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Shin S, Park J, Choi HY, Bu Y, Lee K. Blood-Pressure-Lowering and Endothelium-Dependent Vasorelaxant Effects of Nutgall Tree in Rats. Foods 2024; 13:1041. [PMID: 38611347 PMCID: PMC11011363 DOI: 10.3390/foods13071041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Hypertension is the crucial modifiable risk factor for cardiovascular diseases, and efforts to identify functional foods that are effective for hypertension control are increasing. The nutgall tree (NT, Rhus chinensis Mill.) is used in traditional medicine and food because of its medicinal value. However, the role of NT in hypertension has not been investigated. Therefore, the hypotensive effect of NT leaf ethanol extract (NTE) was investigated in spontaneously hypertensive rats (SHRs). SHRs were allocated to three groups (control, 300, or 1000 mg/kg NTE), and blood pressure was measured before and after oral administration. Systolic and diastolic blood pressure significantly decreased in the NTE 1000 mg/kg group and was the lowest at 2 h after administration (-26.4 ± 10.3, -33.5 ± 9.8%, respectively). Daily NTE administration for five days also resulted in a similar effect. Further, the vasorelaxant effects and related mechanisms were investigated in the aortas of Sprague Dawley rats. NTE showed the dose-dependent blood-vessel-relaxing effect, and its mechanism involves the NO-sGC-cGMP pathway, activation of K+ channels, and reduction in the vasoconstrictive action of angiotensin II. Therefore, our study provides basic data indicating the potential use of NTE as a functional food for high blood pressure.
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Affiliation(s)
- Sujin Shin
- Department of Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea;
| | - Junkyu Park
- Department of Science in Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea;
| | - Ho-Young Choi
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; (H.-Y.C.); (Y.B.)
| | - Youngmin Bu
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; (H.-Y.C.); (Y.B.)
| | - Kyungjin Lee
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; (H.-Y.C.); (Y.B.)
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2
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Baldwin SN, Jepps TA, Greenwood IA. Cycling matters: Sex hormone regulation of vascular potassium channels. Channels (Austin) 2023; 17:2217637. [PMID: 37243715 PMCID: PMC10228406 DOI: 10.1080/19336950.2023.2217637] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/07/2023] [Accepted: 05/19/2023] [Indexed: 05/29/2023] Open
Abstract
Sex hormones and the reproductive cycle (estrus in rodents and menstrual in humans) have a known impact on arterial function. In spite of this, sex hormones and the estrus/menstrual cycle are often neglected experimental factors in vascular basic preclinical scientific research. Recent research by our own laboratory indicates that cyclical changes in serum concentrations of sex -hormones across the rat estrus cycle, primary estradiol, have significant consequences for the subcellular trafficking and function of KV. Vascular potassium channels, including KV, are essential components of vascular reactivity. Our study represents a small part of a growing field of literature aimed at determining the role of sex hormones in regulating arterial ion channel function. This review covers key findings describing the current understanding of sex hormone regulation of vascular potassium channels, with a focus on KV channels. Further, we highlight areas of research where the estrus cycle should be considered in future studies to determine the consequences of physiological oscillations in concentrations of sex hormones on vascular potassium channel function.
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Affiliation(s)
- Samuel N Baldwin
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas A Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George’s University of London, London, UK
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3
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Davis MJ, Earley S, Li YS, Chien S. Vascular mechanotransduction. Physiol Rev 2023; 103:1247-1421. [PMID: 36603156 PMCID: PMC9942936 DOI: 10.1152/physrev.00053.2021] [Citation(s) in RCA: 50] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 09/26/2022] [Accepted: 10/04/2022] [Indexed: 01/07/2023] Open
Abstract
This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Scott Earley
- Department of Pharmacology, University of Nevada, Reno, Nevada
| | - Yi-Shuan Li
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
| | - Shu Chien
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
- Department of Medicine, University of California, San Diego, California
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4
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Jackson WF. Calcium-Dependent Ion Channels and the Regulation of Arteriolar Myogenic Tone. Front Physiol 2021; 12:770450. [PMID: 34819877 PMCID: PMC8607693 DOI: 10.3389/fphys.2021.770450] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/11/2021] [Indexed: 11/25/2022] Open
Abstract
Arterioles in the peripheral microcirculation regulate blood flow to and within tissues and organs, control capillary blood pressure and microvascular fluid exchange, govern peripheral vascular resistance, and contribute to the regulation of blood pressure. These important microvessels display pressure-dependent myogenic tone, the steady state level of contractile activity of vascular smooth muscle cells (VSMCs) that sets resting arteriolar internal diameter such that arterioles can both dilate and constrict to meet the blood flow and pressure needs of the tissues and organs that they perfuse. This perspective will focus on the Ca2+-dependent ion channels in the plasma and endoplasmic reticulum membranes of arteriolar VSMCs and endothelial cells (ECs) that regulate arteriolar tone. In VSMCs, Ca2+-dependent negative feedback regulation of myogenic tone is mediated by Ca2+-activated K+ (BKCa) channels and also Ca2+-dependent inactivation of voltage-gated Ca2+ channels (VGCC). Transient receptor potential subfamily M, member 4 channels (TRPM4); Ca2+-activated Cl− channels (CaCCs; TMEM16A/ANO1), Ca2+-dependent inhibition of voltage-gated K+ (KV) and ATP-sensitive K+ (KATP) channels; and Ca2+-induced-Ca2+ release through inositol 1,4,5-trisphosphate receptors (IP3Rs) participate in Ca2+-dependent