (P = NS). WY reduced IS to 56 +/- 3% (P < 0.001 vs. DMSO group). When WY was administered in combination with L-NNA the cardioprotective effect was abolished (IS 73 +/- 3%, P < 0.01 vs. WY 14643). L-NNA did not affect IS per se (78 +/- 2%, P = NS). The expression of eNOS but not iNOS protein in ischaemic myocardium from rats was increased in the group given WY (P < 0.05). ET-1 mRNA levels were lower in the ischaemic myocardium following WY administration. CONCLUSION The results suggest that the PPAR-alpha activation protects the rat myocardium against ischaemia/ reperfusion injury via a mechanism related to production of NO, and possibly ET-1.
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Affiliation(s)
- A A Bulhak
- Department of Cardiology, Karolinska University Hospital, Solna, 171 76 Stockholm, Sweden.
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18
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Mueed I, Zhang L, MacLeod KM. Role of the PKC/CPI-17 pathway in enhanced contractile responses of mesenteric arteries from diabetic rats to alpha-adrenoceptor stimulation. Br J Pharmacol 2006; 146:972-82. [PMID: 16205724 PMCID: PMC1751237 DOI: 10.1038/sj.bjp.0706398] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Protein kinase C (PKC) may contribute to enhanced contractile responses of arteries from streptozotocin-diabetic rats to stimulation of G-protein coupled receptors. This was investigated by comparing the effects of PKC inhibitors on contractile responses of mesenteric arteries from diabetic and age-matched control rats to noradrenaline (NA) and endothelin-1 (ET-1). The effects of NA and ET-1 on the distribution of three isoforms of PKC implicated in contraction were also determined. In addition, the effect of NA on phosphorylation of CPI-17, a substrate for PKC, was investigated. Contractile responses of endothelium-denuded arteries from diabetic rats to NA were enhanced, but were normalized by PKC inhibition. In contrast, contractile responses to ET-1 were not significantly different, and were blocked to a similar extent by PKC inhibition, in arteries from control and diabetic rats.NA produced only a small increase in particulate levels of PKCepsilon in control arteries (to 125+/-8% of levels in untreated arteries), but a significant increase in particulate PKCalpha (to 190+/-22%) and a much greater increase in particulate PKCepsilon (to 230+/-19%) in arteries from diabetic rats. ET-1 increased particulate PKCalpha and epsilon to a similar extent in arteries from control and diabetic rats.NA significantly enhanced CPI-17 phosphorylation from a basal level of 22+/-10 to 71+/-7% of total in arteries from diabetic rats, and this was prevented by PKC inhibition. NA had no detectable effect on CPI-17 phosphorylation in arteries from control rats. These data suggest that NA-induced activation of PKC and CPI-17, its downstream target, is selectively enhanced in arteries from diabetic rats, and mediates the enhanced contractile responses to this agonist.
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Affiliation(s)
- Irem Mueed
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, Canada V6T 1Z3
| | - Lili Zhang
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, Canada V6T 1Z3
| | - Kathleen M MacLeod
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, Canada V6T 1Z3
- Author for correspondence: interchange.ubc.ca
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Zhao X, Li X, Trusa S, Olson SC. Angiotensin type 1 receptor is linked to inhibition of nitric oxide production in pulmonary endothelial cells. ACTA ACUST UNITED AC 2005; 132:113-22. [PMID: 16242794 DOI: 10.1016/j.regpep.2005.09.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 09/08/2005] [Indexed: 11/22/2022]
Abstract
We previously demonstrated that angiotensin II (Ang II) stimulates an increase in nitric oxide synthase (NOS) mRNA levels, eNOS protein expression and NO production via the type 2 (AT2) receptor, whereas signaling via the type 1 (AT1) receptor negatively regulates NO production in bovine pulmonary artery endothelial cells (BPAECs). In the present study, we investigated the components of the AT1 receptor-linked signaling pathway(s) that are involved in the downregulation of eNOS protein expression in BPAECs. Treatment of BPAECs with either AT1 receptor antagonists or an anti-AT1 receptor antibody induced eNOS protein expression. Furthermore, intracellular delivery of GP-Antagonist-2A, an inhibitor of Galphaq proteins, and treatment of BPAECs with U73122, a phosphatidylinositol-phospholipase C (PLC)-specific inhibitor, enhanced eNOS protein expression. Treatment of BPAECs with the cell-permeable calcium chelator, BAPTA/AM, increased eNOS protein expression at 8 h, while increasing intracellular calcium with either thapsigargin or A23187 prevented Ang II-induced eNOS protein expression. Phorbol myristate acetate (PMA), a protein kinase C (PKC) activator, completely prevented Ang II-stimulated eNOS protein expression at 8 h, whereas depletion of PKC by long-term treatment with PMA, induced eNOS protein expression. Treatment of BPAECs with a PKCalpha-specific inhibitor or transfection of BPAECs with an anti-PKCalpha neutralizing antibody stimulated eNOS protein expression. Conversely, rottlerin, a PKCdelta specific isoform inhibitor had no effect on basal or Ang II-stimulated eNOS protein expression. Moreover, treatment of BPAECs with U73122, BAPTA/AM and PKCalpha-specific inhibitors increased NO production at 8 h. In conclusion, Ang II downregulates eNOS protein expression via an AT1 receptor-linked pathway involving Galphaq/PLC/calcium/PKCalpha signaling pathway in BPAECs.
