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Martín-Aragón Baudel M, Hong J, Hell JW, Nieves-Cintrón M, Navedo MF. Mechanisms of Vascular Ca V1.2 Channel Regulation During Diabetic Hyperglycemia. Handb Exp Pharmacol 2023; 279:41-58. [PMID: 36598607 DOI: 10.1007/164_2022_628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Diabetes is a leading cause of disability and mortality worldwide. A major underlying factor in diabetes is the excessive glucose levels in the bloodstream (e.g., hyperglycemia). Vascular complications directly result from this metabolic abnormality, leading to disabling and life-threatening conditions. Dysfunction of vascular smooth muscle cells is a well-recognized factor mediating vascular complications during diabetic hyperglycemia. The function of vascular smooth muscle cells is exquisitely controlled by different ion channels. Among the ion channels, the L-type CaV1.2 channel plays a key role as it is the main Ca2+ entry pathway regulating vascular smooth muscle contractile state. The activity of CaV1.2 channels in vascular smooth muscle is altered by diabetic hyperglycemia, which may contribute to vascular complications. In this chapter, we summarize the current understanding of the regulation of CaV1.2 channels in vascular smooth muscle by different signaling pathways. We place special attention on the regulation of CaV1.2 channel activity in vascular smooth muscle by a newly uncovered AKAP5/P2Y11/AC5/PKA/CaV1.2 axis that is engaged during diabetic hyperglycemia. We further describe the pathophysiological implications of activation of this axis as it relates to myogenic tone and vascular reactivity and propose that this complex may be targeted for developing therapies to treat diabetic vascular complications.
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Affiliation(s)
| | - Junyoung Hong
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA.
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2
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Wang M, Li S, Liu H, Liu M, Zhang J, Wu Y, Xiao C, Huang H. Large-conductance Ca 2 +-activated K + channel β1-subunit maintains the contractile phenotype of vascular smooth muscle cells. Front Cardiovasc Med 2022; 9:1062695. [PMID: 36568562 PMCID: PMC9780463 DOI: 10.3389/fcvm.2022.1062695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022] Open
Abstract
Background Vascular smooth muscle cells (VSMCs) phenotype switching is very important during the pathogenesis and progression of vascular diseases. However, it is not well understood how normal VSMCs maintain the differentiated state. The large-conductance Ca2+-activated K+ (BKCa) channels are widely expressed in VSMCs and regulate vascular tone. Nevertheless, there is limited understanding of the role of the BKCa channel in modulation of the VSMC phenotype. Methods and results We assessed BKCa channel expression levels in normal and injured carotid arteries from rats of the balloon-injury model. A strong decrease of BKCa-β1 was seen in the injured carotid arteries, accompanied by a parallel decrease of the VSMC contractile markers. BKCa-β1 in primary rat aortic VSMCs was decreased with the increase of passage numbers and the stimulation of platelet-derived growth factor (PDGF)-BB. Conversely, transforming growth factor β upregulated BKCa-β1. Meanwhile, the BKCa-β1 level was positively associated with the levels of VSMC contractile proteins. Intravenous injection of PDGF-BB induced downregulation of BKCa-β1 expression in the carotid arteries. Knockdown of BKCa-β1 favored VSMC dedifferentiation, characterized by altered morphology, abnormal actin fiber organization, decreased contractile proteins expression and reduced contractile ability. Furthermore, the resultant VSMC dedifferentiated phenotype rendered increased proliferation, migration, enhanced inflammatory factors levels, and matrix metalloproteinases activity. Studies using primary cultured aortic VSMCs from human recapitulated key findings. Finally, protein level of BKCa-β1 was reduced in human atherosclerotic arteries. Conclusion BKCa-β1 is important in the maintenance of the contractile phenotype of VSMCs. As a novel endogenous defender that prevents pathological VSMC phenotype switching, BKCa-β1 may serve as a potential therapeutic target for treating vascular diseases including post-injury restenosis and atherosclerosis.
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Affiliation(s)
- Meili Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Shuanglei Li
- Division of Adult Cardiac Surgery, Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Hongshan Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Mingyuan Liu
- Department of Vascular Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jin Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Yang Wu
- Division of Adult Cardiac Surgery, Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Cangsong Xiao
- Division of Adult Cardiac Surgery, Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China,Cangsong Xiao,
| | - Haixia Huang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,*Correspondence: Haixia Huang,
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3
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Lu T, Lee HC. Coronary Large Conductance Ca 2+-Activated K + Channel Dysfunction in Diabetes Mellitus. Front Physiol 2021; 12:750618. [PMID: 34744789 PMCID: PMC8567020 DOI: 10.3389/fphys.2021.750618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/14/2021] [Indexed: 11/24/2022] Open
Abstract
Diabetes mellitus (DM) is an independent risk of macrovascular and microvascular complications, while cardiovascular diseases remain a leading cause of death in both men and women with diabetes. Large conductance Ca2+-activated K+ (BK) channels are abundantly expressed in arteries and are the key ionic determinant of vascular tone and organ perfusion. It is well established that the downregulation of vascular BK channel function with reduced BK channel protein expression and altered intrinsic BK channel biophysical properties is associated with diabetic vasculopathy. Recent efforts also showed that diabetes-associated changes in signaling pathways and transcriptional factors contribute to the downregulation of BK channel expression. This manuscript will review our current understandings on the molecular, physiological, and biophysical mechanisms that underlie coronary BK channelopathy in diabetes mellitus.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Hon-Chi Lee
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
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4
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Sharma S, Brown CE. Microvascular basis of cognitive impairment in type 1 diabetes. Pharmacol Ther 2021; 229:107929. [PMID: 34171341 DOI: 10.1016/j.pharmthera.2021.107929] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/23/2021] [Accepted: 05/19/2021] [Indexed: 02/07/2023]
Abstract
The complex computations of the brain require a constant supply of blood flow to meet its immense metabolic needs. Perturbations in blood supply, even in the smallest vascular networks, can have a profound effect on neuronal function and cognition. Type 1 diabetes is a prevalent and insidious metabolic disorder that progressively and heterogeneously disrupts vascular signalling and function in the brain. As a result, it is associated with an array of adverse vascular changes such as impaired regulation of vascular tone, pathological neovascularization and vasoregression, capillary plugging and blood brain barrier disruption. In this review, we highlight the link between microvascular dysfunction and cognitive impairment that is commonly associated with type 1 diabetes, with the aim of synthesizing current knowledge in this field.
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Affiliation(s)
- Sorabh Sharma
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Craig E Brown
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada; Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
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5
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Nieves-Cintrón M, Flores-Tamez VA, Le T, Baudel MMA, Navedo MF. Cellular and molecular effects of hyperglycemia on ion channels in vascular smooth muscle. Cell Mol Life Sci 2021; 78:31-61. [PMID: 32594191 PMCID: PMC7765743 DOI: 10.1007/s00018-020-03582-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 06/10/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022]
Abstract
Diabetes affects millions of people worldwide. This devastating disease dramatically increases the risk of developing cardiovascular disorders. A hallmark metabolic abnormality in diabetes is hyperglycemia, which contributes to the pathogenesis of cardiovascular complications. These cardiovascular complications are, at least in part, related to hyperglycemia-induced molecular and cellular changes in the cells making up blood vessels. Whereas the mechanisms mediating endothelial dysfunction during hyperglycemia have been extensively examined, much less is known about how hyperglycemia impacts vascular smooth muscle function. Vascular smooth muscle function is exquisitely regulated by many ion channels, including several members of the potassium (K+) channel superfamily and voltage-gated L-type Ca2+ channels. Modulation of vascular smooth muscle ion channels function by hyperglycemia is emerging as a key contributor to vascular dysfunction in diabetes. In this review, we summarize the current understanding of how diabetic hyperglycemia modulates the activity of these ion channels in vascular smooth muscle. We examine underlying mechanisms, general properties, and physiological relevance in the context of myogenic tone and vascular reactivity.
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Affiliation(s)
- Madeline Nieves-Cintrón
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Víctor A Flores-Tamez
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Thanhmai Le
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA.
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6
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Tang Q, Zheng YM, Song T, Reyes-García J, Wang C, Wang YX. Inhibition of big-conductance Ca 2+-activated K + channels in cerebral artery (vascular) smooth muscle cells is a major novel mechanism for tacrolimus-induced hypertension. Pflugers Arch 2020; 473:53-66. [PMID: 33033891 DOI: 10.1007/s00424-020-02470-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/17/2020] [Accepted: 09/30/2020] [Indexed: 01/10/2023]
Abstract
Tacrolimus (TAC, also called FK506), a common immunosuppressive drug used to prevent allograft rejection in transplant patients, is well known to alter the functions of blood vessels. In this study, we sought to determine whether chronic treatment of TAC could inhibit the activity of big-conductance Ca2+-activated K+ (BK) channels in vascular smooth muscle cells (SMCs), leading to hypertension. Our data reveal that the activity of BK channels was inhibited in cerebral artery SMCs (CASMCs) from mice after intraperitoneal injection of TAC once a day for 4 weeks. The voltage sensitivity, Ca2+ sensitivity, and open time of single BK channels were all decreased. In support, BK channel β1-, but not α-subunit protein expression was significantly decreased in cerebral arteries. In TAC-treated mice, application of norepinephrine induced stronger vasoconstriction in both cerebral and mesenteric arteries as well as a larger [Ca2+]i in CASMCs. Chronic treatment of TAC, similar to BK channel β1-subunit knockout (KO), resulted in hypertension in mice, but did not cause a further increase in blood pressure in BK channel β1-subunit KO mice. Moreover, BK channel activity in CASMCs was negatively correlated with blood pressure. Our findings provide novel evidence that TAC inhibits BK channels by reducing the channel β1-subunit expression and functions in vascular SMCs, leading to enhanced vasoconstriction and hypertension.
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Affiliation(s)
- Qiang Tang
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA.,Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA.
| | - Tengyao Song
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA
| | - Jorge Reyes-García
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA
| | - Chen Wang
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA.
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Yang Z, Song T, Truong L, Reyes-García J, Wang L, Zheng YM, Wang YX. Important Role of Sarcoplasmic Reticulum Ca 2+ Release via Ryanodine Receptor-2 Channel in Hypoxia-Induced Rieske Iron-Sulfur Protein-Mediated Mitochondrial Reactive Oxygen Species Generation in Pulmonary Artery Smooth Muscle Cells. Antioxid Redox Signal 2020; 32:447-462. [PMID: 31456413 PMCID: PMC6987675 DOI: 10.1089/ars.2018.7652] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Aims: It is known that mitochondrial reactive oxygen species generation ([ROS]m) causes the release of Ca2+via ryanodine receptor-2 (RyR2) on the sarcoplasmic reticulum (SR) in pulmonary artery smooth muscle cells (PASMCs), playing an essential role in hypoxic pulmonary vasoconstriction (HPV). In this study, we sought to determine whether hypoxia-induced RyR2-mediated Ca2+ release may in turn promote [ROS]m in PASMCs and the underlying signaling mechanism. Results: Our data reveal that application of caffeine or norepinephrine to induce Ca2+ release increased [ROS]m in PASMCs. Likewise, exogenous Ca2+ augmented ROS generation in isolated mitochondria and at complex III from PASMCs. Inhibition of mitochondrial Ca2+ uniporter (MCU) with Ru360 attenuated agonist-induced [ROS]m. Ru360 produced a similar inhibitory effect on hypoxia-induced [ROS]m. Rieske iron-sulfur protein (RISP) gene knockdown inhibited Ca2+- and caffeine-induced [ROS]m. Inhibition of RyR2 by tetracaine or RyR2 gene knockout suppressed hypoxia-induced [ROS]m as well. Innovation: In this article, we present convincing evidence that Ca2+ release following hypoxia or RyR simulation causes a significant increase in MCU, and the increased MCU subsequently RISP-dependent [ROS]m, which provides a positive feedback mechanism to enhance hypoxia-initiated [ROS]m in PASMCs. Conclusion: Our findings demonstrate that hypoxia-induced mitochondrial ROS-dependent SR RyR2-mediated Ca2+ release increases MCU and then RISP-dependent [ROS]m in PASMCs, which may make significant contributions to HPV and associated pulmonary hypertension.