positive-feedback regulation of myogenic tone. Calcium release from VSMC ryanodine receptors (RyRs) provide negative-feedback through Ca2+-spark-mediated control of BKCa channel activity, or positive-feedback regulation in cooperation with IP3Rs or CaCCs. In some arterioles, VSMC RyRs are silent. In ECs, transient receptor potential vanilloid subfamily, member 4 (TRPV4) channels produce Ca2+ sparklets that activate IP3Rs and intermediate and small conductance Ca2+ activated K+ (IKCa and sKCa) channels causing membrane hyperpolarization that is conducted to overlying VSMCs producing endothelium-dependent hyperpolarization and vasodilation. Endothelial IP3Rs produce Ca2+ pulsars, Ca2+ wavelets, Ca2+ waves and increased global Ca2+ levels activating EC sKCa and IKCa channels and causing Ca2+-dependent production of endothelial vasodilator autacoids such as NO, prostaglandin I2 and epoxides of arachidonic acid that mediate negative-feedback regulation of myogenic tone. Thus, Ca2+-dependent ion channels importantly contribute to many aspects of the regulation of myogenic tone in arterioles in the microcirculation.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, United States
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5
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Kumar T, Sharma M, Rana A, Lingaraju MC, Parida S, Kumar D, Singh TU. Biochanin-A elicits relaxation in coronary artery of goat through different mechanisms. Res Vet Sci 2020; 131:206-214. [PMID: 32408231 DOI: 10.1016/j.rvsc.2020.05.003] [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: 03/12/2019] [Revised: 04/25/2020] [Accepted: 05/02/2020] [Indexed: 12/19/2022]
Abstract
Flavonoids have shown beneficial effects in various disease conditions as reported by various previous studies. Biochanin-A is a flavonoid present in various plants in nature. Present investigation was done to assess the vasorelaxant potential of biochanin-A on isolated coronary artery of goat and its possible mechanism of action. Vascular reactivity experiments were done on circumflex coronary artery of goats using the tension experiments. Goat coronary arterial rings were relaxed with biochanin-A in concentration (0.1-100 μM)-dependent manner. Endothelium had no effect on biochanin-A-induced relaxation. Maximum relaxation induced by biochanin-A was 116.54 ± 12.21% in endothelium-intact artery and it was not significantly different with maximal relaxation (108.22 ± 1.88%) of endothelium-denuded vessel. L-NAME (100 μM) did not show any effect on biochanin-A-induced relaxation. TEA (BKCa channel blocker), and BaCl2 (KIR blocker) had no effect on biochanin-A-induced relaxation. However, biochanin-A-induced maximal relaxation (71.72 ± 4.50%) was reduced significantly (P < .001) in the presence of 4-aminopyridine (KV channel blocker, 3 mM) in comparison with control (114.07 ± 4.33%). Glibenclaminde (KATP channel blocker), H89 (PKA inhibitor), ICI182780 (estrogen receptor antagonist) showed partial attenuation in the biochanin-A-induced relaxation. ODQ (sGC blocker) and HC067047 (TRPV4 channel blocker) had no effect on biochanin-A-induced relaxation. In K+-depolarized endothelium-denuded arterial rings, biochanin-A (30 μM) significantly (P < .05; P < .001) decreased CaCl2-induced contractions (0.02 ± 0.01 g vs. control 0.73 ± 0.30 g). Biochanin-A did not influence the fasudil (rho kinase inhibitor) and SNP (NO-donor)-induced relaxation in this vessel. Biochanin-A showed relaxation in goat coronary artery in endothelium-independent pathways and showed the partial involvement of KATP, protein kinase A and estrogen receptors and full involvement of Cav1.2 channels.
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Affiliation(s)
- Tarun Kumar
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India
| | - Meemansha Sharma
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India
| | - Abhinav Rana
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India
| | - Madhu Cholenahalli Lingaraju
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India
| | - Subhashree Parida
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India
| | - Dinesh Kumar
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India
| | - Thakur Uttam Singh
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Izatnagar-243 122, Bareilly, Uttar Pradesh, India.
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6
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Ion channels and the regulation of myogenic tone in peripheral arterioles. CURRENT TOPICS IN MEMBRANES 2020; 85:19-58. [DOI: 10.1016/bs.ctm.2020.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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7
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Nishijima Y, Korishettar A, Chabowski DS, Cao S, Zheng X, Gutterman DD, Zhang DX. Shaker-related voltage-gated K + channel expression and vasomotor function in human coronary resistance arteries. Microcirculation 2018; 25. [PMID: 29161755 DOI: 10.1111/micc.12431] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/15/2017] [Indexed: 01/05/2023]
Abstract
OBJECTIVES KV channels are important regulators of vascular tone, but the identity of specific KV channels involved and their regulation in disease remain less well understood. We determined the expression of KV 1 channel subunits and their role in cAMP-mediated dilation in coronary resistance arteries from subjects with and without CAD. METHODS HCAs from patients with and without CAD were assessed for mRNA and protein expression of KV 1 channel subunits with molecular techniques and for vasodilator response with isolated arterial myography. RESULTS Assays of mRNA transcripts, membrane protein expression, and vascular cell-specific localization revealed abundant expression of KV 1.5 in vascular smooth muscle cells of non-CAD HCAs. Isoproterenol and forskolin, two distinct cAMP-mediated vasodilators, induced potent dilation of non-CAD arterioles, which was inhibited by both the general KV blocker 4-AP and the selective KV 1.5 blocker DPO-1. The cAMP-mediated dilation was reduced in CAD and was accompanied by a loss of or reduced contribution of 4-AP-sensitive KV channels. CONCLUSIONS KV 1.5, as a major 4-AP-sensitive KV 1 channel expressed in coronary VSMCs, mediates cAMP-mediated dilation in non-CAD arterioles. The cAMP-mediated dilation is reduced in CAD coronary arterioles, which is associated with impaired 4-AP-sensitive KV channel function.
