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Lee Y, Zawieja SD, Muthuchamy M. Lymphatic Collecting Vessel: New Perspectives on Mechanisms of Contractile Regulation and Potential Lymphatic Contractile Pathways to Target in Obesity and Metabolic Diseases. Front Pharmacol 2022; 13:848088. [PMID: 35355722 PMCID: PMC8959455 DOI: 10.3389/fphar.2022.848088] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 02/17/2022] [Indexed: 01/19/2023] Open
Abstract
Obesity and metabolic syndrome pose a significant risk for developing cardiovascular disease and remain a critical healthcare challenge. Given the lymphatic system's role as a nexus for lipid absorption, immune cell trafficking, interstitial fluid and macromolecule homeostasis maintenance, the impact of obesity and metabolic disease on lymphatic function is a burgeoning field in lymphatic research. Work over the past decade has progressed from the association of an obese phenotype with Prox1 haploinsufficiency and the identification of obesity as a risk factor for lymphedema to consistent findings of lymphatic collecting vessel dysfunction across multiple metabolic disease models and organisms and characterization of obesity-induced lymphedema in the morbidly obese. Critically, recent findings have suggested that restoration of lymphatic function can also ameliorate obesity and insulin resistance, positing lymphatic targeted therapies as relevant pharmacological interventions. There remain, however, significant gaps in our understanding of lymphatic collecting vessel function, particularly the mechanisms that regulate the spontaneous contractile activity required for active lymph propulsion and lymph return in humans. In this article, we will review the current findings on lymphatic architecture and collecting vessel function, including recent advances in the ionic basis of lymphatic muscle contractile activity. We will then discuss lymphatic dysfunction observed with metabolic disruption and potential pathways to target with pharmacological approaches to improve lymphatic collecting vessel function.
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Affiliation(s)
- Yang Lee
- Department of Medical Physiology, College of Medicine, Texas A&M University, Bryan, TX, United States
| | - Scott D Zawieja
- Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Mariappan Muthuchamy
- Department of Medical Physiology, College of Medicine, Texas A&M University, Bryan, TX, United States
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Clinical Importance of the Human Umbilical Artery Potassium Channels. Cells 2020; 9:cells9091956. [PMID: 32854241 PMCID: PMC7565333 DOI: 10.3390/cells9091956] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023] Open
Abstract
Potassium (K+) channels are usually predominant in the membranes of vascular smooth muscle cells (SMCs). These channels play an important role in regulating the membrane potential and vessel contractility-a role that depends on the vascular bed. Thus, the activity of K+ channels represents one of the main mechanisms regulating the vascular tone in physiological and pathophysiological conditions. Briefly, the activation of K+ channels in SMC leads to hyperpolarization and vasorelaxation, while its inhibition induces depolarization and consequent vascular contraction. Currently, there are four different types of K+ channels described in SMCs: voltage-dependent K+ (KV) channels, calcium-activated K+ (KCa) channels, inward rectifier K+ (Kir) channels, and 2-pore domain K+ (K2P) channels. Due to the fundamental role of K+ channels in excitable cells, these channels are promising therapeutic targets in clinical practice. Therefore, this review discusses the basic properties of the various types of K+ channels, including structure, cellular mechanisms that regulate their activity, and new advances in the development of activators and blockers of these channels. The vascular functions of these channels will be discussed with a focus on vascular SMCs of the human umbilical artery. Then, the clinical importance of K+ channels in the treatment and prevention of cardiovascular diseases during pregnancy, such as gestational hypertension and preeclampsia, will be explored.