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Affiliation(s)
- Zhao Yang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York.,Department of Respiratory Medicine, Suzhou Science & Technology Town Hospital, Suzhou, China
| | - Tengyao Song
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Lillian Truong
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Jorge Reyes-García
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Lan Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
| | - Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York
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8
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Zheng J, Zhou H, Yang M, Song S, Dai Q, Ji G, Zhou Z. Reduced Ca 2+ spark activity contributes to detrusor overactivity of rats with partial bladder outlet obstruction. Aging (Albany NY) 2020; 12:4163-4177. [PMID: 32112553 PMCID: PMC7093189 DOI: 10.18632/aging.102855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 01/28/2020] [Indexed: 12/19/2022]
Abstract
We tested whether or not altered Ca2+ spark activity accounted for detrusor overactivity (DO) of Wistar rats after partial bladder outlet obstruction (PBOO). We constructed a DO model through PBOO and studied the Ca2+ spark activity of detrusor. By way of using confocal microscopy and the patch-clamp technique, Ca2+ sparks and spontaneous transient outward currents (STOCs) in detrusor myocytes were measured respectively. Our results indicated that Ca2+ spark activity and STOCs were significantly reduced in the DO detrusor myocytes compared to unafflicted control cells, and both of these had levels that were remarkably increased by applications of caffeine (10 μM), a RyR agonist, in DO myocytes. In addition, measures of detrusor contractions were also recorded by using freshly isolated detrusor strips. These results indicated that the spontaneous contraction of DO detrusor was significantly enhanced, and that the effect of caffeine (10 μM) upon detrusor contractions was reversed by applications of iberiotoxin (100 nM) which is a BK channel blocker. Western blotting (WB) analyses indicated that the levels of expression of ryanodine receptor type 2 (RyR2) and FK506 binding protein 12.6 (FKBP12.6) in bladder muscle were respectively decreased and increased in the samples from DO rats. Thus, we considered in the rat DO model wherein PBOO, the reduced Ca2+ spark activity in detrusor myocytes partly contributed to overactive detrusor contractions. The impaired Ca2+ spark activity may have resulted from decreased RyR2 expression and increased FKBP12.6 expression. Such novel findings in our research might help to provide means for better treatment outcomes for patients afflicted by bladder dysfunction.
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Affiliation(s)
- Ji Zheng
- Department of Urology, Urological Surgery Research Institute, First Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Hao Zhou
- Department of Urology, Urological Surgery Research Institute, First Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Mengjun Yang
- Department of Urology, Urological Surgery Research Institute, First Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Siji Song
- Department of Urology, Urological Surgery Research Institute, First Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Qiang Dai
- Department of Urology, Urological Surgery Research Institute, First Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Guangju Ji
- Key Laboratory of Interdisciplinary Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100049, China
| | - Zhansong Zhou
- Department of Urology, Urological Surgery Research Institute, First Affiliated Hospital, Army Medical University (Third Military Medical University), Chongqing 400038, China
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Lu T, Chai Q, Jiao G, Wang XL, Sun X, Furuseth JD, Stulak JM, Daly RC, Greason KL, Cha YM, Lee HC. Downregulation of BK channel function and protein expression in coronary arteriolar smooth muscle cells of type 2 diabetic patients. Cardiovasc Res 2020; 115:145-153. [PMID: 29850792 DOI: 10.1093/cvr/cvy137] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 05/22/2018] [Indexed: 12/20/2022] Open
Abstract
Aims Type 2 diabetes (T2D) is strongly associated with cardiovascular morbidity and mortality in patients. Vascular large conductance Ca2+-activated potassium (BK) channels, composed of four pore-forming α subunits (BK-α), and four regulatory β1 subunits (BK-β1), are densely expressed in coronary arterial smooth muscle cells (SMCs) and play an important role in regulating vascular tone and myocardial perfusion. However, the role of BK channels in coronary microvascular dysfunction of human subjects with diabetes is unclear. In this study, we examined BK channel function and protein expression, and BK channel-mediated vasodilation in freshly isolated coronary arterioles from T2D patients. Methods and results Atrial tissues were obtained from 16 patients with T2D and 25 matched non-diabetic subjects during cardiopulmonary bypass procedure. Microvessel videomicroscopy and immunoblot analysis were performed in freshly dissected coronary arterioles and inside-out single BK channel currents was recorded in enzymatically isolated coronary arteriolar SMCs. We found that BK channel sensitivity to physiological Ca2+ concentration and voltage was downregulated in the coronary arteriolar SMCs of diabetic patients, compared with non-diabetic controls. BK channel kinetics analysis revealed that there was significant shortening of the mean open time and prolongation of the mean closed time in diabetic patients, resulting in a remarkable reduction of the channel open probability. Functional studies showed that BK channel activation by dehydrosoyasaponin-1 was diminished and that BK channel-mediated vasodilation in response to shear stress was impaired in diabetic coronary arterioles. Immunoblot experiments confirmed that the protein expressions of BK-α and BK-β1 subunits were significantly downregulated, but the ratio of BK-α/BK-β1 was unchanged in the coronary arterioles of T2D patients. Conclusions Our results demonstrated for the first time that BK channel function and BK channel-mediated vasodilation were abnormal in the coronary microvasculature of diabetic patients, due to decreased protein expression and altered intrinsic properties of BK channels.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Qiang Chai
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA.,Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 89 Jingshi Road, Jinan, Shandong, PR China
| | - Guoqing Jiao
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA.,Department of Cardiovascular Surgery, Wuxi People's Hospital Affiliated to Nanjing Medical University, 299 Qingyang Road, Wuxi, Jiangsu, PR China
| | - Xiao-Li Wang
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Xiaojing Sun
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Jonathan D Furuseth
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - John M Stulak
- Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street, SW., Rochester, Minnesota, USA
| | - Richard C Daly
- Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street, SW., Rochester, Minnesota, USA
| | - Kevin L Greason
- Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street, SW., Rochester, Minnesota, USA
| | - Yong-Mei Cha
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Hon-Chi Lee
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
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Abstract
It has been reported that Sanoshashinto (SanHuangXieXinTang, 三黃瀉心湯), which is composed of Rhei Rhizoma, Scutellariae Radix, and Coptidis Rhizoma, exhibits vasorelaxant effects in vitro and lowers blood pressure of patients. Based on this discovery, in this study, a mixture containing those three materials and combinations of them were extracted with methanol, and the extracts were fractionated into different parts. Effects of all extracts and fractions on high concentration of potassium chloride (High K+)- or noradrenaline (NA)-induced contractions of isolated rat aortic rings or helical strips were examined. Qualitative and quantitative HPLC analyses of the extracts and the fractions revealed that the contents of baicalin and berberine in Sanoshashinto methanol extract (SHXXTM) were higher than those of the other constituents. All pharmacological and HPLC data were analyzed by principal component analysis (PCA) software and the results indicated that baicalin, berberine, palmatine, baicalein, and wogonoside contributed significantly to the pharmacological activity. Furthermore, spontaneously hypertensive rats (SHRs) that were orally given SHXXTM or a baicalin–berberine combination showed significantly reduced increase in the rate of systolic blood pressure (SBP) compared to the control group. These findings suggested that Sanoshashinto has significant vasorelaxant effects in vitro and antihypertensive effects in vivo, and baicalin and berberine, which were the principal constituents of Scutellariae Radix and Coptidis Rhizoma, were the main antihypertensive constituents in Sanoshashinto. It was speculated that baicalin and berberine produced vasorelaxant effects by activating the NO/cGMP pathway and that the BKCa channel and the DAG/PKC/CPI-17 pathway were also involved.
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11
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Greenstein AS, Kadir SZAS, Csato V, Sugden SA, Baylie RA, Eisner DA, Nelson MT. Disruption of Pressure-Induced Ca 2+ Spark Vasoregulation of Resistance Arteries, Rather Than Endothelial Dysfunction, Underlies Obesity-Related Hypertension. Hypertension 2019; 75:539-548. [PMID: 31865779 PMCID: PMC7055934 DOI: 10.1161/hypertensionaha.119.13540] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Supplemental Digital Content is available in the text. Obesity-related hypertension is one of the world’s leading causes of death and yet little is understood as to how it develops. As a result, effective targeted therapies are lacking and pharmacological treatment is unfocused. To investigate underlying microvascular mechanisms, we studied small artery dysfunction in a high fat–fed mouse model of obesity. Pressure-induced constriction and responses to endothelial and vascular smooth muscle agonists were studied using myography; the corresponding intracellular Ca2+ signaling pathways were examined using confocal microscopy. Principally, we observed that the enhanced basal tone of mesenteric resistance arteries was due to failure of intraluminal pressure-induced Ca2+ spark activation of the large conductance Ca2+ activated K+ potassium channel (BK) within vascular smooth muscle cells. Specifically, the uncoupling site of this mechanotransduction pathway was at the sarcoplasmic reticulum, distal to intraluminal pressure-induced oxidation of Protein Kinase G. In contrast, the vasodilatory function of the endothelium and the underlying endothelial IP-3 and TRPV4 (vanilloid 4 transient receptor potential ion channel) Ca2+ signaling pathways were not affected by the high-fat diet or the elevated blood pressure. There were no structural alterations of the arterial wall. Our work emphasizes the importance of the intricate cellular pathway by which intraluminal pressure maintains Ca2+ spark vasoregulation in the origin of obesity-related hypertension and suggests previously unsuspected avenues for pharmacological intervention.
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Affiliation(s)
- Adam S Greenstein
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | | | - Viktoria Csato
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Sarah A Sugden
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Rachael A Baylie
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - David A Eisner
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mark T Nelson
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
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12
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Abstract
The microcirculation maintains tissue homeostasis through local regulation of blood flow and oxygen delivery. Perturbations in microvascular function are characteristic of several diseases and may be early indicators of pathological changes in the cardiovascular system and in parenchymal tissue function. These changes are often mediated by various reactive oxygen species and linked to disruptions in pathways such as vasodilation or angiogenesis. This overview compiles recent advances relating to redox regulation of the microcirculation by adopting both cellular and functional perspectives. Findings from a variety of vascular beds and models are integrated to describe common effects of different reactive species on microvascular function. Gaps in understanding and areas for further research are outlined. © 2020 American Physiological Society. Compr Physiol 10:229-260, 2020.
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Affiliation(s)
- Andrew O Kadlec
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Medical Scientist Training Program, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - David D Gutterman
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Department of Medicine-Division of Cardiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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13
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Hu XQ, Song R, Romero M, Dasgupta C, Huang X, Holguin MA, Williams V, Xiao D, Wilson SM, Zhang L. Pregnancy Increases Ca 2+ Sparks/Spontaneous Transient Outward Currents and Reduces Uterine Arterial Myogenic Tone. Hypertension 2019; 73:691-702. [PMID: 30661479 DOI: 10.1161/hypertensionaha.118.12484] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Spontaneous transient outward currents (STOCs) at physiological membrane potentials of vascular smooth muscle cells fundamentally regulate vascular myogenic tone and blood flow in an organ. We hypothesize that heightened STOCs play a key role in uterine vascular adaptation to pregnancy. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep. Ca2+ sparks were measured by confocal microscopy, and STOCs were determined by electrophysiological recording in smooth muscle cells. Percentage of Ca2+ spark firing myocytes increased dramatically at the resting condition in uterine arterial smooth muscle of pregnant animals, as compared with nonpregnant animals. Pregnancy upregulated the expression of RyRs (ryanodine receptors) and significantly boosted Ca2+ spark frequency. Ex vivo treatment of uterine arteries of nonpregnant sheep with estrogen and progesterone imitated pregnancy-induced RyR upregulation. STOCs occurred at much more negative membrane potentials in uterine arterial myocytes of pregnant animals. STOCs in uterine arterial myocytes were diminished by inhibiting large-conductance Ca2+-activated K+ (BKCa) channels and RyRs, thus functionally linking Ca2+ sparks and BKCa channel activity to STOCs. Pregnancy and steroid hormone treatment significantly increased STOCs frequency and amplitude in uterine arteries. Of importance, inhibition of STOCs with RyR inhibitor ryanodine eliminated pregnancy- and steroid hormone-induced attenuation of uterine arterial myogenic tone. Thus, the present study demonstrates a novel role of Ca2+ sparks and STOCs in the regulation of uterine vascular tone and provides new insights into the mechanisms underlying uterine vascular adaptation to pregnancy.