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Affiliation(s)
- Yoshinori Nishijima
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Ankush Korishettar
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Dawid S Chabowski
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Sheng Cao
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Xiaodong Zheng
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - David D Gutterman
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin.,Zablocki Veterans Affairs Medical Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - David X Zhang
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
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8
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Jackson WF. K V channels and the regulation of vascular smooth muscle tone. Microcirculation 2018; 25. [PMID: 28985443 DOI: 10.1111/micc.12421] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/01/2017] [Indexed: 12/31/2022]
Abstract
VSMCs in resistance arteries and arterioles express a diverse array of KV channels with members of the KV 1, KV 2 and KV 7 families being particularly important. Members of the KV channel family: (i) are highly expressed in VSMCs; (ii) are active at the resting membrane potential of VSMCs in vivo (-45 to -30 mV); (iii) contribute to the negative feedback regulation of VSMC membrane potential and myogenic tone; (iv) are activated by cAMP-related vasodilators, hydrogen sulfide and hydrogen peroxide; (v) are inhibited by increases in intracellular Ca2+ and vasoconstrictors that signal through Gq -coupled receptors; (vi) are involved in the proliferative phenotype of VSMCs; and (vii) are modulated by diseases such as hypertension, obesity, the metabolic syndrome and diabetes. Thus, KV channels participate in every aspect of the regulation of VSMC function in both health and disease.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA
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9
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Lorigo M, Mariana M, Feiteiro J, Cairrao E. How is the human umbilical artery regulated? J Obstet Gynaecol Res 2018; 44:1193-1201. [PMID: 29727040 DOI: 10.1111/jog.13667] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 03/31/2018] [Indexed: 01/12/2023]
Abstract
The purpose of this review is to present an update of the main mechanisms involved in the physiological regulation of contraction and relaxation of the human umbilical artery (HUA) smooth muscle cells. A literature review was performed based on the analysis of papers available on PubMed. The most important and relevant studies regarding the regulation of the HUA are presented in this article. The vascular smooth muscle is a highly specialized structure, whose main function is to regulate the vascular tonus. This is controlled by a balance between the cellular signaling pathways that mediate contraction and relaxation. The cells responsible for the contractile property of this muscle are the smooth muscle cells (SMC), and an excellent source of these cells is the HUA, involved in fetoplacental circulation. Since the umbilical blood vessels are not innervated, the HUA tonus is modulated by vasoactive substances that regulate the contractile process. The main vasoactive substances that induce contraction are serotonin, histamine, thromboxane, bradykinin, endothelin 1 and prostaglandin F2α, that are linked to the activation of proteins Gq and Gi/0 . On the other hand, the main vasorelaxation mechanisms are the activation of adenyl and guanil cyclases, potassium channels and the inhibition of calcium channels. The SMC from the HUA allow the study of different cellular mechanisms and their functions. Therefore, these cells are an important tool to study the mechanisms regulating the contractility of this artery, allowing to detect potential therapeutic targets to treat HUA disorders (gestational hypertension and pre-eclampsia).
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Affiliation(s)
- Margarida Lorigo
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Melissa Mariana
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Joana Feiteiro
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Elisa Cairrao
- CICS-UBI, Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
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10
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The novel organic mononitrate NDHP attenuates hypertension and endothelial dysfunction in hypertensive rats. Redox Biol 2017; 15:182-191. [PMID: 29268201 PMCID: PMC5735329 DOI: 10.1016/j.redox.2017.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/30/2017] [Accepted: 12/06/2017] [Indexed: 01/13/2023] Open
Abstract
Rationale Development and progression of cardiovascular diseases, including hypertension, are often associated with impaired nitric oxide synthase (NOS) function and nitric oxide (NO) deficiency. Current treatment strategies to restore NO bioavailability with organic nitrates are hampered by undesirable side effects and development of tolerance. In this study, we evaluated NO release capability and cardiovascular effects of the newly synthesized organic nitrate 1, 3-bis (hexyloxy) propan-2-yl nitrate (NDHP). Methods A combination of in vitro and in vivo approaches was utilized to assess acute effects of NDHP on NO release, vascular reactivity and blood pressure. The therapeutic value of chronic NDHP treatment was assessed in an experimental model of angiotensin II-induced hypertension in combination with NOS inhibition. Results NDHP mediates NO formation in both cell-free system and small resistance arteries, a process which is catalyzed by xanthine oxidoreductase. NDHP-induced vasorelaxation is endothelium independent and mediated by NO release and modulation of potassium channels. Reduction of blood pressure following acute intravenous infusion of NDHP was more pronounced in hypertensive rats (two-kidney-one-clip model) than in normotensive sham-operated rats. Toxicological tests did not reveal any harmful effects following treatment with high doses of NDHP. Finally, chronic treatment with NDHP significantly attenuated the development of hypertension and endothelial dysfunction in rats with chronic NOS inhibition and angiotensin II infusion. Conclusion Acute treatment with the novel organic nitrate NDHP increases NO formation, which is associated with vasorelaxation and a significant reduction of blood pressure in hypertensive animals. Chronic NDHP treatment attenuates the progression of hypertension and endothelial dysfunction, suggesting a potential for therapeutic applications in cardiovascular disease. The organic nitrate NDHP mediates NO formation in cell-free system and blood vessels. NDHP-mediated NO release is dependent on functional XOR. NDHP induces endothelium-independent vasorelaxation and significant reduction of blood pressure. NDHP-mediated vasorelaxation involves activation of NO/cGMP/PKG pathway and K+ channels (Kv and BKCa). Chronic treatment with NDHP attenuates the development of hypertension and endothelial dysfunction.