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Alterations of ATP-sensitive K + channels in human umbilical arterial smooth muscle during gestational diabetes mellitus. Pflugers Arch 2018; 470:1325-1333. [PMID: 29855712 DOI: 10.1007/s00424-018-2154-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 04/11/2018] [Accepted: 05/09/2018] [Indexed: 12/20/2022]
Abstract
We investigated the alterations of ATP-sensitive K+ (KATP) channels in human umbilical arterial smooth muscle cells during gestational diabetes mellitus (GDM). The amplitude of the KATP current induced by application of the KATP channel opener pinacidil (10 μM) was reduced in the GDM group than in the control group. Pinacidil-induced vasorelaxation was also predominant in the normal group compared with the GDM group. Reverse transcription polymerase chain reaction and Western blot analysis suggested that the expression of KATP channel subunits such as Kir6.1, Kir6.2, and SUR2B were decreased in the GDM group relative to the normal group. The application of forskolin and adenosine, which activates protein kinase A (PKA) and thereby KATP channels, elicited KATP current in both the normal and GDM groups. However, the current amplitudes were not different between the normal and GDM groups. In addition, the expression levels of PKA subunits were not altered between the two groups. These results suggest that the reduction of KATP current and KATP channel-induced vasorelaxation are due to the decreased expression of KATP channels, not to the impairment of KATP-related signaling pathways.
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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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Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:89-144. [PMID: 28212804 DOI: 10.1016/bs.apha.2016.07.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells.
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Wang SY, Cui WY, Wang H. The new antihypertensive drug iptakalim activates ATP-sensitive potassium channels in the endothelium of resistance blood vessels. Acta Pharmacol Sin 2015; 36:1444-50. [PMID: 26592519 DOI: 10.1038/aps.2015.97] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 07/12/2015] [Indexed: 11/09/2022] Open
Abstract
AIM To investigate the mechanisms underlying the activation of ATP-sensitive potassium channels (K(ATP)) by iptakalim in cultured rat mesenteric microvascular endothelial cells (MVECs). METHODS Whole-cell KATP currents were recorded in MVECs using automated patch clamp devices. Nucleotides (ATP, ADP and UDP) were added to the internal perfusion system, whereas other drugs were added to the cell suspension on NPC-1 borosilicate glass chips. RESULTS Application of iptakalim (10 and 100 μmol/L) significantly increased the whole-cell K(ATP) currents, which were prevented by the specific K(ATP) blocker glibenclamide (1.0 μmol/L). The opening of K(ATP) channels by iptakalim depended upon the intracellular concentrations of ATP or NDPs: iptakalim activated K(ATP) channels when the intracellular ATP or NDPs were at 100 or 1000 μmol/L, and was ineffective when the non-hydrolysable ATP analogue ATPγS (1000 μmol/L) was infused into the cells. In contrast, the K(ATP) opener pinacidil activated K(ATP) channels when the intracellular concentrations of ATP or NDPs ranged from 10 to 5000 μmol/L, and even ATPγS (1000 μmol/L) was infused into the cells. CONCLUSION Iptakalim activates K(ATP) channels in the endothelial cells of resistance blood vessels with a low metabolic status, and this activation is dependent on both ATP hydrolysis and ATP ligands.
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Characterization of imidazoline receptors in blood vessels for the development of antihypertensive agents. BIOMED RESEARCH INTERNATIONAL 2014; 2014:182846. [PMID: 24800210 PMCID: PMC3996295 DOI: 10.1155/2014/182846] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 03/09/2014] [Indexed: 01/01/2023]
Abstract
It has been indicated that activation of peripheral imidazoline I2-receptor (I-2R) may reduce the blood pressure in spontaneously hypertensive rats (SHRs). Also, guanidinium derivatives show the ability to activate imidazoline receptors. Thus, it is of special interest to characterize the I-2R using guanidinium derivatives in blood vessels for development of antihypertensive agent(s). Six guanidinium derivatives including agmatine, amiloride, aminoguanidine, allantoin, canavanine, and metformin were applied in this study. Western blot analysis was used for detecting the expression of imidazoline receptor in tissues of Wistar rats. The isometric tension of aortic rings isolated from male rats was also estimated. The expression of imidazoline receptor on rat aorta was identified. However, guanidinium derivatives for detection of aortic relaxation were not observed except agmatine and amiloride which induced a marked relaxation in isolated aortic rings precontracted with phenylephrine or KCl. Both relaxations induced by agmatine and amiloride were attenuated by glibenclamide at concentration enough to block ATP-sensitive potassium (KATP) channels. Meanwhile, only agmatine-induced relaxation was abolished by BU224, a selective antagonist of imidazoline I2-receptors. Taken together, we suggest that agmatine can induce vascular relaxation through activation of peripheral imidazoline I2-receptor to open KATP channels. Thus, agmatine-like compound has the potential to develop as a new therapeutic agent for hypertension in the future.