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Affiliation(s)
- Xiang-Qun Hu
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Rui Song
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Monica Romero
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Chiranjib Dasgupta
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Xiaohui Huang
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Mark A Holguin
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - VaShon Williams
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Daliao Xiao
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Sean M Wilson
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
| | - Lubo Zhang
- From the Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA
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14
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Gojkovic-Bukarica L, Markovic-Lipkovski J, Heinle H, Cirovic S, Rajkovic J, Djokic V, Zivanovic V, Bukarica A, Novakovic R. The red wine polyphenol resveratrol induced relaxation of the isolated renal artery of diabetic rats: The role of potassium channels. J Funct Foods 2019. [DOI: 10.1016/j.jff.2018.11.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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15
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Mughal A, Sun C, O'Rourke ST. Activation of Large Conductance, Calcium-Activated Potassium Channels by Nitric Oxide Mediates Apelin-Induced Relaxation of Isolated Rat Coronary Arteries. J Pharmacol Exp Ther 2018; 366:265-273. [PMID: 29773582 PMCID: PMC6034271 DOI: 10.1124/jpet.118.248682] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/15/2018] [Indexed: 01/09/2023] Open
Abstract
Apelin increases coronary blood flow, cardiac contractility, and cardiac output. Based on these favorable hemodynamic effects, apelin and apelin-like analogs are being developed for treating heart failure and related disorders; however, the molecular mechanisms underlying apelin-induced coronary vasodilation are unknown. This study aimed to elucidate the signaling pathways by which apelin causes smooth muscle relaxation in coronary arteries. Receptors for apelin (APJ receptors) were expressed in coronary arteries, as determined by Western blot and polymerase chain reaction analyses. Immunofluorescence imaging studies identified APJ receptors on endothelial and smooth muscle cells. In isolated endothelial cells, apelin caused an increase in 4,5-diaminofluorescein fluorescence that was abolished by nitro-l-arginine (NLA) and F13A (H-Gln-Arg-Pro-Arg-Leu-Ser-His-Lys-Gly-Pro-Met-Pro-Ala-OH), an APJ receptor antagonist, consistent with increased nitric oxide (NO) production. In arterial rings, apelin caused endothelium-dependent relaxations that were abolished by NLA, F13A, and iberiotoxin. Neither oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) nor DT-2, a protein kinase G inhibitor, had any effect on apelin-induced relaxations, and apelin itself had no effect on intracellular cGMP accumulation in coronary arteries. Patch-clamp studies in isolated smooth muscle cells demonstrated that the NO donors, diethyl amine NONOate and sodium nitroprusside, caused increases in large conductance, calcium-activated potassium channel (BKCa) currents, which were inhibited by iberiotoxin but not ODQ. Thus, apelin causes endothelium-dependent relaxation of coronary arteries by stimulating endothelial APJ receptors and releasing NO, which acts in a cGMP-independent manner and increases BKCa activity in the underlying smooth muscle cells. These results provide a mechanistic basis for apelin-induced coronary vasodilation and may provide guidance for the future development of novel apelin-like therapeutic agents.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota
| | - Chengwen Sun
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota
| | - Stephen T O'Rourke
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota
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16
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Dopico AM, Bukiya AN, Jaggar JH. Calcium- and voltage-gated BK channels in vascular smooth muscle. Pflugers Arch 2018; 470:1271-1289. [PMID: 29748711 DOI: 10.1007/s00424-018-2151-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 04/27/2018] [Indexed: 02/04/2023]
Abstract
Ion channels in vascular smooth muscle regulate myogenic tone and vessel contractility. In particular, activation of calcium- and voltage-gated potassium channels of large conductance (BK channels) results in outward current that shifts the membrane potential toward more negative values, triggering a negative feed-back loop on depolarization-induced calcium influx and SM contraction. In this short review, we first present the molecular basis of vascular smooth muscle BK channels and the role of subunit composition and trafficking in the regulation of myogenic tone and vascular contractility. BK channel modulation by endogenous signaling molecules, and paracrine and endocrine mediators follows. Lastly, we describe the functional changes in smooth muscle BK channels that contribute to, or are triggered by, common physiological conditions and pathologies, including obesity, diabetes, and systemic hypertension.
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Affiliation(s)
- Alex M Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St., Memphis, TN, 38163, USA.
| | - Anna N Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St., Memphis, TN, 38163, USA
| | - Jonathan H Jaggar
- Department of Physiology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
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17
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Coucha M, Abdelsaid M, Ward R, Abdul Y, Ergul A. Impact of Metabolic Diseases on Cerebral Circulation: Structural and Functional Consequences. Compr Physiol 2018; 8:773-799. [PMID: 29687902 DOI: 10.1002/cphy.c170019] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Metabolic diseases including obesity, insulin resistance, and diabetes have profound effects on cerebral circulation. These diseases not only affect the architecture of cerebral blood arteries causing adverse remodeling, pathological neovascularization, and vasoregression but also alter the physiology of blood vessels resulting in compromised myogenic reactivity, neurovascular uncoupling, and endothelial dysfunction. Coupled with the disruption of blood brain barrier (BBB) integrity, changes in blood flow and microbleeds into the brain rapidly occur. This overview is organized into sections describing cerebrovascular architecture, physiology, and BBB in these diseases. In each section, we review these properties starting with larger arteries moving into smaller vessels. Where information is available, we review in the order of obesity, insulin resistance, and diabetes. We also tried to include information on biological variables such as the sex of the animal models noted since most of the information summarized was obtained using male animals. © 2018 American Physiological Society. Compr Physiol 8:773-799, 2018.
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Affiliation(s)
- Maha Coucha
- South University, School of Pharmacy, Savannah, Georgia, USA
| | | | - Rebecca Ward
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Yasir Abdul
- Charlie Norwood VA Medical Center, Augusta, Georgia, USA.,Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Adviye Ergul
- Charlie Norwood VA Medical Center, Augusta, Georgia, USA.,Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
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18
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Nieves-Cintrón M, Syed AU, Buonarati OR, Rigor RR, Nystoriak MA, Ghosh D, Sasse KC, Ward SM, Santana LF, Hell JW, Navedo MF. Impaired BK Ca channel function in native vascular smooth muscle from humans with type 2 diabetes. Sci Rep 2017; 7:14058. [PMID: 29070899 PMCID: PMC5656614 DOI: 10.1038/s41598-017-14565-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/11/2017] [Indexed: 01/04/2023] Open
Abstract
Large-conductance Ca2+-activated potassium (BKCa) channels are key determinants of vascular smooth muscle excitability. Impaired BKCa channel function through remodeling of BKCa β1 expression and function contributes to vascular complications in animal models of diabetes. Yet, whether similar alterations occur in native vascular smooth muscle from humans with type 2 diabetes is unclear. In this study, we evaluated BKCa function in vascular smooth muscle from small resistance adipose arteries of non-diabetic and clinically diagnosed type 2 diabetic patients. We found that BKCa channel activity opposes pressure-induced constriction in human small resistance adipose arteries, and this is compromised in arteries from diabetic patients. Consistent with impairment of BKCa channel function, the amplitude and frequency of spontaneous BKCa currents, but not Ca2+ sparks were lower in cells from diabetic patients. BKCa channels in diabetic cells exhibited reduced Ca2+ sensitivity, single-channel open probability and tamoxifen sensitivity. These effects were associated with decreased functional coupling between BKCa α and β1 subunits, but no change in total protein abundance. Overall, results suggest impairment in BKCa channel function in vascular smooth muscle from diabetic patients through unique mechanisms, which may contribute to vascular complications in humans with type 2 diabetes.
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Affiliation(s)
| | - Arsalan U Syed
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
| | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
| | - Robert R Rigor
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
| | - Matthew A Nystoriak
- Diabetes and Obesity Center, Department of Medicine, University of Louisville, Louisville, KY, 40202, USA
| | - Debapriya Ghosh
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
| | | | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Luis F Santana
- Department of Physiology & Membrane Biology, University of California, Davis, CA, 95616, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, 95616, USA.
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19
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Ma YG, Liang L, Zhang YB, Wang BF, Bai YG, Dai ZJ, Xie MJ, Wang ZW. Berberine reduced blood pressure and improved vasodilation in diabetic rats. J Mol Endocrinol 2017; 59:191-204. [PMID: 28515053 DOI: 10.1530/jme-17-0014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 05/17/2017] [Indexed: 12/14/2022]
Abstract
Hyperglycemia and hypertension are considered to be the two leading risk factors for vascular disease in diabetic patients. However, few pharmacologic agents could provide a combinational therapy for controlling hyperglycemia and hypertension at the same time in diabetes. The objectives of this study are to investigate whether berberine treatment could directly reduce blood pressure and identify the molecular mechanism underlying the vascular protection of berberine in diabetic rats. Berberine was intragastrically administered with different dosages of 50, 100 and 200 mg/kg/day to diabetic rats for 8 weeks since the injection of streptozotocin. The endothelium-dependent/-independent relaxation in middle cerebral arteries was investigated. The activity of large-conductance Ca2+-activated K+ channel (BKCa) was investigated by recording whole-cell currents, analyzing single-channel activities and assessing the expressions of α- and β1-subunit at protein or mRNA levels. Results of the study suggest that chronic administration of 100 mg/kg/day berberine not only lowered blood glucose but also reduced blood pressure and improved vasodilation in diabetic rats. Furthermore, berberine markedly increased the function and expression of BKCa β1-subunit in cerebral vascular smooth muscle cells (VSMCs) isolated from diabetic rats or when exposed to hyperglycemia condition. The present study provided initial evidences that berberine reduced blood pressure and improved vasodilation in diabetic rats by activation of BKCa channel in VSMCs, which suggested that berberine might provide a combinational therapy for controlling hyperglycemia and blood pressure in diabetes. Furthermore, our work indicated that activation of BKCa channel might be the underlying mechanism responsible for the vascular protection of berberine in diabetes.