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11
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Feng X, Zhou X, Zhang W, Li X, He A, Liu B, Shi R, Wu L, Wu J, Zhu D, Li N, Sun M, Xu Z. Maternal high-sucrose diets altered vascular large-conductance Ca2+-activated K+ channels via reactive oxygen species in offspring rats†. Biol Reprod 2017; 96:1085-1095. [DOI: 10.1093/biolre/iox031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 04/13/2017] [Indexed: 12/22/2022] Open
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12
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Jackson WF. Arteriolar oxygen reactivity: where is the sensor and what is the mechanism of action? J Physiol 2016; 594:5055-77. [PMID: 27324312 PMCID: PMC5023707 DOI: 10.1113/jp270192] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 06/13/2016] [Indexed: 01/02/2023] Open
Abstract
Arterioles in the peripheral microcirculation are exquisitely sensitive to changes in PO2 in their environment: increases in PO2 cause vasoconstriction while decreases in PO2 result in vasodilatation. However, the cell type that senses O2 (the O2 sensor) and the signalling pathway that couples changes in PO2 to changes in arteriolar tone (the mechanism of action) remain unclear. Many (but not all) ex vivo studies of isolated cannulated resistance arteries and large, first-order arterioles support the hypothesis that these vessels are intrinsically sensitive to PO2 with the smooth muscle, endothelial cells, or red blood cells serving as the O2 sensor. However, in situ studies testing these hypotheses in downstream arterioles have failed to find evidence of intrinsic O2 sensitivity, and instead have supported the idea that extravascular cells sense O2 . Similarly, ex vivo studies of isolated, cannulated resistance arteries and large first-order arterioles support the hypotheses that O2 -dependent inhibition of production of vasodilator cyclooxygenase products or O2 -dependent destruction of nitric oxide mediates O2 reactivity of these upstream vessels. In contrast, most in vivo studies of downstream arterioles have disproved these hypotheses and instead have provided evidence supporting the idea that O2 -dependent production of vasoconstrictors mediates arteriolar O2 reactivity, with significant regional heterogeneity in the specific vasoconstrictor involved. Oxygen-induced vasoconstriction may serve as a protective mechanism to reduce the oxidative burden to which a tissue is exposed, a process that is superimposed on top of the local mechanisms which regulate tissue blood flow to meet a tissue's metabolic demand.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, 48824, USA.
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14
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Abstract
KATP channels are integral to the functions of many cells and tissues. The use of electrophysiological methods has allowed for a detailed characterization of KATP channels in terms of their biophysical properties, nucleotide sensitivities, and modification by pharmacological compounds. However, even though they were first described almost 25 years ago (Noma 1983, Trube and Hescheler 1984), the physiological and pathophysiological roles of these channels, and their regulation by complex biological systems, are only now emerging for many tissues. Even in tissues where their roles have been best defined, there are still many unanswered questions. This review aims to summarize the properties, molecular composition, and pharmacology of KATP channels in various cardiovascular components (atria, specialized conduction system, ventricles, smooth muscle, endothelium, and mitochondria). We will summarize the lessons learned from available genetic mouse models and address the known roles of KATP channels in cardiovascular pathologies and how genetic variation in KATP channel genes contribute to human disease.
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Affiliation(s)
- Monique N Foster
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| | - William A Coetzee
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
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15
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Abstract
Ion channels are critical for all aspects of cardiac function, including rhythmicity and contractility. Consequently, ion channels are key targets for therapeutics aimed at cardiac pathophysiologies such as atrial fibrillation or angina. At the same time, off-target interactions of drugs with cardiac ion channels can be the cause of unwanted side effects. This manuscript aims to review the physiology and pharmacology of key cardiac ion channels. The intent is to highlight recent developments for therapeutic development, as well as elucidate potential mechanisms for drug-induced cardiac side effects, rather than present an in-depth review of each channel subtype.