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Stott JB, Jepps TA, Greenwood IA. KV7 potassium channels: a new therapeutic target in smooth muscle disorders. Drug Discov Today 2014; 19:413-24. [DOI: 10.1016/j.drudis.2013.12.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/21/2013] [Accepted: 12/04/2013] [Indexed: 12/23/2022]
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Priestley JRC, Buelow MW, McEwen ST, Weinberg BD, Delaney M, Balus SF, Hoeppner C, Dondlinger L, Lombard JH. Reduced angiotensin II levels cause generalized vascular dysfunction via oxidant stress in hamster cheek pouch arterioles. Microvasc Res 2013; 89:134-45. [PMID: 23628292 PMCID: PMC3758804 DOI: 10.1016/j.mvr.2013.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/19/2013] [Accepted: 04/18/2013] [Indexed: 11/23/2022]
Abstract
OBJECTIVES We investigated the effect of suppressing plasma angiotensin II (ANG II) levels on arteriolar relaxation in the hamster cheek pouch. METHODS Arteriolar diameters were measured via television microscopy during short-term (3-6days) high salt (HS; 4% NaCl) diet and angiotensin converting enzyme (ACE) inhibition with captopril (100mg/kg/day). RESULTS ACE inhibition and/or HS diet eliminated endothelium-dependent arteriolar dilation to acetylcholine, endothelium-independent dilation to the NO donor sodium nitroprusside, the prostacyclin analogs carbacyclin and iloprost, and the KATP channel opener cromakalim; and eliminated arteriolar constriction during KATP channel blockade with glibenclamide. Scavenging of superoxide radicals and low dose ANG II infusion (25ng/kg/min, subcutaneous) reduced oxidant stress and restored arteriolar dilation in arterioles of HS-fed hamsters. Vasoconstriction to topically-applied ANG II was unaffected by HS diet while arteriolar responses to elevation of superfusion solution PO2 were unaffected (5% O2, 10% O2) or reduced (21% O2) by HS diet. CONCLUSIONS These findings indicate that sustained exposure to low levels of circulating ANG II leads to widespread dysfunction in endothelium-dependent and independent vascular relaxation mechanisms in cheek pouch arterioles by increasing vascular oxidant stress, but does not potentiate O2- or ANG II-induced constriction of arterioles in the distal microcirculation of normotensive hamsters.
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Mar GY, Chou MT, Chung HH, Chiu NH, Chen MF, Cheng JT. Changes of imidazoline receptors in spontaneously hypertensive rats. Int J Exp Pathol 2012; 94:17-24. [PMID: 23176371 DOI: 10.1111/iep.12000] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 07/13/2012] [Indexed: 12/27/2022] Open
Abstract
The role of imidazoline receptors in the regulation of vascular function remains unclear. In this study, we evaluated the effect of agmatine, an imidazoline receptor agonist, on systolic blood pressure (SBP) in spontaneously hypertensive rats (SHRs) and investigated the expressions of imidazoline receptors by Western blot. The isometric tension of aortic rings isolated from male SHRs was also estimated. Agmatine decreased SBP in a dose-dependent manner in SHRs but not in the normal group [Wistar-Kyoto (WKY) rats]. This reduction in SBP in SHRs was abolished by BU224, a selective antagonist of imidazoline I(2) -receptors. Higher expression of imidazoline receptors in SHR was observed. Moreover, agmatine-induced relaxation in isolated aortic rings precontracted with phenylephrine or KCl. This relaxation was also abolished by BU224 but was not modified by efaroxan, an imidazoline I(1) -receptor antagonist. Agmatine-induced relaxation was also attenuated by PNU 37883, a selective blocker of vascular ATP-sensitive potassium (K(ATP) ) channels. Additionally, vasodilatation by agmatine was reduced by an inhibitor of protein kinase A (PKA). We suggest that agmatine can lower blood pressure in SHRs through activation of the peripheral imidazoline I(2) -receptor, which is expressed more highly in SHRs.