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Affiliation(s)
- Yu-Guang Ma
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Liang Liang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Yin-Bin Zhang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Bao-Feng Wang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Yun-Gang Bai
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Zhi-Jun Dai
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Man-Jiang Xie
- Department of Aerospace PhysiologyKey Laboratory of Aerospace Medicine of Ministry of Education, Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhong-Wei Wang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
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20
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Zhao QY, Peng YB, Luo XJ, Luo X, Xu H, Wei MY, Jiang QJ, Li WE, Ma LQ, Xu JC, Liu XC, Zang DA, She YS, Zhu H, Shen J, Zhao P, Xue L, Yu MF, Chen W, Zhang P, Fu X, Chen J, Nie X, Shen C, Chen S, Chen S, Chen J, Hu S, Zou C, Qin G, Fang Y, Ding J, Ji G, Zheng YM, Song T, Wang YX, Liu QH. Distinct Effects of Ca 2+ Sparks on Cerebral Artery and Airway Smooth Muscle Cell Tone in Mice and Humans. Int J Biol Sci 2017; 13:1242-1253. [PMID: 29104491 PMCID: PMC5666523 DOI: 10.7150/ijbs.21475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/10/2017] [Indexed: 11/21/2022] Open
Abstract
The effects of Ca2+ sparks on cerebral artery smooth muscle cells (CASMCs) and airway smooth muscle cells (ASMCs) tone, as well as the underlying mechanisms, are not clear. In this investigation, we elucidated the underlying mechanisms of the distinct effects of Ca2+ sparks on cerebral artery smooth muscle cells (CASMCs) and airway smooth muscle cells (ASMCs) tone. In CASMCs, owing to the functional loss of Ca2+-activated Cl- (Clca) channels, Ca2+ sparks activated large-conductance Ca2+-activated K+ channels (BKs), resulting in a decreases in tone against a spontaneous depolarization-caused high tone in the resting state. In ASMCs, Ca2+ sparks induced relaxation through BKs and contraction via Clca channels. However, the integrated result was contraction because Ca2+ sparks activated BKs prior to Clca channels and Clca channels-induced depolarization was larger than BKs-caused hyperpolarization. However, the effects of Ca2+ sparks on both cell types were determined by L-type voltage-dependent Ca2+ channels (LVDCCs). In addition, compared with ASMCs, CASMCs had great and higher amplitude Ca2+ sparks, a higher density of BKs, and higher Ca2+ and voltage sensitivity of BKs. These differences enhanced the ability of Ca2+ sparks to decrease CASMC and to increase ASMC tone. The higher Ca2+ and voltage sensitivity of BKs in CASMCs than ASMCs were determined by the β1 subunits. Moreover, Ca2+ sparks showed the similar effects on human CASMC and ASMC tone. In conclusions, Ca2+ sparks decrease CASMC tone and increase ASMC tone, mediated by BKs and Clca channels, respectively, and finally determined by LVDCCs.
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Affiliation(s)
- Qing-Yang Zhao
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Yong-Bo Peng
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Xiao-Jing Luo
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Xi Luo
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Hao Xu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Ming-Yu Wei
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Qiu-Ju Jiang
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Wen-Er Li
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Li-Qun Ma
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Jin-Chao Xu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Xiao-Cao Liu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Dun-An Zang
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Yu-San She
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - He Zhu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Jinhua Shen
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Ping Zhao
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Lu Xue
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Meng-Fei Yu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Weiwei Chen
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
| | - Ping Zhang
- Department of Cerebral Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430032, Hubei, China
| | - Xiangning Fu
- Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430032, Hubei, China
| | - Jingyu Chen
- Wuxi &Jiangsu Key Laboratory of Organ Transplantation, Department of Cardiothoracic Surgery, Lung Transplant Group, Wuxi People's Hospital, Nanjing Medical University, Jiangsu, China
| | - Xiaowei Nie
- Wuxi &Jiangsu Key Laboratory of Organ Transplantation, Department of Cardiothoracic Surgery, Lung Transplant Group, Wuxi People's Hospital, Nanjing Medical University, Jiangsu, China
| | - Chenyou Shen
- Wuxi &Jiangsu Key Laboratory of Organ Transplantation, Department of Cardiothoracic Surgery, Lung Transplant Group, Wuxi People's Hospital, Nanjing Medical University, Jiangsu, China
| | - Shu Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430032, Hubei, China
| | - Shanshan Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430032, Hubei, China
| | - Jingcao Chen
- Department of Cerebral Surgery, Zhongnan Hospital, Wuhan University Medical College, Wuhan, 430071, Hubei, China
| | - Sheng Hu
- Department of Medical Oncology, Hubei Cancer Hospital, Wuhan, 430079, Hubei, China
| | - Chunbin Zou
- Acute Lung Injury Center of Excellence, Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, School of Medicine & School of Engineering, University of Alabama Birmingham, AL, 35294, USA
| | - Ying Fang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jiuping Ding
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Guangju Ji
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, 12208, USA
| | - Tengyao Song
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, 12208, USA
| | - Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, 12208, USA
| | - Qing-Hua Liu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China
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21
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Aleksandrowicz M, Dworakowska B, Dolowy K, Kozniewska E. Restoration of the response of the middle cerebral artery of the rat to acidosis in hyposmotic hyponatremia by the opener of large-conductance calcium sensitive potassium channels (BK Ca). J Cereb Blood Flow Metab 2017; 37:3219-3230. [PMID: 28058990 PMCID: PMC5584697 DOI: 10.1177/0271678x16685575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hyposmotic hyponatremia (the decrease of extracellular concentration of sodium ions from 145 to 121 mM and the decrease of hyposmolality from 300 to 250 mOsm/kg H2O) impairs response of the middle cerebral artery (MCA) to acetylcholine and NO donor (S-nitroso-N-acetyl-DL-penicillamine). Since acidosis activates a similar intracellular signaling pathway, the present study was designed to verify the hypothesis that the response of the MCA to acidosis is impaired during acute hyposmotic hyponatremia due to abnormal NO-related signal transduction in vascular smooth muscle cells. Studies performed on isolated, cannulated, and pressurized rat MCA revealed that hyposmotic hyponatremia impaired the response of the MCA to acidosis and this was associated with hyposmolality rather than with decreased sodium ion concentration. Response to acidosis was restored by the BKCa but not by the KATP channel activator. Patch-clamp electrophysiology performed on myocytes freshly isolated from MCAs, demonstrated that hyposmotic hyponatremia does not affect BKCa currents but decreases the voltage-dependency of the activation of the BKCa channels in the presence of a specific opener of these channels. Our study suggests that reduced sensitivity of BKCa channels in the MCA to agonists results in the lack of response of this artery to acidosis during acute hyposmotic hyponatremia.
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Affiliation(s)
- Marta Aleksandrowicz
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Beata Dworakowska
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Krzysztof Dolowy
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Ewa Kozniewska
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.,3 Department of Experimental and Clinical Physiology, Medical University of Warsaw, Warsaw, Poland
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22
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Ma YG, Wang JW, Zhang YB, Wang BF, Dai ZJ, Xie MJ, Kang HF. Salidroside improved cerebrovascular vasodilation in streptozotocin-induced diabetic rats through restoring the function of BKCa channel in smooth muscle cells. Cell Tissue Res 2017; 370:365-377. [DOI: 10.1007/s00441-017-2671-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 07/18/2017] [Indexed: 12/16/2022]
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23
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Maqoud F, Cetrone M, Mele A, Tricarico D. Molecular structure and function of big calcium-activated potassium channels in skeletal muscle: pharmacological perspectives. Physiol Genomics 2017; 49:306-317. [DOI: 10.1152/physiolgenomics.00121.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/08/2017] [Accepted: 04/10/2017] [Indexed: 11/22/2022] Open
Abstract
The large-conductance Ca2+-activated K+ (BK) channel is broadly expressed in various mammalian cells and tissues such as neurons, skeletal muscles (sarco-BK), and smooth muscles. These channels are activated by changes in membrane electrical potential and by increases in the concentration of intracellular calcium ion (Ca2+). The BK channel is subjected to many mechanisms that add diversity to the BK channel α-subunit gene. These channels are indeed subject to alternative splicing, auxiliary subunits modulation, posttranslational modifications, and protein-protein interactions. BK channels can be modulated by diverse molecules that may induce either an increase or decrease in channel activity. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, have been found to be relevant in many physiological processes. BK channel diversity is obtained by means of alternative splicing and modulatory β- and γ-subunits. The association of the α-subunit with β- or with γ-subunits can change the BK channel phenotype, functional diversity, and pharmacological properties in different tissues. In the case of the skeletal muscle BK channel (sarco-BK channel), we established that the main mechanism regulating BK channel diversity is the alternative splicing of the KCNMA1/slo1 gene encoding for the α-subunit generating different splicing isoform in the muscle phenotypes. This finding helps to design molecules selectively targeting the skeletal muscle subtypes. The use of drugs selectively targeting the skeletal muscle BK channels is a promising strategy in the treatment of familial disorders affecting muscular skeletal apparatus including hyperkalemia and hypokalemia periodic paralysis.
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Affiliation(s)
- Fatima Maqoud
- Department of Pharmacy-Drug Science, University of Bari, Bari, Italy
- Faculty of Science, Chouaib Doukkali University, El Jadida, Morocco
| | - Michela Cetrone
- Istituto Tumori Giovanni Paolo II, Istituto di Ricovero e Cura a Carattere Scientifico, National Cancer Institute, Bari, Italy; and
| | - Antonietta Mele
- Department of Pharmacy-Drug Science, University of Bari, Bari, Italy
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24
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Parajuli SP, Zheng YM, Levin R, Wang YX. Big-conductance Ca 2+-activated K + channels in physiological and pathophysiological urinary bladder smooth muscle cells. Channels (Austin) 2016; 10:355-364. [PMID: 27101440 DOI: 10.1080/19336950.2016.1180488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Contraction and relaxation of urinary bladder smooth muscle cells (UBSMCs) represent the important physiological functions of the bladder. Contractile responses in UBSMCs are regulated by a number of ion channels including big-conductance Ca2+- activated K+ (BK) channels. Great progress has been made in studies of BK channels in UBSMCs. The intent of this review is to summarize recent exciting findings with respect to the functional interactions of BK channels with muscarinic receptors, ryanodine receptors (RyRs) and inositol triphosphate receptors (IP3Rs) as well as their functional importance under normal and pathophysiological conditions. BK channels are highly expressed in UBSMCs. Activation of muscarinic M3 receptors inhibits the BK channel activity, facilitates opening of voltage-dependent Ca2+ (CaV) channels, and thereby enhances excitability and contractility of UBSMCs. Signaling molecules and regulatory mechanisms involving RyRs and IP3Rs have a significant effect on functions of BK channels and thereby regulate cellular responses in UBSMCs under normal and pathophysiological conditions including overactive bladders. Moreover, BK channels may represent a novel target for the treatment of bladder dysfunctions.
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Affiliation(s)
- Shankar P Parajuli
- a Center for Cardiovascular Sciences, Albany Medical College , Albany , NY , USA
| | - Yun-Min Zheng
- a Center for Cardiovascular Sciences, Albany Medical College , Albany , NY , USA
| | - Robert Levin
- b Stratton VA Medical Center , Albany , NY , USA
| | - Yong-Xiao Wang
- a Center for Cardiovascular Sciences, Albany Medical College , Albany , NY , USA
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25
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Krishnamoorthy-Natarajan G, Koide M. BK Channels in the Vascular System. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:401-38. [PMID: 27238270 DOI: 10.1016/bs.irn.2016.03.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Autoregulation of blood flow is essential for the preservation of organ function to ensure continuous supply of oxygen and essential nutrients and removal of metabolic waste. This is achieved by controlling the diameter of muscular arteries and arterioles that exhibit a myogenic response to changes in arterial blood pressure, nerve activity and tissue metabolism. Large-conductance voltage and Ca(2+)-dependent K(+) channels (BK channels), expressed exclusively in smooth muscle cells (SMCs) in the vascular wall of healthy arteries, play a critical role in regulating the myogenic response. Activation of BK channels by intracellular, local, and transient ryanodine receptor-mediated "Ca(2+) sparks," provides a hyperpolarizing influence on the SMC membrane potential thereby decreasing the activity of voltage-dependent Ca(2+) channels and limiting Ca(2+) influx to promote SMC relaxation and vasodilation. The BK channel α subunit, a large tetrameric protein with each monomer consisting of seven-transmembrane domains, a long intracellular C-terminal tail and an extracellular N-terminus, associates with the β1 and γ subunits in vascular SMCs. The BK channel is regulated by factors originating within the SMC or from the endothelium, perivascular nerves and circulating blood, that significantly alter channel gating properties, Ca(2+) sensitivity and expression of the α and/or β1 subunit. The BK channel thus serves as a central receiving dock that relays the effects of the changes in several such concomitant autocrine and paracrine factors and influences cardiovascular health. This chapter describes the primary mechanism of regulation of myogenic response by BK channels and the alterations to this mechanism wrought by different vasoactive mediators.