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17
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Zhang HF, Chen XQ, Hu GY, Wang YP. Magnesium lithospermate B dilates mesenteric arteries by activating BKCa currents and contracts arteries by inhibiting K(V) currents. Acta Pharmacol Sin 2010; 31:665-70. [PMID: 20453873 DOI: 10.1038/aps.2010.40] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AIM To examine the involvement of K(+) channels and endothelium in the vascular effects of magnesium lithospermate B (MLB), a hydrophilic active component of Salviae miltiorrhiza Radix. METHODS Isolated rat mesenteric artery rings were employed to investigate the effects of MLB on KCl- or norepinephrine-induced contractions. Conventional whole-cell patch-clamp technique was used to study the effects of MLB on K(+) currents in single isolated mesenteric artery myocytes. RESULTS MLB produced a concentration-dependent relaxation in mesenteric artery rings precontracted by norepinephrine (1 micromol/L) with an EC(50) of 111.3 micromol/L. MLB-induced relaxation was reduced in denuded artery rings with an EC(50) of 224.4 micromol/L. MLB caused contractions in KCl-precontracted artery rings in the presence of N-nitro-L-arginine methyl ester (L-NAME) with a maximal value of 130.3%. The vasodilatory effect of MLB was inhibited by tetraethylammonium (TEA) in both intact and denuded artery rings. In single smooth muscle cells, MLB activated BK(Ca) currents (EC(50) 156.3 micromol/L) but inhibited K(V) currents (IC(50) 26.1 micromol/L) in a voltage- and concentration-dependent manner. CONCLUSION MLB dilated arteries by activating BK(Ca) channels in smooth muscle cells and increasing NO release from endothelium, but it also contracted arteries precontracted with KCl in the presence of L-NAME.
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18
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Nitric oxide and potassium channels mediate GM1 ganglioside-induced vasorelaxation. Naunyn Schmiedebergs Arch Pharmacol 2009; 380:487-95. [PMID: 19894035 DOI: 10.1007/s00210-009-0469-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Accepted: 10/15/2009] [Indexed: 12/13/2022]
Abstract
Monosialotetrahexosylganglioside (GM1) is a glycosphingolipid present in most cell membranes that displays antioxidant and neuroprotective properties. It has been recently described that GM1 induces pial vessel vasodilation and increases NO( x ) content in cerebral cortex, which are fully prevented by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). However, it is not known whether GM1 relaxes larger vessels, as well as the mechanisms by which GM1 causes vasorelaxation. In this study, we demonstrate that GM1 (10, 30, 100, 300 microM, 1 and 3 mM) induces vascular relaxation determined by isometric tension studies in rat mesenteric artery rings contracted with 1 microM phenylephrine. The vasorelaxation induced by GM1 was abolished by endothelium removal, by incubation with L-NAME (1 microM), and partially inhibited by the blockade of potassium channels by 1 mM tetraethylammonium, 10 microM glibenclamide, by the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (10 microM), and by 50 nM charybdotoxin, a blocker of large and intermediate conductance calcium-activated potassium channels. Moreover, GM1-induced relaxation was not affected by apamin (50 nM), a small conductance calcium-activated potassium channel blocker. The results indicate that direct and indirect nitric oxide pathways play a pivotal role in vasorelaxation induced by GM1, which is mediated mainly by potassium channels activation. We suggest that vasodilation may underlie some of the biological effects of exogenous GM1 ganglioside.
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19
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Zhao G, Zhao Y, Pan B, Liu J, Huang X, Zhang X, Cao C, Hou N, Wu C, Zhao KS, Cheng H. Hypersensitivity of BK
Ca
to Ca
2+
Sparks Underlies Hyporeactivity of Arterial Smooth Muscle in Shock. Circ Res 2007; 101:493-502. [PMID: 17641230 DOI: 10.1161/circresaha.107.157271] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Large conductance Ca
2+
-activated K
+
channels (BK
Ca
) play a critical role in blood pressure regulation by tuning the vascular smooth muscle tone, and hyposensitivity of BK
Ca
to Ca
2+
sparks resulting from its altered β1 subunit stoichiometry underlies vasoconstriction in animal models of hypertension. Here we demonstrate hypersensitivity of BK
Ca
to Ca
2+
sparks that contributes to hypotension and blunted vasoreactivity in acute hemorrhagic shock. In arterial smooth muscle cells under voltage-clamp conditions (0 mV), the amplitude and duration, but not the frequency, of spontaneous transient outward currents of BK
Ca
origin were markedly enhanced in hemorrhagic shock, resulting in a 265% greater hyperpolarizing current. Concomitantly, subsurface Ca
2+
spark frequency was either unaltered (at 0 mV) or decreased in hyperpolarized resting cells. Examining the relationship between spark and spontaneous transient outward current amplitudes revealed a hypersensitive BK
Ca
activity to Ca
2+
spark in hemorrhagic shock, whereas the spark–spontaneous transient outward current coupling fidelity was near unity in both groups. Importantly, we found an acute upregulation of the β1 subunit of the channel, and single-channel recording substantiated BK
Ca
hypersensitivity at micromolar Ca
2+
, which promotes the α and β1 subunit interaction. Treatment of shock animals with the BK
Ca
inhibitors iberiotoxin and charybdotoxin partially restored vascular membrane potential and vasoreactivity to norepinephrine and blood reinfusion. Thus, the results underscore a dynamic regulation of the BK
Ca
–Ca
2+
spark coupling and its therapeutic potential in hemorrhagic shock–associated vascular disorders.