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Affiliation(s)
- Guang-Yuan Mar
- Department of Cardiology, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan
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Park WS, Hong DH, Son YK, Kim MH, Jeong SH, Kim HK, Kim N, Han J. Alteration of ATP-sensitive K+ channels in rabbit aortic smooth muscle during left ventricular hypertrophy. Am J Physiol Cell Physiol 2012; 303:C170-8. [PMID: 22572849 DOI: 10.1152/ajpcell.00041.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the impairment of ATP-sensitive K(+) (K(ATP)) channels in aortic smooth muscle cells (ASMCs) from isoproterenol-induced hypertrophied rabbits. The amplitude of K(ATP) channels induced by the K(ATP) channel opener pinacidil (10 μM) was greater in ASMCs from control than from hypertrophied animals. In phenylephrine-preconstricted aortic rings, pinacidil induced relaxation in a dose-dependent manner. The dose-dependent curve was shifted to the right in the hypertrophied (EC(50): 17.80 ± 3.28 μM) compared with the control model (EC(50): 6.69 ± 2.40 μM). Although the level of Kir6.2 subtype expression did not differ between ASMCs from the control and hypertrophied models, those of the Kir6.1 and SUR2B subtypes were decreased in the hypertrophied model. Application of the calcitonin-gene related peptide (100 nM) and adenylyl cyclase activator forskolin (10 μM), which activates protein kinase A (PKA) and consequently K(ATP) channels, induced a K(ATP) current in both control and hypertrophied animals; however, the K(ATP) current amplitude did not differ between the two groups. Furthermore, PKA expression was not altered between the control and hypertrophied animals. These results suggests that the decreased K(ATP) current amplitude and K(ATP) channel-induced vasorelaxation in the hypertrophied animals were attributable to the reduction in K(ATP) channel expression but not to changes in the intracellular signaling mechanism that activates the K(ATP) current.
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Affiliation(s)
- Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Korea
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Chen ZC, Shieh JP, Chung HH, Hung CH, Lin HJ, Cheng JT. Activation of peripheral opioid µ-receptors in blood vessel may lower blood pressure in spontaneously hypertensive rats. Pharmacology 2011; 87:257-64. [PMID: 21494057 DOI: 10.1159/000326084] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 02/14/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS The role of opioid receptors in the regulation of vascular function remains unclear. In the current study, we evaluated the ability of loperamide, a peripheral opioid receptor agonist, to regulate blood pressure in spontaneously hypertensive rats (SHRs) and examined the mechanism(s) by which loperamide exerts its effects. METHODS In male SHRs, mean arterial pressure (MAP) was measured and hemodynamic analysis was recorded. Additionally, the isometric tension of aortic rings isolated from SHRs was determined. RESULTS Loperamide dose-dependently decreased MAP in SHRs but not in the normal group of Wistar-Kyoto rats. This reduction of MAP in conscious SHRs was abolished by the selective opioid μ-receptor antagonist cyprodime, but not by naloxonazine, the μ(1)-opioid receptor antagonist. However, cardiac output was not altered by loperamide in anesthetized SHRs. Moreover, loperamide-induced relaxation in isolated aortic rings precontracted with phenylephrine or vasopressin. This relaxation was abolished by cyprodime, but not by naloxonazine. Loperamide-induced relaxation was also attenuated by glibenclamide, an ATP-sensitive potassium (K(ATP)) channel blocker. Additionally, vasodilatation by loperamide was reduced by an inhibitor of protein kinase A (PKA) and enhanced by an inhibitor of phosphodiesterases. CONCLUSION We suggest that loperamide can lower MAP in SHRs via μ(2)-opioid receptor-dependent cAMP-PKA pathway that induces vascular relaxation by opening K(ATP) channels.