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Affiliation(s)
| | - M Koide
- University of Vermont, Burlington, VT, United States
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26
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Geng FH, Li GH, Zhang X, Zhang P, Dong MQ, Zhao ZJ, Zhang Y, Dong L, Gao F. Berberine improves mesenteric artery insulin sensitivity through up-regulating insulin receptor-mediated signalling in diabetic rats. Br J Pharmacol 2016; 173:1569-79. [PMID: 26914282 DOI: 10.1111/bph.13466] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 01/25/2016] [Accepted: 02/11/2016] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Berberine, a small molecule derived from Coptidis rhizome, has been found to be potent at lowering blood glucose and regulating lipid metabolism. Recent clinical studies have shown that berberine reduces blood pressure and increases systemic insulin sensitivity in patients with metabolic syndrome; however, the underlying mechanism is still unclear. Here, we investigated the mechanism by which berberine improves vascular insulin sensitivity in diabetic rats. EXPERIMENTAL APPROACH Diabetes was induced in male Sprague–Dawley rats by feeding a high-fat diet and administration of a low dose of streptozotocin. These diabetic rats were treated with berberine (200 mg·kg(−1)·day(−1), gavage) for 4 weeks. Vascular dilation was determined in isolated mesenteric artery rings. Effects of berberine on insulin signalling were also studied in human artery endothelial cells cultured in high glucose (25 mmol·L(−1)) and palmitate (500 μmol·L(−1)). KEY RESULTS Berberine treatment for 4 weeks significantly restored the impaired ACh- and insulin-induced vasodilatation of mesenteric arteries from diabetic rats. In isolated mesenteric artery rings, berberine (2.5–10 μmol·L(−1)) elicited dose-dependent vasodilatation and significantly enhanced insulin-induced vasodilatation. Mechanistically, berberine up-regulated phosphorylation of the insulin receptor and its downstream signalling molecules AMPK, Akt and eNOS, and increased cell viability and autophagy in cultured endothelial cells. Moreover, down-regulating insulin receptors with specific siRNA significantly attenuated berberine-induced phosphorylation of AMPK. CONCLUSIONS AND IMPLICATIONS Berberine improves diabetic vascular insulin sensitivity and mesenteric vasodilatation by up-regulating insulin receptor-mediated signalling in diabetic rats. These findings suggest berberine has potential as a preventive or adjunctive treatment of diabetic vascular complications. LINKED ARTICLES This article is part of a themed section on Chinese Innovation in Cardiovascular Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-23.
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Affiliation(s)
- Feng-Hao Geng
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Guo-Hua Li
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Xing Zhang
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Peng Zhang
- Department of Orthopedic Surgery, Urumqi General Hospital, Urumqi, China
| | - Ming-Qing Dong
- Department of Pathophysiology, The Fourth Military Medical University, Xi'an, China
| | - Zhi-Jing Zhao
- Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yuan Zhang
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Ling Dong
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Feng Gao
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China.,Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
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27
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Karlin A. Membrane potential and Ca2+ concentration dependence on pressure and vasoactive agents in arterial smooth muscle: A model. ACTA ACUST UNITED AC 2016; 146:79-96. [PMID: 26123196 PMCID: PMC4485026 DOI: 10.1085/jgp.201511380] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A mathematical model incorporating junctional and stretch-activated microdomains and 37 protein components describes the myogenic response in arterial smooth muscle cells. Arterial smooth muscle (SM) cells respond autonomously to changes in intravascular pressure, adjusting tension to maintain vessel diameter. The values of membrane potential (Vm) and sarcoplasmic Ca2+ concentration (Cain) within minutes of a change in pressure are the results of two opposing pathways, both of which use Ca2+ as a signal. This works because the two Ca2+-signaling pathways are confined to distinct microdomains in which the Ca2+ concentrations needed to activate key channels are transiently higher than Cain. A mathematical model of an isolated arterial SM cell is presented that incorporates the two types of microdomains. The first type consists of junctions between cisternae of the peripheral sarcoplasmic reticulum (SR), containing ryanodine receptors (RyRs), and the sarcolemma, containing voltage- and Ca2+-activated K+ (BK) channels. These junctional microdomains promote hyperpolarization, reduced Cain, and relaxation. The second type is postulated to form around stretch-activated nonspecific cation channels and neighboring Ca2+-activated Cl− channels, and promotes the opposite (depolarization, increased Cain, and contraction). The model includes three additional compartments: the sarcoplasm, the central SR lumen, and the peripheral SR lumen. It incorporates 37 protein components. In addition to pressure, the model accommodates inputs of α- and β-adrenergic agonists, ATP, 11,12-epoxyeicosatrienoic acid, and nitric oxide (NO). The parameters of the equations were adjusted to obtain a close fit to reported Vm and Cain as functions of pressure, which have been determined in cerebral arteries. The simulations were insensitive to ±10% changes in most of the parameters. The model also simulated the effects of inhibiting RyR, BK, or voltage-activated Ca2+ channels on Vm and Cain. Deletion of BK β1 subunits is known to increase arterial–SM tension. In the model, deletion of β1 raised Cain at all pressures, and these increases were reversed by NO.
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Affiliation(s)
- Arthur Karlin
- Department of Biochemistry and Molecular Biophysics, Department of Physiology and Cellular Biophysics, and Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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28
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Geng FH, Li GH, Zhang X, Zhang P, Dong MQ, Zhao ZJ, Zhang Y, Dong L, Gao F. Berberine improves mesenteric artery insulin sensitivity through up-regulating insulin receptor-mediated signalling in diabetic rats. Br J Pharmacol 2016. [PMID: 26914282 DOI: 10.1111/bph.2015.172.issue-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Berberine, a small molecule derived from Coptidis rhizome, has been found to be potent at lowering blood glucose and regulating lipid metabolism. Recent clinical studies have shown that berberine reduces blood pressure and increases systemic insulin sensitivity in patients with metabolic syndrome; however, the underlying mechanism is still unclear. Here, we investigated the mechanism by which berberine improves vascular insulin sensitivity in diabetic rats. EXPERIMENTAL APPROACH Diabetes was induced in male Sprague–Dawley rats by feeding a high-fat diet and administration of a low dose of streptozotocin. These diabetic rats were treated with berberine (200 mg·kg(−1)·day(−1), gavage) for 4 weeks. Vascular dilation was determined in isolated mesenteric artery rings. Effects of berberine on insulin signalling were also studied in human artery endothelial cells cultured in high glucose (25 mmol·L(−1)) and palmitate (500 μmol·L(−1)). KEY RESULTS Berberine treatment for 4 weeks significantly restored the impaired ACh- and insulin-induced vasodilatation of mesenteric arteries from diabetic rats. In isolated mesenteric artery rings, berberine (2.5–10 μmol·L(−1)) elicited dose-dependent vasodilatation and significantly enhanced insulin-induced vasodilatation. Mechanistically, berberine up-regulated phosphorylation of the insulin receptor and its downstream signalling molecules AMPK, Akt and eNOS, and increased cell viability and autophagy in cultured endothelial cells. Moreover, down-regulating insulin receptors with specific siRNA significantly attenuated berberine-induced phosphorylation of AMPK. CONCLUSIONS AND IMPLICATIONS Berberine improves diabetic vascular insulin sensitivity and mesenteric vasodilatation by up-regulating insulin receptor-mediated signalling in diabetic rats. These findings suggest berberine has potential as a preventive or adjunctive treatment of diabetic vascular complications. LINKED ARTICLES This article is part of a themed section on Chinese Innovation in Cardiovascular Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-23.
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Affiliation(s)
- Feng-Hao Geng
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Guo-Hua Li
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Xing Zhang
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Peng Zhang
- Department of Orthopedic Surgery, Urumqi General Hospital, Urumqi, China
| | - Ming-Qing Dong
- Department of Pathophysiology, The Fourth Military Medical University, Xi'an, China
| | - Zhi-Jing Zhao
- Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yuan Zhang
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Ling Dong
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China
| | - Feng Gao
- School of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China.,Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
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29
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Chen YF, Wang C, Zhang R, Wang H, Ma R, Jin S, Xiang JZ, Tang Q. Tacrolimus inhibits vasoconstriction by increasing Ca(2+) sparks in rat aorta. ACTA ACUST UNITED AC 2016; 36:8-13. [PMID: 26838733 DOI: 10.1007/s11596-016-1534-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 12/29/2015] [Indexed: 11/26/2022]
Abstract
The present study attempted to test a novel hypothesis that Ca(2+) sparks play an important role in arterial relaxation induced by tacrolimus. Recorded with confocal laser scanning microscopy, tacrolimus (10 µmol/L) increased the frequency of Ca(2+) sparks, which could be reversed by ryanodine (10 µmol/L). Electrophysiological experiments revealed that tacrolimus (10 µmol/L) increased the large-conductance Ca(2+)-activated K(+) currents (BKCa) in rat aortic vascular smooth muscle cells (AVSMCs), which could be blocked by ryanodine (10 µmol/L). Furthermore, tacrolimus (10 and 50 µmol/L) reduced the contractile force induced by norepinephrine (NE) or KCl in aortic vascular smooth muscle in a concentration-dependent manner, which could be also significantly attenuated by iberiotoxin (100 nmol/L) and ryanodine (10 µmol/L) respectively. In conclusion, tacrolimus could indirectly activate BKCa currents by increasing Ca(2+) sparks released from ryanodine receptors, which inhibited the NE- or KCl-induced contraction in rat aorta.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/metabolism
- Aorta/physiology
- Calcium Signaling
- Cells, Cultured
- Large-Conductance Calcium-Activated Potassium Channels/metabolism
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Norepinephrine/pharmacology
- Rats
- Rats, Sprague-Dawley
- Ryanodine/pharmacology
- Tacrolimus/pharmacology
- Vasoconstriction
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Affiliation(s)
- Yu-Fang Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Chen Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Rui Zhang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Huan Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Rong Ma
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Si Jin
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ji-Zhou Xiang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qiang Tang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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30
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Nieves-Cintrón M, Nystoriak MA, Prada MP, Johnson K, Fayer W, Dell'Acqua ML, Scott JD, Navedo MF. Selective down-regulation of KV2.1 function contributes to enhanced arterial tone during diabetes. J Biol Chem 2015; 290:7918-29. [PMID: 25670860 DOI: 10.1074/jbc.m114.622811] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enhanced arterial tone is a leading cause of vascular complications during diabetes. Voltage-gated K(+) (KV) channels are key regulators of vascular smooth muscle cells (VSMCs) contractility and arterial tone. Whether impaired KV channel function contributes to enhance arterial tone during diabetes is unclear. Here, we demonstrate a reduction in KV-mediated currents (IKv) in VSMCs from a high fat diet (HFD) mouse model of type 2 diabetes. In particular, IKv sensitive to stromatoxin (ScTx), a potent KV2 blocker, were selectively reduced in diabetic VSMCs. This was associated with decreased KV2-mediated regulation of arterial tone and suppression of the KV2.1 subunit mRNA and protein in VSMCs/arteries isolated from HFD mice. We identified protein kinase A anchoring protein 150 (AKAP150), via targeting of the phosphatase calcineurin (CaN), and the transcription factor nuclear factor of activated T-cells c3 (NFATc3) as required determinants of KV2.1 suppression during diabetes. Interestingly, substantial reduction in transcript levels for KV2.1 preceded down-regulation of large conductance Ca(2+)-activated K(+) (BKCa) channel β1 subunits, which are ultimately suppressed in chronic hyperglycemia to a similar extent. Together, our study supports the concept that transcriptional suppression of KV2.1 by activation of the AKAP150-CaN/NFATc3 signaling axis contributes to enhanced arterial tone during diabetes.