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Affiliation(s)
- Guiling Zhao
- Department of Pathophysiology, Southern Medical University, Guangzhou, China
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20
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Malester B, Tong X, Ghiu I, Kontogeorgis A, Gutstein DE, Xu J, Hendricks-Munoz KD, Coetzee WA. Transgenic expression of a dominant negative K(ATP) channel subunit in the mouse endothelium: effects on coronary flow and endothelin-1 secretion. FASEB J 2007; 21:2162-72. [PMID: 17341678 DOI: 10.1096/fj.06-7821com] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
K(ATP) channels are involved in regulating coronary function, but the contribution of endothelial K(ATP) channels remains largely uncharacterized. We generated a transgenic mouse model to specifically target endothelial K(ATP) channels by expressing a dominant negative Kir6.1 subunit only in the endothelium. These animals had no obvious overt phenotype and no early mortality. Histologically, the coronary endothelium in these animals was preserved. There was no evidence of increased susceptibility to ergonovine-induced coronary vasospasm. However, isolated hearts from these animals had a substantially elevated basal coronary perfusion pressure. The K(ATP) channel openers, adenosine and levcromakalim, decreased the perfusion pressure whereas the K(ATP) channel blocker glibenclamide failed to produce a vasoconstrictive response. The inducible endothelial nitric oxide pathway was intact, as evidenced by vasodilation caused by bradykinin. In contrast, basal endothelin-1 release was significantly elevated in the coronary effluent from these hearts. Treatment of mice with bosentan (endothelin-1 receptor antagonist) normalized the coronary perfusion pressure, demonstrating that the elevated endothelin-1 release was sufficient to account for the increased coronary perfusion pressure. Pharmacological blockade of K(ATP) channels led to elevated endothelin-1 levels in the coronary effluent of isolated mouse and rat hearts as well as enhanced endothelin-1 secretion from isolated human coronary endothelial cells. These data are consistent with a role for endothelial K(ATP) channels to control the coronary blood flow by modulating the release of the vasoconstrictor, endothelin-1.
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Affiliation(s)
- Brian Malester
- Department of Pediatrics, NYU School of Medicine, 560 First Ave., New York, NY 10016, USA
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21
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Terasawa K, Nakajima T, Iida H, Iwasawa K, Oonuma H, Jo T, Morita T, Nakamura F, Fujimori Y, Toyo-oka T, Nagai R. Nonselective cation currents regulate membrane potential of rabbit coronary arterial cell: modulation by lysophosphatidylcholine. Circulation 2002; 106:3111-9. [PMID: 12473560 DOI: 10.1161/01.cir.0000039345.00481.1d] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The effects of lysophosphatidylcholine (LPC) on electrophysiological activities and intracellular Ca2+ concentration ([Ca2+]i) were investigated in coronary arterial smooth muscle cells (CASMCs). METHODS AND RESULTS The patch clamp techniques and Ca2+ measurements were applied to cultured rabbit CASMCs. The membrane potential was -46.0+/-5.0 mV, and LPC depolarized it. Replacement of extracellular Na+ with NMDG+ hyperpolarized the membrane and antagonized the depolarizing effects of LPC. In Na+-, K+-, or Cs+-containing solution, the voltage-independent background current with reversal potential (E(r)) of approximately +0 mV was observed. Removal of Cl- failed to affect it. When extracellular cations were replaced by NMDG+, E(r) was shifted to negative potentials. La3+ and Gd3+ abolished the background current, but nicardipine and verapamil did not inhibit it. In Na+-containing solution, LPC induced a voltage-independent current with E(r) of approximately +0 mV concentration-dependently. Similar current was recorded in K+- and Cs+-containing solution. La3+ and Gd3+ inhibited LPC-induced current, but nicardipine and verapamil did not inhibit it. In cell-attached configurations, single-channel activities with single-channel conductance of approximately 32pS were observed when patch pipettes were filled with LPC. LPC increased [Ca2+]i as the result of Ca2+ influx, and La3+ completely antagonized it. CONCLUSIONS These results suggest that (1) nonselective cation current (I(NSC)) contributes to form membrane potentials of CASMCs and (2) LPC activates I(NSC), resulting in an increase of [Ca2+]i. Thus, LPC may affect CASMC tone under various pathophysiological conditions such as ischemia.
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Affiliation(s)
- Kuniko Terasawa
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
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22
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Zhao KS, Huang X, Liu J, Huang Q, Jin C, Jiang Y, Jin J, Zhao G. New approach to treatment of shock--restitution of vasoreactivity. Shock 2002; 18:189-92. [PMID: 12166785 DOI: 10.1097/00024382-200208000-00017] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Our objective was to observe the therapeutic effect of restituting vasoreactivity agent in severe shock. A hemorrhagic shock (HS) model was reproduced in rat and the response of arterioles of spinotrapezius muscle to norepinephrine (NE) in HS was tested. The diameter, blood velocity, and volumetric flow in arteriole, and the mean arterial pressure (MAP) were measured. The therapeutic effect was observed after the treatment of restituting vasoreactivity agent (glybenclamide--an inhibitor of ATP sensitive potassium channel, and tiron--an oxygen free radical scavenger). The arteriolar vasoreactivity was significantly reduced with 15 fold increase of NE threshold 2 h post HS. After treated with restituting agent (RA), the vascular hyporeactivity of rat was apparently recovered, and the increased level of MAP following injection of dopamine was 1.8 times and 1.9 times more than that in NS-treated and DMSO-treated group respectively. After reinfusion of shed blood, the value of systemic blood pressure maintained more than 100 mmHg and volumetric flow in arterioles in RA group were 2 times more than those in NS treated group within the 2 h observation periods. The average survival time in RA treated group was also 1.8 times and 1.6 times longer than that in NS-treated and DMSO-treated group respectively. The restituting vasoreactivity agent is able to recover the lower vasoreactivity with excellent anti-shock effect in severe hemorrhagic shock.