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Affiliation(s)
- Zhih-Cherng Chen
- Department of Cardiology, Chi-Mei Medical Center, Yong Kang, Tainan City, Taiwan, ROC
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Role of vascular K(ATP) channels in blood pressure variability after sinoaortic denervation in rats. Acta Pharmacol Sin 2011; 32:194-200. [PMID: 21293472 DOI: 10.1038/aps.2010.195] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
AIM To investigate the role of ATP-sensitive potassium (K(ATP)) channels on blood pressure variability (BPV) in sinoaortic denervated (SAD) rats. METHODS SAD was performed on male Sprague-Dawley rats 4 weeks before the study. mRNA expression of Kir6.1, Kir6.2 and SUR2 in aorta and mesenteric artery was determined using real-time quantitative polymerase chain reaction, and confirmed at the protein level using Western blotting and laser confocal immunofluorescence assays. Concentration-response curves of isolated aortic and mesenteric arterial rings to adenosine and pinacidil were established. Effects of K(ATP) channel openers and blocker on BPV were examined in conscious SAD rats. RESULTS Aortic SUR2 expression was significantly greater, while Kir6.1 was lower, in SAD rats than in sham-operated controls. In contrast, in the mesenteric artery both SUR2 and Kir6.1 expression were markedly lower in SAD rats than controls. For both arteries, Kir6.2 expression was indistinguishable between sham-operated and SAD rats. These findings were confirmed at the protein level. Responses of the aorta to both adenosine and pinacidil were enhanced after SAD, while the mesenteric response to adenosine was attenuated. Pinacidil, diazoxide, nicorandil, and glibenclamide significantly decreased BPV. CONCLUSION These findings indicate that expression of vascular K(ATP) channels is altered by chronic SAD. These alterations influence vascular reactivity, and may play a role in the increased BPV in chronic SAD rats.
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Xiao D, Longo LD, Zhang L. Role of KATP and L-type Ca2+ channel activities in regulation of ovine uterine vascular contractility: effect of pregnancy and chronic hypoxia. Am J Obstet Gynecol 2010; 203:596.e6-12. [PMID: 20817142 PMCID: PMC2993850 DOI: 10.1016/j.ajog.2010.07.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 07/09/2010] [Accepted: 07/21/2010] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Our objective was to determine whether the pregnancy and high altitude long-term hypoxia-mediated changes in uterine artery contractility were regulated by K(ATP) and L-type Ca(2+) channel activities. STUDY DESIGN Uterine arteries were isolated from nonpregnant and near-term pregnant ewes that had been maintained at sea level (∼300 m) or exposed to high altitude (3801 m) for 110 days. Isometric tension was measured in a tissue bath. RESULTS Pregnancy increased diazoxide, but not verapamil-induced relaxations. Long-term hypoxia attenuated diazoxide-induced relaxations in near-term pregnant uterine arteries, but enhanced verapamil-induced relaxations in nonpregnant uterine arteries. Diazoxide decreased the maximal response (E(max)) of phenylephrine-induced contractions in near-term pregnant uterin arteries but not nonpregnant uterine arteries in normoxic sheep. In contrast, diazoxide had no effect on phenylephrine-induced E(max) in near-term pregnant uterine arteries but decreased it in nonpregnant uterine arteries in long-term hypoxia animals. Verapamil decreased the E(max) and pD(2) (-logEC(50)) of phenylephrine-induced contractions in both nonpregnant uterine arteries and near-term pregnant uterine arteries in normoxic and long-term hypoxia animals, except nonpregnant uterine arteries of normoxic animals in which verapamil showed no effect on the pD(2). CONCLUSION The results suggest that pregnancy selectively increases K(ATP), but not L-type Ca(2+) channel activity. Long-term hypoxia decreases the K(ATP) channel activity, which may contribute to the enhanced uterine vascular myogenic tone observed in pregnant sheep at high altitude hypoxia.