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Affiliation(s)
| | - Matthew A Nystoriak
- From the Department of Pharmacology, University of California, Davis, California 95616
| | - Maria Paz Prada
- From the Department of Pharmacology, University of California, Davis, California 95616
| | - Kenneth Johnson
- From the Department of Pharmacology, University of California, Davis, California 95616
| | - William Fayer
- From the Department of Pharmacology, University of California, Davis, California 95616
| | - Mark L Dell'Acqua
- the Department of Pharmacology, University of Colorado, Denver, Colorado 80045, and
| | - John D Scott
- the Howard Hughes Medical Institute and Department of Pharmacology, University of Washington, Seattle, Washington 98195
| | - Manuel F Navedo
- From the Department of Pharmacology, University of California, Davis, California 95616,
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31
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Fernández-Velasco M, Ruiz-Hurtado G, Gómez AM, Rueda A. Ca(2+) handling alterations and vascular dysfunction in diabetes. Cell Calcium 2014; 56:397-407. [PMID: 25218935 DOI: 10.1016/j.ceca.2014.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/30/2014] [Accepted: 08/07/2014] [Indexed: 12/12/2022]
Abstract
More than 65% of patients with diabetes mellitus die from cardiovascular disease or stroke. Hyperglycemia, due to either reduced insulin secretion or reduced insulin sensitivity, is the hallmark feature of diabetes mellitus. Vascular dysfunction is a distinctive phenotype found in both types of diabetes and could be responsible for the high incidence of stroke, heart attack, and organ damage in diabetic patients. In addition to well-documented endothelial dysfunction, Ca(2+) handling alterations in vascular smooth muscle cells (VSMCs) play a key role in the development and progression of vascular complications in diabetes. VSMCs provide not only structural integrity to the vessels but also control myogenic arterial tone and systemic blood pressure through global and local Ca(2+) signaling. The Ca(2+) signalosome of VSMCs is integrated by an extensive number of Ca(2+) handling proteins (i.e. channels, pumps, exchangers) and related signal transduction components, whose function is modulated by endothelial effectors. This review summarizes recent findings concerning alterations in endothelium and VSMC Ca(2+) signaling proteins that may contribute to the vascular dysfunction found in the diabetic condition.
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Affiliation(s)
| | - Gema Ruiz-Hurtado
- Unidad de Hipertensión, Instituto de Investigación imas12, Hospital 12 de Octubre, Madrid, Spain; Instituto Pluridisciplinar, Facultad de Farmacia, Universidad Complutense de Madrid, Spain
| | - Ana M Gómez
- Inserm, UMR S769, Faculté de Pharmacie, Université Paris Sud, Labex LERMIT, DHU TORINO, Châtenay-Malabry, France
| | - Angélica Rueda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, México City, Mexico.
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32
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The diabetic vasculature: physiological mechanisms of dysfunction and influence of aerobic exercise training in animal models. Life Sci 2014; 102:1-9. [PMID: 24583313 DOI: 10.1016/j.lfs.2014.02.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 01/30/2014] [Accepted: 02/15/2014] [Indexed: 02/08/2023]
Abstract
Diabetes mellitus (DM) is associated with a number of complications of which chronic vascular complications are undoubtedly the most complex and significant consequence. With a significant impact on health care, 50-80% of people with diabetes die of cardiovascular disease (including coronary artery disease, stroke, peripheral vascular disease and other vascular disease), making it the major cause of morbidity and mortality in diabetic patients. A healthy lifestyle is essential in the management of DM, especially the inclusion of aerobic exercise, which has been shown effective in reducing the deleterious effects in vasculature. Interest in exercise studies has increased significantly with promising results that demonstrate a future for investigation. Considering the importance of this emerging field, the aim of this mini-review is to summarize and integrate animal studies investigating physiological mechanisms of vascular dysfunction and remodeling in type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) and how these are influenced by chronic aerobic exercise training.
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33
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Pabbidi MR, Mazur O, Fan F, Farley JM, Gebremedhin D, Harder DR, Roman RJ. Enhanced large conductance K+ channel activity contributes to the impaired myogenic response in the cerebral vasculature of Fawn Hooded Hypertensive rats. Am J Physiol Heart Circ Physiol 2014; 306:H989-H1000. [PMID: 24464756 DOI: 10.1152/ajpheart.00636.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Recent studies have indicated that the myogenic response (MR) in cerebral arteries is impaired in Fawn Hooded Hypertensive (FHH) rats and that transfer of a 2.4 megabase pair region of chromosome 1 (RNO1) containing 15 genes from the Brown Norway rat into the FHH genetic background restores MR in a FHH.1(BN) congenic strain. However, the mechanisms involved remain to be determined. The present study examined the role of the large conductance calcium-activated potassium (BK) channel in impairing the MR in FHH rats. Whole-cell patch-clamp studies of cerebral vascular smooth muscle cells (VSMCs) revealed that iberiotoxin (IBTX; BK inhibitor)-sensitive outward potassium (K+) channel current densities are four- to fivefold greater in FHH than in FHH.1(BN) congenic strain. Inside-out patches indicated that the BK channel open probability (NPo) is 10-fold higher and IBTX reduced NPo to a greater extent in VSMCs isolated from FHH than in FHH.1(BN) rats. Voltage sensitivity of the BK channel is enhanced in FHH as compared with FHH.1(BN) rats. The frequency and amplitude of spontaneous transient outward currents are significantly greater in VSMCs isolated from FHH than in FHH.1(BN) rats. However, the expression of the BK-α and -β-subunit proteins in cerebral vessels as determined by Western blot is similar between the two groups. Middle cerebral arteries (MCAs) isolated from FHH rats exhibited an impaired MR, and administration of IBTX restored this response. These results indicate that there is a gene on RNO1 that impairs MR in the MCAs of FHH rats by enhancing BK channel activity.
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Affiliation(s)
- Mallikarjuna R Pabbidi
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
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34
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Contreras GF, Castillo K, Enrique N, Carrasquel-Ursulaez W, Castillo JP, Milesi V, Neely A, Alvarez O, Ferreira G, González C, Latorre R. A BK (Slo1) channel journey from molecule to physiology. Channels (Austin) 2013; 7:442-58. [PMID: 24025517 DOI: 10.4161/chan.26242] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Calcium and voltage-activated potassium (BK) channels are key actors in cell physiology, both in neuronal and non-neuronal cells and tissues. Through negative feedback between intracellular Ca (2+) and membrane voltage, BK channels provide a damping mechanism for excitatory signals. Molecular modulation of these channels by alternative splicing, auxiliary subunits and post-translational modifications showed that these channels are subjected to many mechanisms that add diversity to the BK channel α subunit gene. This complexity of interactions modulates BK channel gating, modifying the energetic barrier of voltage sensor domain activation and channel opening. Regions for voltage as well as Ca (2+) sensitivity have been identified, and the crystal structure generated by the 2 RCK domains contained in the C-terminal of the channel has been described. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, has been found to be relevant in many physiological processes. This review includes the hallmarks of BK channel biophysics and its physiological impact on specific cells and tissues, highlighting its relationship with auxiliary subunit expression.
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Affiliation(s)
- Gustavo F Contreras
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile; Doctorado en Ciencias mención Neurociencia; Universidad de Valparaíso; Valparaíso, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
| | - Nicolás Enrique
- Grupo de Investigación en Fisiología Vascular (GINFIV); Universidad Nacional de la Plata; La Plata, Argentina
| | - Willy Carrasquel-Ursulaez
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile; Doctorado en Ciencias mención Neurociencia; Universidad de Valparaíso; Valparaíso, Chile
| | - Juan Pablo Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile; Facultad de Ciencias; Universidad de Chile; Santiago, Chile
| | - Verónica Milesi
- Grupo de Investigación en Fisiología Vascular (GINFIV); Universidad Nacional de la Plata; La Plata, Argentina
| | - Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
| | | | - Gonzalo Ferreira
- Laboratorio de Canales Iónicos; Departamento de Biofísica; Facultad de Medicina; Universidad de la República; Montevideo, Uruguay
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
| | - Ramón Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
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Abstract
Despite recent advances in our understanding of the molecular and cellular mechanisms behind vascular conducted responses (VCRs) in systemic arterioles, we still know very little about their potential physiological and pathophysiological role in brain penetrating arterioles controlling blood flow to the deeper areas of the brain. The scope of the present review is to present an overview of the conceptual, mechanistic, and physiological role of VCRs in resistance vessels, and to discuss in detail the recent advances in our knowledge of VCRs in brain arterioles controlling cerebral blood flow. We provide a schematic view of the ion channels and intercellular communication pathways necessary for conduction of an electrical and mechanical response in the arteriolar wall, and discuss the local signaling mechanisms and cellular pathway involved in the responses to different local stimuli and in different vascular beds. Physiological modulation of VCRs, which is a rather new finding in this field, is discussed in the light of changes in plasma membrane ion channel conductance as a function of health status or disease. Finally, we discuss the possible role of VCRs in cerebrovascular function and disease as well as suggest future directions for studying VCRs in the cerebral circulation.
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Chung WS, Weissman JL, Farley J, Drummond HA. βENaC is required for whole cell mechanically gated currents in renal vascular smooth muscle cells. Am J Physiol Renal Physiol 2013; 304:F1428-37. [PMID: 23552864 DOI: 10.1152/ajprenal.00444.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Myogenic constrictor responses in small renal arteries and afferent arterioles are suppressed in mice with reduced levels of β-epithelial Na⁺ channel (βENaC(m/m)). The underlying mechanism is unclear. Decreased activity of voltage-gated calcium channels (VGCC) or mechanically gated ion channels and increased activity of large conductance calcium-activated potassium (BK) channels are a few possible mechanisms. The purpose of this study was to determine if VGCC, BK, or mechanically gated ion channel activity was altered in renal vascular smooth muscle cell (VSMC) from βENaC(m/m) mice. To address this, we used whole cell patch-clamp electrophysiological approaches in freshly isolated renal VSMCs. Compared with βENaC(+/+) controls, the current-voltage relationships for VGCC and BK activity are similar in βENaC(m/m) mice. These findings suggest neither VGCC nor BK channel dysfunction accounts for reduced myogenic constriction in βENaC(m/m) mice. We then examined mechanically gated currents using a novel in vitro assay where VSMCs are mechanically activated by stretching an underlying elastomer. We found the mechanically gated currents, predominantly carried by Na⁺, are observed with less frequency (87 vs. 43%) and have smaller magnitude (-54.1 ± 12.5 vs. -20.9 ± 4.9 pA) in renal VSMCs from βENaC(m/m) mice. Residual currents are expected in this model since VSMC βENaC expression is reduced by 50%. These findings suggest βENaC is required for normal mechanically gated currents in renal VSMCs and their disruption may account for the reduced myogenic constriction in the βENaC(m/m) model. Our findings are consistent with the role of βENaC as a VSMC mechanosensor and function of evolutionarily related nematode degenerin proteins.
