1
|
Al-Brakati AY, Kamishima T, Dart C, Quayle JM. Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels. PeerJ 2015; 3:e966. [PMID: 26038721 PMCID: PMC4451037 DOI: 10.7717/peerj.966] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/29/2015] [Indexed: 12/22/2022] Open
Abstract
Background and Purpose. Caveolae act as signalling hubs in endothelial and smooth muscle cells. Caveolar disruption by the membrane cholesterol depleting agent methyl-β-cyclodextrin (M-β-CD) has various functional effects on arteries including (i) impairment of endothelium-dependent relaxation, and (ii) alteration of smooth muscle cell (SMC) contraction independently of the endothelium. The aim of this study was to explore the effects of M-β-CD on rat femoral arteries. Methods. Isometric force was measured in rat femoral arteries stimulated to contract with a solution containing 20 mM K(+) and 200 nM Bay K 8644 (20 K/Bay K) or with one containing 80 mM K(+)(80 K). Results. Incubation of arteries with M-β-CD (5 mM, 60 min) increased force in response to 20 K/Bay K but not that induced by 80 K. Application of cholesterol saturated M-β-CD (Ch-MCD, 5 mM, 50 min) reversed the effects of M-β-CD. After mechanical removal of endothelial cells M-β-CD caused only a small enhancement of contractions to 20 K/Bay K. This result suggests M-β-CD acts via altering release of an endothelial-derived vasodilator or vasoconstrictor. When nitric oxide synthase was blocked by pre-incubation of arteries with L-NAME (250 µM) the contraction of arteries to 20 K/Bay K was enhanced, and this effect was abolished by pre-treatment with M-β-CD. This suggests M-β-CD is inhibiting endothelial NO release. Inhibition of large conductance voltage- and Ca(2+)-activated (BKCa) channels with 2 mM TEA(+) or 100 nM Iberiotoxin (IbTX) enhanced 20 K/Bay K contractions. L-NAME attenuated the contractile effect of IbTX, as did endothelial removal. Conclusions. Our results suggest caveolar disruption results in decreased release of endothelial-derived nitric oxide in rat femoral artery, resulting in a reduced contribution of BKCa channels to the smooth muscle cell membrane potential, causing depolarisation and contraction.
Collapse
Affiliation(s)
- AY Al-Brakati
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - T Kamishima
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - C Dart
- Department of Biochemistry and Cell Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - JM Quayle
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| |
Collapse
|
2
|
Marinko M, Novakovic A, Nenezic D, Stojanovic I, Milojevic P, Jovic M, Ugresic N, Kanjuh V, Yang Q, He GW. Nicorandil directly and cyclic GMP-dependently opens K+ channels in human bypass grafts. J Pharmacol Sci 2015; 128:59-64. [PMID: 25850381 DOI: 10.1016/j.jphs.2015.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 02/08/2015] [Accepted: 03/10/2015] [Indexed: 02/07/2023] Open
Abstract
As we previously demonstrated the role of different K(+) channels in the action of nicorandil on human saphenous vein (HSV) and human internal mammary artery (HIMA), this study aimed to analyse the contribution of the cGMP pathway in nicorandil-induced vasorelaxation and to determine the involvement of cGMP in the K(+) channel-activating effect of nicorandil. An inhibitor of soluble guanylate cyclase (GC), ODQ, significantly inhibited nicorandil-induced relaxation, while ODQ plus glibenclamide, a selective ATP-sensitive K(+) (KATP) channel inhibitor, produced a further inhibition of both vessels. In HSV, ODQ in combination with 4-aminopyridine, a blocker of voltage-gated K(+) (KV) channels, did not modify the concentration-response to nicorandil compared with ODQ, whereas in HIMA, ODQ plus iberiotoxin, a selective blocker of large-conductance Ca(2+)-activated K(+) (BKCa) channels, produced greater inhibition than ODQ alone. We showed that the cGMP pathway plays a significant role in the vasorelaxant effect of nicorandil on HSV and HIMA. It seems that nicorandil directly opens KATP channels in both vessels and BKCa channels in HIMA, although it is possible that stimulation of GC contributes to KATP channels activation in HIMA. Contrary, the activation of KV channels in HSV is probably due to GC activation and increased levels of cGMP.