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Affiliation(s)
- Xiangmin Zhao
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
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20
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Jiang J, Zhang L, Macleod KM, McNeill JH. Effect of chronic endothelin blockade on PKC isoform distribution in mesenteric arteries from diabetic rats. Mol Cell Biochem 2005; 280:69-75. [PMID: 16311906 DOI: 10.1007/s11010-005-8053-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 05/27/2005] [Indexed: 12/01/2022]
Abstract
Hemodynamic changes, including increased vasoconstriction and reduced blood flow have been detected in both human diabetic patients and in animal models of diabetes. We previously demonstrated that the endothelin (ET) system was upregulated and involved in mediating the exaggerated vasoconstrictor responses in superior mesenteric artery (SMA) from diabetic rats. Chronic treatment of diabetic rats with the dual endothelin receptor antagonist, bosentan abolished the enhanced contractile responses in diabetic SMA. The biological actions of ET-1 have been shown to be coupled to the hydrolysis of phosphotidylinositol 4,5-biphosphate and phosphotidylcholine and the subsequent production of diacylglycerol (DAG). DAG is an activator of the classical and novel isoforms of PKC. Increases in PKC activity, associated with translocation of specific PKC isoforms from the cytosol to the membrane, have been implicated in the vasoconstrictor effect of ET-1. The goal of the present study was to determine whether chronic treatment of diabetic rats with bosentan influences the activation of specific PKC isoforms in SMA from diabetic rats. Elevated levels of PKCbeta2 in both the cytosol and membrane fractions and PKCepsilon in the membrane fraction were detected in SMA from diabetic rats. However, neither the levels nor the distribution between the cytosol and membrane fractions of any of these PKC isoforms were affected by the treatment of the diabetic rats with bosentan. These observations indicate that bosentan improves vascular reactivity in STZ-diabetic rats by mechanisms other than correction of increased activities of PKC isoforms.
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Affiliation(s)
- Jihong Jiang
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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21
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Katakam PVG, Snipes JA, Tulbert CD, Mayanagi K, Miller AW, Busija DW. Impaired endothelin-induced vasoconstriction in coronary arteries of Zucker obese rats is associated with uncoupling of [Ca2+]i signaling. Am J Physiol Regul Integr Comp Physiol 2005; 290:R145-53. [PMID: 16322351 DOI: 10.1152/ajpregu.00405.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although insulin resistance (IR) is a major risk factor for coronary artery disease, little is known about the regulation of coronary vascular tone in IR by endothelin-1 (ET-1). We examined ET-1 and PGF(2alpha)-induced vasoconstriction in isolated small coronary arteries (SCAs; approximately 250 microM) of Zucker obese (ZO) rats and control Zucker lean (ZL) rats. ET-1 response was assessed in the absence and presence of endothelin type A (ET(A); BQ-123), type B (ET(B); BQ-788), or both receptor inhibitors. ZO arteries displayed reduced contraction to ET-1 compared with ZL arteries. In contrast, PGF(2alpha) elicited similar vasoconstriction in both groups. ET(A) inhibition diminished the ET-1 response in both groups. ET(B) inhibition alone or in combination with ET(A) blockade, however, restored the ET-1 response in ZO arteries to the level of ZL arteries. Similarly, inhibition of endothelial nitric oxide (NO) synthase with N(omega)-nitro-l-arginine methyl ester (l-NAME) enhanced the contraction to ET-1 and abolished the difference between ZO and ZL arteries. In vascular smooth muscle cells from ZO, ET-1-induced elevation of myoplasmic intracellular free calcium concentration ([Ca2+]i) (measured by fluo-4 AM fluorescence), and maximal contractions were diminished compared with ZL, both in the presence and absence of l-NAME. However, increases in [Ca2+]i elicited similar contractions of the vascular smooth muscle cells in both groups. Analysis of protein and total RNA from SCA of ZO and ZL revealed equal expression of ET-1 and the ET(A) and ET(B) receptors. Thus coronary arteries from ZO rats exhibit reduced ET-1-induced vasoconstriction resulting from increased ET(B)-mediated generation of NO and diminished elevation of myoplasmic [Ca2+]i.