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Affiliation(s)
- Wen-Shuo Chung
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA
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37
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Zheng YM, Park SW, Stokes L, Tang Q, Xiao JH, Wang YX. Distinct activity of BK channel β1-subunit in cerebral and pulmonary artery smooth muscle cells. Am J Physiol Cell Physiol 2013; 304:C780-9. [PMID: 23426969 DOI: 10.1152/ajpcell.00006.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This study was designed to test a hypothesis that the functional activity of big-conductance, Ca(2+)-activated K(+) (BK) channels is different in cerebral and pulmonary artery smooth muscle cells (CASMCs and PASMCs). Using patch-clamp recordings, we found that the activity of whole cell and single BK channels were significantly higher in CASMCs than in PASMCs. The voltage and Ca(2+) sensitivity of BK channels were greater in CASMCs than in PASMCs. Targeted gene knockout of β(1)-subunits significantly reduced BK currents in CASMCs but had no effect in PASMCs. Western blotting experiments revealed that BK channel α-subunit protein expression level was comparable in CASMCs and PASMCs; however, β(1)-subunit protein expression level was higher in CASMCs than in PASMCs. Inhibition of BK channels by the specific blocker iberiotoxin enhanced norepinephrine-induced increase in intracellular calcium concentration in CASMCs but not in PASMCs. Systemic artery blood pressure was elevated in β(1)(-/-) mice. In contrast, pulmonary artery blood pressure was normal in β(1)(-/-) mice. These findings provide the first evidence that the activity of BK channels is higher in cerebral than in PASMCs. This heterogeneity is primarily determined by the differential β(1)-subunit function and contributes to diverse cellular responses in these two distinct types of cells.
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Affiliation(s)
- Yun-Min Zheng
- Center for Cardiovascular Sciences, Albany Medical College, 47 New Scotland Ave., Albany, NY 12208, USA.
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38
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Wan E, Kushner JS, Zakharov S, Nui XW, Chudasama N, Kelly C, Waase M, Doshi D, Liu G, Iwata S, Shiomi T, Katchman A, D'Armiento J, Homma S, Marx SO. Reduced vascular smooth muscle BK channel current underlies heart failure-induced vasoconstriction in mice. FASEB J 2013; 27:1859-67. [PMID: 23325318 DOI: 10.1096/fj.12-223511] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Excessively increased peripheral vasoconstriction is a hallmark of heart failure (HF). Here, we show that in mice with systolic HF post-myocardial infarction, the myogenic tone of third-order mesenteric resistance vessels is increased, the vascular smooth muscle (VSM) membrane potential is depolarized by ~20 mV, and vessel wall intracellular [Ca(2+)] is elevated relative to that in sham-operated control mice. Despite the increased [Ca(2+)], the frequency and amplitude of spontaneous transient outward currents (STOCs), mediated by large conductance, Ca(2+)-activated BK channels, were reduced by nearly 80% (P<0.01) and 25% (P<0.05), respectively, in HF. The expression of the BK α and β1 subunits was reduced in HF mice compared to controls (65 and 82% lower, respectively, P<0.01). Consistent with the importance of a reduction in BK channel expression and function in mediating the HF-induced increase in myogenic tone are two further findings: a blunting of paxilline-induced increase in myogenic tone in HF mice compared to controls (0.9 vs. 10.9%, respectively), and that HF does not alter the increased myogenic tone of BK β1-null mice. These findings identify electrical dysregulation within VSM, specifically the reduction of BK currents, as a key molecular mechanism sensitizing resistance vessels to pressure-induced vasoconstriction in systolic HF.
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Affiliation(s)
- Elaine Wan
- Division of Cardiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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Rueda A, Fernández-Velasco M, Benitah JP, Gómez AM. Abnormal Ca2+ spark/STOC coupling in cerebral artery smooth muscle cells of obese type 2 diabetic mice. PLoS One 2013; 8:e53321. [PMID: 23301060 PMCID: PMC3536748 DOI: 10.1371/journal.pone.0053321] [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] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 11/30/2012] [Indexed: 01/19/2023] Open
Abstract
Diabetes is a major risk factor for stroke. However, the molecular mechanisms involved in cerebral artery dysfunction found in the diabetic patients are not completely elucidated. In cerebral artery smooth muscle cells (CASMCs), spontaneous and local increases of intracellular Ca2+ due to the opening of ryanodine receptors (Ca2+ sparks) activate large conductance Ca2+-activated K+ (BK) channels that generate spontaneous transient outward currents (STOCs). STOCs have a key participation in the control of vascular myogenic tone and blood pressure. Our goal was to investigate whether alterations in Ca(2+) spark and STOC activities, measured by confocal microscopy and patch-clamp technique, respectively, occur in isolated CASMCs of an experimental model of type-2 diabetes (db/db mouse). We found that mean Ca(2+) spark amplitude, duration, size and rate-of-rise were significantly smaller in Fluo-3 loaded db/db compared to control CASMCs, with a subsequent decrease in the total amount of Ca(2+) released through Ca(2+) sparks in db/db CASMCs, though Ca(2+) spark frequency remained. Interestingly, the frequency of large-amplitude Ca(2+) sparks was also significantly reduced in db/db cells. In addition, the frequency and amplitude of STOCs were markedly reduced at all voltages tested (from -50 to 0 mV) in db/db CASMCs. The latter correlates with decreased BK channel β1/α subunit ratio found in db/db vascular tissues. Taken together, Ca(2+) spark alterations lead to inappropriate BK channels activation in CASMCs of db/db mice and this condition is aggravated by the decrease in the BK β1 subunit/α subunit ratio which underlies the significant reduction of Ca(2+) spark/STOC coupling in CASMCs of diabetic animals.
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Affiliation(s)
- Angélica Rueda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, México City, México
- Inserm, U-637; Université de Montpellier 1, Université de Montpellier 2, Montpellier, France
- * E-mail: (AMG); (AR)
| | - María Fernández-Velasco
- Inserm, U-637; Université de Montpellier 1, Université de Montpellier 2, Montpellier, France
- Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
| | - Jean-Pierre Benitah
- Inserm, U769; Université de Paris-Sud, IFR141, Labex Lermit, Châtenay-Malabry, France
| | - Ana María Gómez
- Inserm, U769; Université de Paris-Sud, IFR141, Labex Lermit, Châtenay-Malabry, France
- * E-mail: (AMG); (AR)
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40
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Delbin MA, Davel APC, Couto GK, de Araújo GG, Rossoni LV, Antunes E, Zanesco A. Interaction between advanced glycation end products formation and vascular responses in femoral and coronary arteries from exercised diabetic rats. PLoS One 2012; 7:e53318. [PMID: 23285277 PMCID: PMC3532341 DOI: 10.1371/journal.pone.0053318] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 11/29/2012] [Indexed: 01/28/2023] Open
Abstract
Background The majority of studies have investigated the effect of exercise training (TR) on vascular responses in diabetic animals (DB), but none evaluated nitric oxide (NO) and advanced glycation end products (AGEs) formation associated with oxidant and antioxidant activities in femoral and coronary arteries from trained diabetic rats. Our hypothesis was that 8-week TR would alter AGEs levels in type 1 diabetic rats ameliorating vascular responsiveness. Methodology/Principal Findings Male Wistar rats were divided into control sedentary (C/SD), sedentary diabetic (SD/DB), and trained diabetic (TR/DB). DB was induced by streptozotocin (i.p.: 60 mg/kg). TR was performed for 60 min per day, 5 days/week, during 8 weeks. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), phenylephrine (PHE) and tromboxane analog (U46619) were obtained. The protein expressions of eNOS, receptor for AGEs (RAGE), Cu/Zn-SOD and Mn-SOD were analyzed. Tissues NO production and reactive oxygen species (ROS) generation were evaluated. Plasma nitrate/nitrite (NOx−), superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS) and Nε-(carboxymethyl) lysine (CML, AGE biomarker). A rightward shift in the concentration-response curves to ACh was observed in femoral and coronary arteries from SD/DB that was accompanied by an increase in TBARS and CML levels. Decreased in the eNOS expression, tissues NO production and NOx− levels were associated with increased ROS generation. A positive interaction between the beneficial effect of TR on the relaxing responses to ACh and the reduction in TBARS and CML levels were observed without changing in antioxidant activities. The eNOS protein expression, tissues NO production and ROS generation were fully re-established in TR/DB, but plasma NOx− levels were partially restored. Conclusion Shear stress induced by TR fully restores the eNOS/NO pathway in both preparations from non-treated diabetic rats, however, a massive production of AGEs still affecting relaxing responses possibly involving other endothelium-dependent vasodilator agents, mainly in coronary artery.
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MESH Headings
- Animals
- Antioxidants/metabolism
- Antioxidants/pharmacology
- Coronary Vessels/drug effects
- Coronary Vessels/metabolism
- Coronary Vessels/physiopathology
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Experimental/therapy
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/physiopathology
- Endothelium-Dependent Relaxing Factors/metabolism
- Endothelium-Dependent Relaxing Factors/pharmacology
- Femoral Artery/drug effects
- Femoral Artery/metabolism
- Femoral Artery/physiopathology
- Glycation End Products, Advanced/metabolism
- Glycation End Products, Advanced/pharmacology
- Male
- Physical Conditioning, Animal
- Rats
- Rats, Wistar
- Reactive Oxygen Species/metabolism
- Reactive Oxygen Species/pharmacology
- Streptozocin
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Affiliation(s)
- Maria A. Delbin
- Department of Physical Education, Institute of Bioscience, University of São Paulo State (UNESP), Rio Claro, São Paulo, Brazil
| | - Ana Paula C. Davel
- Department of Anatomy, Cellular Biology, Physiology and Biophysics, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Gisele Kruger Couto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, São Paulo, Brazil
| | - Gustavo G. de Araújo
- Department of Physical Education, Institute of Bioscience, University of São Paulo State (UNESP), Rio Claro, São Paulo, Brazil
| | - Luciana Venturini Rossoni
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, São Paulo, Brazil
| | - Edson Antunes
- Department of Pharmacology, Faculty of Medical Sciences, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Angelina Zanesco
- Department of Physical Education, Institute of Bioscience, University of São Paulo State (UNESP), Rio Claro, São Paulo, Brazil
- * E-mail:
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41
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Marrachelli VG, Centeno JM, Miranda I, Castelló-Ruiz M, Burguete MC, Jover-Mengual T, Salom JB, Torregrosa G, Miranda FJ, Alborch E. Diabetes impairs the atrial natriuretic peptide relaxant action mediated by potassium channels and prostacyclin in the rabbit renal artery. Pharmacol Res 2012; 66:392-400. [DOI: 10.1016/j.phrs.2012.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 07/23/2012] [Accepted: 07/30/2012] [Indexed: 01/11/2023]
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42
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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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43
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Vetri F, Xu H, Paisansathan C, Pelligrino DA. Impairment of neurovascular coupling in type 1 diabetes mellitus in rats is linked to PKC modulation of BK(Ca) and Kir channels. Am J Physiol Heart Circ Physiol 2012; 302:H1274-84. [PMID: 22268114 DOI: 10.1152/ajpheart.01067.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We hypothesized that chronic hyperglycemia has a detrimental effect on neurovascular coupling in the brain and that this may be linked to protein kinase C (PKC)-mediated phosphorylation. Therefore, in a rat model of streptozotocin-induced chronic type 1 diabetes mellitus (T1DM), and in nondiabetic (ND) controls, we monitored pial arteriole diameter changes during sciatic nerve stimulation and topical applications of the large-conductance Ca(2+)-operated K(+) channel (BK(Ca)) opener, NS-1619, or the K(+) inward rectifier (Kir) channel agonist, K(+). In the T1DM vs. ND rats, the dilatory response associated with sciatic nerve stimulation was decreased by ∼30%, whereas pial arteriolar dilations to NS-1619 and K(+) were largely suppressed. These responses were completely restored by the acute topical application of a PKC antagonist, calphostin C. Moreover, the suffusion of a PKC activator, phorbol 12,13-dibutyrate, in ND rats was able to reproduce the vascular reactivity impairments found in T1DM rats. Assay of PKC activity in brain samples from T1DM vs. ND rats revealed a significant gain in activity only in specimens harvested from the pial and superficial glia limitans tissue, but not in bulk cortical gray matter. Altogether, these findings suggest that the T1DM-associated impairment of neurovascular coupling may be mechanistically linked to a readily reversible PKC-mediated depression of BK(Ca) and Kir channel activity.