Collapse
Affiliation(s)
- Marija Marinko
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Aleksandra Novakovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.
| | - Dragoslav Nenezic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Ivan Stojanovic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Predrag Milojevic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Miomir Jovic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Nenad Ugresic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | | | - Qin Yang
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong; TEDA International Cardiovascular Hospital, Medical College, Nankai University, Tianjin, China
| | - Guo-Wei He
- TEDA International Cardiovascular Hospital, Medical College, Nankai University, Tianjin, China; Providence Heart & Vascular Institute, Albert Starr Academic Center, Department of Surgery, Oregon Health and Science University, Portland, OR, USA
| |
Collapse
|
3
|
Calcium influx inhibition is involved in the hypotensive and vasorelaxant effects induced by yangambin. Molecules 2014; 19:6863-76. [PMID: 24858272 PMCID: PMC6271947 DOI: 10.3390/molecules19056863] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 05/13/2014] [Accepted: 05/15/2014] [Indexed: 11/17/2022] Open
Abstract
The pharmacological effects on the cardiovascular system of yangambin, a lignan isolated from Ocotea duckei Vattimo (Lauraceae), were studied in rats using combined functional and biochemical approaches. In non-anaesthetized rats, yangambin (1, 5, 10, 20, 30 mg/kg, i.v.) induced hypotension (−3.5 ± 0.2; −7.1 ± 0.8; −8.9 ± 1.3; −14 ± 2.3, −25.5% ± 2.6%, respectively) accompanied by tachycardia (5.9 ± 0.5; 5.9 ± 1.6; 8.8 ± 1.4; 11.6, 18.8% ± 3.4%, respectively). In isolated rat atria, yangambin (0.1 µM–1 mM) had very slight negative inotropic (Emax = 35.6% ± 6.4%) and chronotropic effects (Emax = 10.2% ± 2.9%). In endothelium-intact rat mesenteric artery, yangambin (0.1 µM–1 mM) induced concentration-dependent relaxation (pD2 = 4.5 ± 0.06) of contractions induced by phenylephrine and this effect was not affected by removal of the endothelium. Interestingly, like nifedipine, the relaxant effect induced by yangambin was more potent on the contractile response induced by KCl 80 mM (pD2 = 4.8 ± 0.05) when compared to that induced by phenylephrine. Furthermore, yangambin inhibited CaCl2-induced contractions in a concentration-dependent manner. This lignan also induced relaxation (pD2 = 4.0 ± 0.04) of isolated arteries pre-contracted with S(−)-Bay K 8644. In fura-2/AM-loaded myocytes of rat mesenteric arteries, yangambin inhibited the Ca2+ signal evoked by KCl 60 mM. In conclusion, these results suggest that the hypotensive effect of yangambin is probably due to a peripheral vasodilatation that involves, at least, the inhibition the Ca2+ influx through voltage-gated Ca2+ channels.
Collapse
|
4
|
Wang ZQ, Xu JF, Wang JP, Zhao WJ, Zeng M. Involvement of guanylate cyclase and K+ channels in relaxation evoked by ferulate nitrate in rat aorta artery. J Pharmacol Sci 2013; 118:521-30. [PMID: 22510967 DOI: 10.1254/jphs.11179fp] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Vasorelaxant properties of N-2-(ferulamidoethyl)-nitrate (ferulate nitrate, FLNT), a newly synthesized nitrate, were compared with those of isosorbide dinitrate, nicorandil, nitroglycerin, and 8-bromoguanosine 3,5-cyclic monophosphate (8-Br-cGMP) in rat aorta pre-contracted by phenylephrine. FLNT produced vasorelaxation in a concentration-dependent manner (0.1 - 100 µM). The degree of relaxation induced by FLNT was similar to that induced by isosorbide dinitrate. In addition, removal of endothelium did not affect the relaxant effect of FLNT. FLNT caused a rightward shift of the cumulative concentration-response curves of phenylephrine and reduced the maximal efficacy of contraction. 1H-[1,2,4]Oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 µM) and K(+)-channel blockers charybdotoxin (CHT, 0.1 µM) and BaCl(2) (1 µM) reduced the relaxant effect of FLNT in the endothelium-denuded arteries, whereas glibenclamide (1 µM) and 4-aminopyridine (1 mM) failed to influence FLNT-induced vasorelaxation. Furthermore, in the presence of ODQ, both CHT (0.1 µM) and BaCl(2) (1 µM) still significantly reduced the relaxation evoked by FLNT. Pretreatment of vessels with hydroxocobalamin, a nitric oxide scavenger, abolished the FLNT effect. These findings demonstrate that FLNT induces relaxation of the rat aorta rings endothelium-independently. Furthermore, we demonstrated that FLNT-induced vasorelaxation is related to its stimulation of soluble guanylate cyclase and activation of K(+) channels.