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Affiliation(s)
- Prasad V G Katakam
- Deptartment of Physiology and Pharmacology, Wake Forest University Health Sciences, Hanes 1050, Medical Center Blvd., Winston-Salem, NC 27157, USA
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22
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Korzick DH, Rishel ME, Bowles DK. Exercise and hypercholesterolemia produce disparate shifts in coronary PKC expression. Med Sci Sports Exerc 2005; 37:381-8. [PMID: 15741835 DOI: 10.1249/01.mss.0000155698.76417.4c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Sedentary lifestyle and high-fat, high-cholesterol diets are each associated with elevated risk for coronary heart disease (CHD); however, the mechanisms by which they increase risk are unclear. Specific PKC isoforms have been implicated in the development of CHD, regulation of coronary vasoreactivity, as well as exercise-induced cardioprotection. Thus, diet and physical inactivity may increase CHD risk by altering coronary protein kinase C (PKC) isoform profiles. PURPOSE To determine whether coronary PKC isoform profiles are altered in a model of early CHD and whether exercise can prevent these changes. METHODS Male and female Yucatan miniature swine were either fed a normal (NF) or high-fat (HF) diet (8 vs 46% kilocalories from fat) and remained sedentary (Sed) or were treadmill-trained (Ex) at 75% of; VO2max (6 mph, 60 min) for 16 wk. Groups were as follows: NFSed (N=8/N=7), NFEx (N=8/N=7), HFSed (N=8/N=7), and HFEx (N=8/N=7). Western blotting was performed on right coronary conduit artery (CCA) segments (>1 mm I.D.) to measure total protein levels of PKC-alpha, -betaI, -betaII, -delta, -epsilon, and -zeta. RESULTS HF diet increased total cholesterol by more than sixfold with no increase in triglycerides. Hypercholesterolemia increased PKC-betaII and -epsilon protein levels in CCA of both male and female pig; Ex had no effect on this response. Ex-induced increases in PKC-betaI, PKC-delta, and PKC-zeta were observed in HF male pigs. Female pigs had higher baseline amounts of PKC-alpha (25%), PKC-betaI (33%), PKC-betaII (39%), and PKC-epsilon (29%), whereas male pigs had higher amounts of PKC-delta (308%). Further analyses revealed a direct relationship between androgens and PKC-delta levels. CONCLUSION Hypercholesterolemia and exercise exert disparate effects on coronary PKC expression. Observed sex differences in PKC protein profiles may also contribute to altered cardiovascular risk patterns in males versus females.
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Affiliation(s)
- Donna H Korzick
- Noll Physiological Research Center, Intercollege Program in Physiology, The Penn State University, University Park, PA 16802, USA.
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Kim MH, Harris NR, Korzick DH, Tarbell JM. Control of the arteriolar myogenic response by transvascular fluid filtration. Microvasc Res 2004; 68:30-7. [PMID: 15219418 DOI: 10.1016/j.mvr.2004.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Indexed: 11/16/2022]
Abstract
Mechanisms of the myogenic response have not been completely established. We hypothesized that transvascular fluid filtration from plasma across smooth muscle cells (SMC) and into the surrounding interstitium helps regulate arteriolar myogenic tone. Arteriolar diameters in the rat mesentery were monitored before and following vascular occlusion with a glass micropipette. Arteriolar occlusion not only gave an increase in hydrostatic pressure that initiated myogenic constriction upstream of the pipette, but also allowed measurement of fluid filtration rate by monitoring the movement of vascular red blood cells. A statistically significant correlation (P < 0.001) existed between basal myogenic tone and fluid filtration. Additionally, the myogenic response was attenuated by 47% +/- 7% (N = 10) when an osmotic solution of albumin or albumin plus Ficoll was infused into the bloodstream to decrease fluid filtration by 53% +/- 3%. Moreover, the same inhibition of myogenic tone was found in isolated, cannulated rat soleus muscle arterioles when filtration was osmotically attenuated by intravascular dextran. Taken together, these results are consistent with the hypothesis that shear stress on arteriolar smooth muscle, induced by transvascular fluid filtration, is a contributing factor that helps control myogenic tone.
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Affiliation(s)
- Min-ho Kim
- Department of Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
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