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Affiliation(s)
- Daliao Xiao
- Center for Perinatal Biology, Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA, USA
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Fan LH, Tian HY, Wang J, Huo JH, Hu Z, Ma AQ, Cao YX. Downregulation of Kir6.1/SUR2B channels in the obese rat aorta. Nutrition 2008; 25:359-63. [PMID: 19056241 DOI: 10.1016/j.nut.2008.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 08/10/2008] [Accepted: 09/02/2008] [Indexed: 11/29/2022]
Abstract
OBJECTIVE This study was designed to evaluate the contribution of adenosine triphosphate-dependent potassium channels to the increase in blood pressure observed in obese rats. METHODS The experiment was performed in male Sprague-Dawley rats. Glibenclamide-sensitive currents were measured in vascular smooth muscle cells by patch-clamp. Expressions of Kir6.1 and SUR2B were examined by reverse transcription polymerase chain reaction and western blot techniques, respectively. RESULTS In the aortic vascular smooth muscle cells, pinacidil induced glibenclamide-sensitive currents. The current from obese rats was significantly lower (-10.55 +/- 1.63 pA/pF) compared with that from the control rats (-20.18 +/- 2.79 pA/pF). Expressions of Kir6.1 and SUR2B were downregulated in vascular smooth muscle cells of aortas from the obese rats. CONCLUSION These findings suggest that the adenosine triphosphate-dependent potassium channel is downregulated in smooth muscle cells from the aortas of obese rats, which may contribute to the increase in blood pressure in these rats.
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Affiliation(s)
- Li-Hong Fan
- Department of Cardiology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
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Fan LH, Tian HY, Ma AQ, Hu Z, Huo JH, Cao YX. Altered ATP-sensitive potassium channels may underscore obesity-triggered increase in blood pressure. Acta Pharmacol Sin 2008; 29:1167-74. [PMID: 18817620 DOI: 10.1111/j.1745-7254.2008.00810.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
AIM To determine whether ATP-sensitive potassium channels are altered in VSMC from arotas and mesenteric arteries of obese rat, and their association with obesity-triggered increase in blood pressure. METHODS Obesity was induced by 24 weeks of high-fat diet feeding in male Sprague-Dawley rats. Control rats were fed with standard laboratory rat chow. Blood pressure and body weight of these rats were measured every 4 weeks. At the end of 24 weeks, K(ATP) channelmediated relaxation responses in the aortas and mesenteric arteries, K(ATP) channel current, and gene expression were examined, respectively. RESULTS Blood pressure and body weight were increased in rats fed with high-fat diet. K(ATP) channelmediated relaxation responses, currents, and K(ATP) expression in VSMC of both aortas and mesenteric arteries were inhibited in these rats. CONCLUSION Altered ATP-sensitive potassium channels in obese rats may underscore obesity-triggered increase in blood pressure.
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Affiliation(s)
- Li-hong Fan
- Department of Cardiology, The First Affiliated Hospital of Xi-an Jiaotong University School of Medicine, Xi-an 710061, China
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Park WS, Han J, Earm YE. Physiological role of inward rectifier K+ channels in vascular smooth muscle cells. Pflugers Arch 2008; 457:137-47. [DOI: 10.1007/s00424-008-0512-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/19/2008] [Accepted: 03/25/2008] [Indexed: 10/22/2022]
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Blanco-Rivero J, Gamallo C, Aras-López R, Cobeño L, Cogolludo A, Pérez-Vizcaino F, Ferrer M, Balfagon G. Decreased expression of aortic KIR6.1 and SUR2B in hypertension does not correlate with changes in the functional role of K(ATP) channels. Eur J Pharmacol 2008; 587:204-8. [PMID: 18471810 DOI: 10.1016/j.ejphar.2008.03.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 02/26/2008] [Accepted: 03/10/2008] [Indexed: 11/15/2022]
Abstract
ATP-dependent potassium (K(ATP)) channels are the target of multiple vasoactive factors and drugs. Changes in the functional role of ATP-dependent (K(ATP)) potassium channels in hypertension are controversial. The aim of the present study was to analyze the possible changes of ATP-sensitive potassium channels (K(ATP)) expression and function during hypertension. For this purpose, we used endothelium-denuded aorta segments from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) to analyze the 1) expression of K(ATP) subunits Kir6.1, Kir6.2 and SUR2B by immunohistochemistry and Western blot, 2) the K(ATP) currents recorded in the whole cell configuration of the patch-clamp technique and 3) the vasodilator response to the K(ATP) channel openers, pinacidil and cromakalim. Kir6.1 and SUR2B were expressed in the medial layer of the aorta from WKY rats and SHR rats, while Kir6.2 was not detected in aorta from either strain. Kir6.1 and SUR2B expression were decreased in hypertension. However, the vasodilator responses of pinacidil and cromakalim were similar in WKY rats and SHR rats. Moreover, pinacidil induced increase in K+ currents was also similar in WKY rats and SHR rats and also similarly inhibited by glybenclamide. Our data demonstrate for the first time direct evidence of decreased aortic Kir6.1/SUR2B subunit expression in hypertension, but preserved functional responses to K(ATP) channel openers.