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Affiliation(s)
- Ke-Seng Zhao
- Department of Pathophysiology, First Military Medical University, Guangzhou, China
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23
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Fukuda S, Schmid‐Schönbein GW. Centrifugation attenuates the fluid shear response of circulating leukocytes. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.1.133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Shunichi Fukuda
- Department of Bioengineering, The Whitaker Institute for Biomedical Engineering, University of California San Diego, La Jolla
| | - Geert W. Schmid‐Schönbein
- Department of Bioengineering, The Whitaker Institute for Biomedical Engineering, University of California San Diego, La Jolla
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24
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Simões C, Svensjö E, Bouskela E. Effects of cromakalim and glibenclamide on arteriolar and venular diameters and macromolecular leakage in the microcirculation during ischemia/reperfusion. J Cardiovasc Pharmacol 2002; 39:340-6. [PMID: 11862112 DOI: 10.1097/00005344-200203000-00004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We studied changes in arteriolar and venular diameters and macromolecular leakage altered by ischemia/reperfusion (I/R) and topically applied histamine after I/R and how these changes were modulated by cromakalim (KATP-channel opener) and glibenclamide (KATP-channel blocker). Golden hamsters were prepared for intravital microscopy of the cheek pouch. Ischemia was induced by an inflatable silicon rubber cuff mounted around the neck of the cheek pouch prepared for intravital microscopy. Saline, histamine, cromakalim, and glibenclamide were applied in the superfusion solution. FITC-dextran was injected i.v. 30 min before initiation of ischemia as a marker of macromolecular leakage. Cromakalim 10(-6) M, but not 10(-8) M, caused arteriolar dilation in ischemic and normal (nonischemic) preparations, and glibenclamide, 10 -10) M and 10(-8) M, had no effects on vessel diameters. Application of cromakalim 10(-6) M increased arteriolar diameter (+54%) and macromolecular leakage in normal and nonischemic cheek pouches and had an additive effect on macromolecular leakage in ischemic (I/R) preparations but had no effect on histamine-induced increase in macromolecular leakage. Glibenclamide, 10(-10) M and 10(-8) M, inhibited I/R-induced but not histamine-induced increases in macromolecular leakage. We concluded that cromakalim may increase macromolecular leakage. This effect is additive to I/R-induced leakage suggesting that stimulation of KATP-channels could take part in the regulation of macromolecular leakage in postcapillary venules. The KATP-blocker glibenclamide inhibited I/R-induced but not histamine-induced macromolecular leakage at concentrations that had no constricting effect on arterioles, and therefore, it cannot be excluded that glibenclamide reduced plasma leakage by some unknown mechanism.
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Affiliation(s)
- Claudia Simões
- Laboratório de Pesquisas em Microcirculação, Universidade do Estado do Rio de Janeiro, Rio de Janeiro RJ, Brazil
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25
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Côrtes SF, Rezende BA, Corriu C, Medeiros IA, Teixeira MM, Lopes MJ, Lemos VS. Pharmacological evidence for the activation of potassium channels as the mechanism involved in the hypotensive and vasorelaxant effect of dioclein in rat small resistance arteries. Br J Pharmacol 2001; 133:849-58. [PMID: 11454658 PMCID: PMC1572854 DOI: 10.1038/sj.bjp.0704147] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The hypotensive and vasorelaxant effect of dioclein in resistance mesenteric arteries was studied in intact animals and isolated vessels, respectively. In intact animals, initial bolus administration of dioclein (2.5 mg kg(-1)) produced transient hypotension accompanied by an increase in heart rate. Subsequent doses of dioclein (5 and 10 mg kg(-1)) produced hypotensive responses with no significant change in heart rate. N(G)-nitro-L-arginine methyl ester (L-NAME) did not affect the hypotensive response. In endothelium-containing or -denuded vessels pre-contracted with phenylephrine, dioclein (5 and 10 mg kg(-1) produced a concentration-dependent vasorelaxation (IC(50)=0.3+/-0.06 and 1.6+/-0.6 microM, respectively) which was not changed by 10 microM indomethacin. L-NAME (300 microM) produced a shift to the right. Dioclein was without effect on contraction of vessels induced by physiological salt solution (PSS) containing 50 mM KCl and the concentration dependence of dioclein's effect on phenylephrine induced contraction was shifted to the right in vessels bathed in PSS containing 25 mM KCl. Tetraethylammonium (10 mM) and BaCl(2) (1 mM) increased the IC(50) for dioclein-induced vasorelaxation without affecting the maximal response (E(max)). Charybdotoxin (100 nM), 4-aminopyridine (1 mM) and iberiotoxin (100 nM) increased the IC(50) and reduced the E(max). Apamin (1 microM) reduced the E(max) without affecting the IC(50). Dioclein produced a hyperpolarization in smooth muscle of mesenteric arteries with or without endothelium (7.7+/-1.4 mV and 12.3+/-3.6 mV, respectively). In conclusion dioclein lowered arterial pressure probably through a decrease in peripheral vascular resistance. The underling mechanism implicated in the vasorelaxant effect of dioclein appears to be the opening of K(Ca) and Kv channels and subsequent membrane hyperpolarization.