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Affiliation(s)
- Francesco Vetri
- Neuroanesthesia Research Laboratory, Department of Anesthesiology, University of Illinois at Chicago, 60612, USA.
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44
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Mori A, Suzuki S, Sakamoto K, Nakahara T, Ishii K. Vasodilation of retinal arterioles induced by activation of BKCa channels is attenuated in diabetic rats. Eur J Pharmacol 2011; 669:94-9. [PMID: 21871885 DOI: 10.1016/j.ejphar.2011.07.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 07/15/2011] [Accepted: 07/29/2011] [Indexed: 02/01/2023]
Abstract
The large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels modulate the retinal vascular tone, but question of whether the impairment of the channel function contributes to abnormalities of retinal circulation has not yet been completely elucidated. The purpose of this study was to examine effects of diabetes on the vasodilation induced by activation of BK(Ca) channels. Male Wistar rats were treated with streptozotocin and experiments were performed 2 weeks later. The streptozotocin-treated animals were given drinking water containing 5% d-glucose to shorten the term in the development of retinal vascular dysfunction. The retinal vascular responses were assessed by measuring diameter of retinal arterioles in the fundus images that were captured with an original fundus camera system. In non-diabetic rats, vasodilator effects of acetylcholine on retinal arterioles were significantly reduced by iberiotoxin, an inhibitor of BK(Ca) channels. However, the inhibitory effect of iberiotoxin was not observed in diabetic rats, and the responses to the BK(Ca) channel opener BMS-191011 were almost completely abolished. The retinal vasodilator response to acetylcholine, possibly an endothelium-derived hyperpolarizing factor-mediated response, observed after treatment with N(G)-nitro-l-arginine methyl ester and indomethacin was markedly reduced in diabetic rats. The responses to pinacidil, an opener of ATP-sensitive K(+) channels, were unchanged. These results suggest that the retinal vasodilator response mediated through mechanisms involving activation of BK(Ca) channels is diminished at the early stage of diabetes in rats. The impairment of BK(Ca) channel function may contribute to abnormal retinal hemodynamics in diabetes and consequently play an important role in the pathogenesis of diabetic retinopathy.
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Affiliation(s)
- Asami Mori
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
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45
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Abstract
CONTEXT Recent prospective clinical trials have failed to confirm a unique benefit from normalization of glycemia on cardiovascular disease outcomes, despite evidence from basic vascular biology, epidemiological, and cohort studies. EVIDENCE ACQUISITION The literature was searched using the http://www.ncbi.nlm.nih.gov search engine including over 20 million citations on MEDLINE (1970 to present). Keyword searches included: atherosclerosis, cardiovascular, and glucose. Epidemiological, cohort, and interventional data on cardiovascular disease outcomes and glycemic control were reviewed along with analysis of recent reviews on this topic. EVIDENCE SYNTHESIS High glucose activates a proatherogenic phenotype in all cell types in the vessel wall including endothelial cells, vascular smooth muscle cells, inflammatory cells, fibroblasts, and platelets, leading to a feedforward atherogenic response. EPIDEMIOLOGICAL AND COHORT STUDIES: Epidemiological and cohort evidence indicates a clear and consistent correlation of glycemia with cardiovascular disease. A recent report of over 25,000 subjects with diabetes in the Swedish National Diabetes Registry verifies this relationship in contemporary practice. Interventional Studies: Prospective randomized interventions targeting a hemoglobin A1c of 6-6.5% for cardiovascular disease prevention failed to consistently decrease cardiovascular events or all-cause mortality. CONCLUSIONS Basic vascular biology data plus epidemiological and cohort evidence would predict that glucose control should impact cardiovascular events. Prospective clinical trials demonstrate that current strategies that improve blood glucose do not achieve this goal but suggest that a period of optimal control may confer long-term cardiovascular disease benefit. Clinicians should target a hemoglobin A1c of 7% for the prevention of microvascular complications, individualized to avoid hypoglycemia.
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Affiliation(s)
- Jane E B Reusch
- Denver VA Medical Center, Clermont Street, Denver, Colorado 80220, USA.
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46
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Chang H, Ma YG, Wang YY, Song Z, Li Q, Yang N, Zhao HZ, Feng HZ, Chang YM, Ma J, Yu ZB, Xie MJ. High glucose alters apoptosis and proliferation in HEK293 cells by inhibition of cloned BK Ca channel. J Cell Physiol 2011; 226:1660-75. [PMID: 21413024 DOI: 10.1002/jcp.22497] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It has been reported that diabetic vascular dysfunction is associated with impaired function of large conductance Ca(2+) -activated K(+) (BK(Ca) ) channels. However, it is unclear whether impaired BK(Ca) channel directly participates in regulating diabetic vascular remodeling by altering cell growth in response to hyperglycemia. In the present study, we investigated the specific role of BK(Ca) channel in controlling apoptosis and proliferation under high glucose concentration (25 mM). The cDNA encoding the α+β1 subunit of BK(Ca) channel, hSloα+β1, was transiently transfected into human embryonic kidney 293 (HEK293) cells. Cloned BK(Ca) currents were recorded by both whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry and analysis of fragmented DNA by agarose gel electrophoresis. Cell proliferation was investigated by flow cytometry assays, MTT test, and immunocytochemistry. In addition, the expression of anti-apoptotic protein Bcl-2, intracellular Ca(2+) , and mitochondrial membrane potential (Δψm) were also examined to investigate the possible mechanisms. Our results indicate that inhibition of cloned BK(Ca) channels might be responsible for hyperglycemia-altered apoptosis and proliferation in HEK-hSloα+β1 cells. However, activation of BK(Ca) channel by NS1619 or Tamoxifen significantly induced apoptosis and suppressed proliferation in HEK-hSloα+β1 cells under hyperglycemia condition. When rat cerebral smooth muscle cells were cultured in hyperglycemia, similar findings were observed. Moreover, the possible mechanisms underlying the activation of BK(Ca) channel were associated with decreased expression of Bcl-2, elevation of intracellular Ca(2+) , and a concomitant depolarization of Δψm in HEK-hSloα+β1 cells. In conclusion, cloned BK(Ca) channel directly regulated apoptosis and proliferation of HEK293 cell under hyperglycemia condition.
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Affiliation(s)
- Hui Chang
- Department of Aerospace Physiology, Key Laboratory of Aerospace Medicine of Ministry of Education, Fourth Military Medical University, Xi'an, Shaanxi Province, China
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47
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Howitt L, Sandow SL, Grayson TH, Ellis ZE, Morris MJ, Murphy TV. Differential effects of diet-induced obesity on BKCa {beta}1-subunit expression and function in rat skeletal muscle arterioles and small cerebral arteries. Am J Physiol Heart Circ Physiol 2011; 301:H29-40. [PMID: 21536854 DOI: 10.1152/ajpheart.00134.2011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanisms underlying obesity-related vascular dysfunction are unclear. This study examined the effect of diet-induced obesity on expression and function of large conductance Ca(2+)-activated potassium channel (BK(Ca)) in rat pressurized small resistance vessels with myogenic tone. Male Sprague-Dawley rats fed a cafeteria-style high fat diet (HFD; ∼30% energy from fat) for 16-20 wk were ∼30% heavier than controls fed standard chow (∼13% fat). Obesity did not alter BK(Ca) α-subunit function or α-subunit protein or mRNA expression in vessels isolated from the cremaster muscle or middle-cerebral circulations. In contrast, BK(Ca) β(1)-subunit protein expression and function were significantly reduced in cremaster muscle arterioles but increased in middle-cerebral arteries from obese animals. Immunohistochemistry showed α- and β(1)-subunits were present exclusively in the smooth muscle of both vessels. Cremaster muscle arterioles from obese animals showed significantly increased medial thickness, and media-to-lumen ratio and pressurized arterioles showed increased myogenic tone at 30 mmHg, but not at 50-120 mmHg. Myogenic tone was not affected by obesity in middle-cerebral arteries. The BK(Ca) antagonist iberiotoxin constricted both cremaster muscle and middle-cerebral arterioles from control rats; this effect of iberiotoxin was abolished in cremaster muscle arteries only from obese rats. Diet-induced obesity has contrasting effects on BK(Ca) function in different vascular beds, through differential effects on β(1)-subunit expression. However, these alterations in BK(Ca) function had little effect on overall myogenic tone, suggesting that the mechanisms controlling myogenic tone can be altered and compensate for altered BK(Ca) expression and function.
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Affiliation(s)
- Lauren Howitt
- Dept. of Physiology, School of Medical Sciences, Univ. of New South Wales, Sydney, NSW 2052 Australia.
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Reduced Ca2+ spark activity after subarachnoid hemorrhage disables BK channel control of cerebral artery tone. J Cereb Blood Flow Metab 2011; 31:3-16. [PMID: 20736958 PMCID: PMC3049462 DOI: 10.1038/jcbfm.2010.143] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Intracellular Ca(2+) release events ('Ca(2+) sparks') and transient activation of large-conductance Ca(2+)-activated potassium (BK) channels represent an important vasodilator pathway in the cerebral vasculature. Considering the frequent occurrence of cerebral artery constriction after subarachnoid hemorrhage (SAH), our objective was to determine whether Ca(2+) spark and BK channel activity were reduced in cerebral artery myocytes from SAH model rabbits. Using laser scanning confocal microscopy, we observed ∼50% reduction in Ca(2+) spark activity, reflecting a decrease in the number of functional Ca(2+) spark discharge sites. Patch-clamp electrophysiology showed a similar reduction in Ca(2+) spark-induced transient BK currents, without change in BK channel density or single-channel properties. Consistent with a reduction in active Ca(2+) spark sites, quantitative real-time PCR and western blotting revealed decreased expression of ryanodine receptor type 2 (RyR-2) and increased expression of the RyR-2-stabilizing protein, FKBP12.6, in the cerebral arteries from SAH animals. Furthermore, inhibitors of Ca(2+) sparks (ryanodine) or BK channels (paxilline) constricted arteries from control, but not from SAH animals. This study shows that SAH-induced decreased subcellular Ca(2+) signaling events disable BK channel activity, leading to cerebral artery constriction. This phenomenon may contribute to decreased cerebral blood flow and poor outcome after aneurysmal SAH.
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Wu RS, Marx SO. The BK potassium channel in the vascular smooth muscle and kidney: α- and β-subunits. Kidney Int 2010; 78:963-74. [DOI: 10.1038/ki.2010.325] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sepehr-Ara L, Sepehr-Ara M, Mahmoudian M. Effect of the two new calcium channel blockers mebudipine and dibudipine in comparison to amlodipine on vascular flow of isolated kidney of diabetic rat. ACTA PHYSIOLOGICA HUNGARICA 2010; 97:281-9. [PMID: 20843766 DOI: 10.1556/aphysiol.97.2010.3.4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Calcium channel blockers are clinically useful vasodilators, used widely in the treatment of hypertension. These agents are reported to preserve or improve renal function in patients with essential hypertensive renal disease or diabetic renal disease. Among the classes of calcium channel blockers, dihydropyridine derivatives are widely used because of their potent vasodilating activity and weak cardiodepressant action. Mebudipine and dibudipine are two new 1,4-dihydropyridine calcium channel blockers that recently have been synthesized. In previous research mebudipine and dibudipine showed considerable relaxant effects on vascular and ileal smooth muscle cells. In this study we investigated the effects of these new drugs on vascular flow of isolated kidney of diabetic rat and compare their potencies to amlodipine. It is concluded that mebudipine and dibudipine (1-10 μM) are at least as potent as amlodipine in inhibiting PE-induced perfusion pressure in isolated kidney of diabetic rats. These new dihydropyridines improve kidney perfusion of diabetic rat in the setting of PE infusion. Similarly, amlodipine.
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Affiliation(s)
- L Sepehr-Ara
- Islamic Azad University, Kazeroon Branch, Department of Biology, Kazeroon, Iran.
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