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Affiliation(s)
- Javier Blanco-Rivero
- Department of Physiology, School of Medicine, Universidad Autonoma de Madrid, Spain
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Ko EA, Han J, Jung ID, Park WS. Physiological roles of K + channels in vascular smooth muscle cells. J Smooth Muscle Res 2008; 44:65-81. [DOI: 10.1540/jsmr.44.65] [Citation(s) in RCA: 317] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Eun A Ko
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondria Research Group, Department of Physiology and Biophysics, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University
| | - Jin Han
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondria Research Group, Department of Physiology and Biophysics, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University
| | - In Duk Jung
- Department of Microbiology and Immunology and National Research Laboratory of Dentritic, Cell Differentiation and Regulation, Pusan National University, College of Medicine
| | - Won Sun Park
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondria Research Group, Department of Physiology and Biophysics, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University
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Ding L, Chapman A, Boyd R, Wang HD. ERK activation contributes to regulation of spontaneous contractile tone via superoxide anion in isolated rat aorta of angiotensin II-induced hypertension. Am J Physiol Heart Circ Physiol 2007; 292:H2997-3005. [PMID: 17308007 DOI: 10.1152/ajpheart.00388.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arteries from hypertensive animals and humans have increased spontaneous tone. Increased superoxide anion (superoxide) contributes to elevated blood pressure (BP) and spontaneous tone in hypertension. The association between the extracellular signaling-regulated kinase 1/2 (ERK1/2)-mitogen-activated protein kinase (MAPK) signaling pathway and generation of superoxide and spontaneous tone in isolated aorta was studied in angiotensin II (ANG II)-infused hypertensive (HT) rats. Systolic BP, phosphorylation of ERK, aortic superoxide formation, and aortic spontaneous tone were compared in sham normotensive and HT rats. Infusion of ANG II (0.5 mg x kg(-1) x day(-1) for 6 days) significantly elevated the systolic BP (P<0.01). The phosphorylation of ERK1/2 vs. total ERK1/2 in thoracic aorta was enhanced, and superoxide was increased in the HT vs. the sham group (P<0.01). Spontaneous tone developed in the HT group, but not in the normotensive group. MAPK/ERK1/2 (MEK1/2)-ERK1/2 signaling pathway inhibitors, PD-98059 (10 micromol/l), and U-0126 (10 micromol/l), significantly reduced the phosphorylation of ERK1/2, superoxide generation (P<0.01), and spontaneous tone (P<0.01) in HT. These findings suggest that ANG II infusion induces the production of superoxide and spontaneous tone and that both are dependent on ERK-MAPK activation. In endothelium-denuded aorta, however, MEK1/2 inhibitors did not inhibit the spontaneous tone, even though they significantly reduced superoxide generation similar to endothelium-intact aorta. These data suggest that inhibition of ERK1/2 signaling pathway, via PD-98059 or U-0126, may regulate spontaneous tone in an endothelium-dependent manner. In conclusion, these findings support the importance of the ERK1/2 signaling pathway in modulating vascular oxidative stress and subsequently mediating spontaneous tone in HT.