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Affiliation(s)
- Steyner F Côrtes
- Laboratório de Farmacologia Cardiovascular, Departamento de Farmacologia - ICB. Universidade Federal de Minas Gerais 31270 – 901, Belo Horizonte - Brazil
| | - Bruno A Rezende
- Departamento de Fisiologia e Biofísica - ICB. Universidade Federal de Minas Gerais. Belo Horizonte - Brazil
| | - Catherine Corriu
- Laboratoire de Pharmacologie et Physio-Chimie des Interactions Moléculaire et Cellulaires, URM CNRS 7034. Faculté de Pharmacie, Université Louis Pasteur de Strasbourg, Illkirch - France
| | - Isac A Medeiros
- Laboratório de Tecnologia Farmacêutica. Universidade Federal da Paraíba. João Pessoa - Brazil
| | - Mauro M Teixeira
- Laboratório de Farmacologia Cardiovascular, Departamento de Farmacologia - ICB. Universidade Federal de Minas Gerais 31270 – 901, Belo Horizonte - Brazil
| | - Miguel José Lopes
- Departamento de Fisiologia e Biofísica - ICB. Universidade Federal de Minas Gerais. Belo Horizonte - Brazil
| | - Virgínia S Lemos
- Departamento de Fisiologia e Biofísica - ICB. Universidade Federal de Minas Gerais. Belo Horizonte - Brazil
- Author for correspondence:
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26
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Horiuchi T, Dietrich HH, Tsugane S, Dacey RG. Role of potassium channels in regulation of brain arteriolar tone: comparison of cerebrum versus brain stem. Stroke 2001; 32:218-24. [PMID: 11136940 DOI: 10.1161/01.str.32.1.218] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Potassium channels are important regulators of resting tone in large cerebral arteries, but their activity and distribution may vary according to vessel location and species studied. In the cerebral microcirculation in vivo, however, these channels appear to be silent at rest. Our goal was to determine the activity of potassium channels of brain arterioles from 2 origins under basal conditions in vitro. METHODS Penetrating cerebral (40. 9+/-2.2 microm control diameter) and brain stem (36.2+/-1.2 microm) arterioles of rats were prepared from middle cerebral and basilar arteries, respectively. The internal diameter of cannulated and pressurized vessel was monitored with the inverted microscope before and after administration of potassium channel inhibitors. In addition, we studied the effect of nitric oxide synthase inhibition on potassium channel activity. RESULTS Cerebral and brain stem arterioles were significantly constricted by 4-aminopyridine and low concentration of BaCl(2) but not by glibenclamide. The addition of N:(omega)-nitro-L-arginine to 4-aminopyridine further decreased diameters of both arterioles. Tetraethylammonium ion caused a significant constriction of brain stem but not cerebral arteriole. The brain stem arteriole was further constricted by additional N:(omega)-nitro-L-arginine. CONCLUSIONS Voltage-dependent and inward-rectifier, but not ATP-sensitive, potassium channels are active under basal conditions of rat cerebral and brain stem arterioles. There is a regional difference in the activity of calcium-activated potassium channels, which, at rest, are open in brain stem but silent in cerebral arterioles. In addition, basal endogenous nitric oxide may not contribute to the activation of voltage-dependent and calcium-activated potassium channels.
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Affiliation(s)
- T Horiuchi
- Department of Neurosurgery, Washington University School of Medicine, St Louis, MO 63110, USA
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27
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Abstract
Ion channels in the plasma membrane of vascular muscle cells that form the walls of resistance arteries and arterioles play a central role in the regulation of vascular tone. Current evidence indicates that vascular smooth muscle cells express at least 4 different types of K(+) channels, 1 to 2 types of voltage-gated Ca(2+) channels, >/=2 types of Cl(-) channels, store-operated Ca(+) (SOC) channels, and stretch-activated cation (SAC) channels in their plasma membranes, all of which may be involved in the regulation of vascular tone. Calcium influx through voltage-gated Ca(2+), SOC, and SAC channels provides a major source of activator Ca(2+) used by resistance arteries and arterioles. In addition, K(+) and Cl(-) channels and the Ca(2+) channels mentioned previously all are involved in the determination of the membrane potential of these cells. Membrane potential is a key variable that not only regulates Ca(+2) influx through voltage-gated Ca(2+) channels, but also influences release of Ca(2+) from internal stores and Ca(2+)- sensitivity of the contractile apparatus. By controlling Ca(2+) delivery and membrane potential, ion channels are involved in all aspects of the generation and regulation of vascular tone.
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Affiliation(s)
- W F Jackson
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA.
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