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Affiliation(s)
- Lili Ding
- Department of Community Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3Y6, Canada
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Lee TM, Lin MS, Tsai CH, Chang NC. Effect of pravastatin on left ventricular mass in the two-kidney, one-clip hypertensive rats. Am J Physiol Heart Circ Physiol 2006; 291:H2705-13. [PMID: 16798829 DOI: 10.1152/ajpheart.00224.2006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have demonstrated that myocardial ATP-sensitive potassium (KATP) channels are implicated in the development of cardiac hypertrophy in hyperlipidemic rabbits. We investigated the effect of pravastatin on development of ventricular hypertrophy in male normolipidemic Wistar rats with two-kidney, one-clip (2K1C) hypertension and whether the attenuated hypertrophic effect was via activation of KATPchannels. Twenty-four hours after the left renal artery was clipped, rats were treated with one of the following therapies for 8 wk: vehicle, nicorandil (an agonist of KATPchannels), pravastatin, glibenclamide (an antagonist of KATPchannels), hydralazine, nicorandil plus glibenclamide, or pravastatin plus glibenclamide. Systolic blood pressure, relative left ventricular (LV) weight, and cardiomyocyte sizes significantly increased in vehicle-treated 2K1C rats compared with those in sham-operated rats. Treatment with either nicorandil or pravastatin significantly attenuated LV hypertrophy/body weight compared with the vehicle, which was further confirmed by downregulation of LV atrial natriuretic peptide mRNA. Nicorandil-induced effects were abolished by administering glibenclamide. Similarly, pravastatin-induced beneficial effects were reversed by the addition of glibenclamide, implicating KATPchannels as the relevant target. A dissociation between the effects of blood pressure and cardiac structure was noted because pravastatin and hydralazine reduced arterial pressure similarly. These results suggest a crucial role of cardiac KATPchannel system in the development of ventricular hypertrophy in the 2K1C hypertensive rats. Pravastatin is endowed with cardiac antihypertrophic properties probably through activation of KATPchannels, independent of lipid and hemodynamic changes.
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Affiliation(s)
- Tsung-Ming Lee
- Cardiology Section, Dept. of Medicine, Taipei Medical University, Chi-Mei Medical Center, Taipei, 110, Taiwan
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Kim J, Lee YR, Lee CH, Choi WH, Lee CK, Kim J, Bae YM, Cho S, Kim B. Mitogen-activated protein kinase contributes to elevated basal tone in aortic smooth muscle from hypertensive rats. Eur J Pharmacol 2005; 514:209-15. [PMID: 15910808 DOI: 10.1016/j.ejphar.2005.03.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 03/15/2005] [Accepted: 03/21/2005] [Indexed: 10/25/2022]
Abstract
The role of mitogen-activated protein kinase (MAPK) in increased basal tone -spontaneous resistance in vascular muscle strips- was clarified in aortic smooth muscle from deoxycorticosterone acetate (DOCA)-salt hypertensive rats. The MAPK/extracellular signal-regulated protein kinase (ERK) kinase inhibitor, PD098059 (2'-amino-3'-methoxyflavone), significantly inhibited basal tone in a dose-dependent manner. The basal level of ERK1/2 activation was inhibited by PD098059 and was significantly greater in hypertensive rats than in sham-operated rats. In contrast, inhibition with PD098059 was not observed in sham-operated rats. GF109203X (2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl)maleimide), an inhibitor of protein kinase C (PKC), decreased both basal tone and ERK1/2 activity in the hypertensive rats. In contrast, Y27632 ((R)-(+)-trans-N-(4-Pyridyl)-4-(1-aminoethyl)cyclohexanecarboxamide) and verapamil, inhibitors of Rho kinase and voltage-dependent Ca2+ channels, respectively, significantly inhibited basal tone but not ERK1/2 activity. Thus, basal vascular tone is elevated by the altered activation of MAPK in DOCA-salt hypertensive rats, and this is regulated by PKC, but not by Rho or intracellular Ca2+.
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Affiliation(s)
- Junghwan Kim
- Department of Physiology, College of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Danwol-dong 322, Choongju 380-701, Korea
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