Collapse
Affiliation(s)
- Zhan-Qing Wang
- Department of Pharmacology, General Hospital of Beijing Military Command, Beijing, China.
| | | | | | | | | |
Collapse
|
5
|
Novakovic A, Pavlovic M, Milojevic P, Stojanovic I, Nenezic D, Jovic M, Ugresic N, Kanjuh V, Yang Q, He GW. Different potassium channels are involved in relaxation of rat renal artery induced by P1075. Basic Clin Pharmacol Toxicol 2012; 111:24-30. [PMID: 22225832 DOI: 10.1111/j.1742-7843.2011.00855.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 12/16/2011] [Indexed: 11/28/2022]
Abstract
The ATP-sensitive K(+) channels opener (K(ATP)CO), P1075 [N-cyano-N'-(1,1-dimethylpropyl)-N″-3-pyridylguanidine], has been shown to cause relaxation of various isolated animal and human blood vessels by opening of vascular smooth muscle ATP-sensitive K(+) (K(ATP)) channels. In addition to the well-known effect on the opening of K(ATP) channels, it has been reported that vasorelaxation induced by some of the K(ATP)COs includes some other K(+) channel subtypes. Given that there is still no information on other types of K(+) channels possibly involved in the mechanism of relaxation induced by P1075, this study was designed to examine the effects of P1075 on the rat renal artery with endothelium and with denuded endothelium and to define the contribution of different K(+) channel subtypes in the P1075 action on this blood vessel. Our results show that P1075 induced a concentration-dependent relaxation of rat renal artery rings pre-contracted by phenylephrine. Glibenclamide, a selective K(ATP) channels inhibitor, partly antagonized the relaxation of rat renal artery induced by P1075. Tetraethylammonium (TEA), a non-selective inhibitor of Ca(2+)-activated K(+) channels, as well as iberiotoxin, a most selective blocker of large-conductance Ca(2+) -activated K(+) (BK(Ca)) channels, did not abolish the effect of P1075 on rat renal artery. In contrast, a non-selective blocker of voltage-gated K(+) (K(V)) channels, 4-aminopyridine (4-AP), as well as margatoxin, a potent inhibitor of K(V)1.3 channels, caused partial inhibition of the P1075-induced relaxation of rat renal artery. In addition, in this study, P1075 relaxed contractions induced by 20 mM K(+) , but had no effect on contractions induced by 80 mM K(+). Our results showed that P1075 induced strong endothelium-independent relaxation of rat renal artery. It seems that K(ATP), 4-AP- and margatoxin-sensitive K(+) channels located in vascular smooth muscle mediated the relaxation of rat renal artery induced by P1075.
Collapse
Affiliation(s)
- Aleksandra Novakovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Serbia.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Different K+ Channels Are Involved in Relaxation of Arterial and Venous Graft Induced by Nicorandil. J Cardiovasc Pharmacol 2011; 58:602-8. [DOI: 10.1097/fjc.0b013e31823003f2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
7
|
Suto Y, Oshima K, Arakawa K, Sato H, Yamazaki H, Matsumoto K, Takeyoshi I. The effect of nicorandil on small intestinal ischemia-reperfusion injury in a canine model. Dig Dis Sci 2011; 56:2276-82. [PMID: 21360281 DOI: 10.1007/s10620-011-1623-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 02/07/2011] [Indexed: 12/09/2022]
Abstract
BACKGROUND It has been shown that nicorandil, which has both ATP-sensitive K+ (KATP) channel opener-like and nitrate-like properties, has an organ-protective effect in ischemia-reperfusion injury in several experimental animal models. AIMS We evaluate the effectiveness of nicorandil on warm ischemia-reperfusion injury of the small intestine in a canine model. METHODS Eighteen beagle dogs were divided into three groups: the control group (n=6); the nicorandil group (n=6), to which nicorandil was injected intravenously before the ischemia; and the glibenclamide group (n=6), to which glibenclamide, which closes the KATP channel and does not suppress the nitrate effect of nicorandil, was orally administered, and then nicorandil was injected in the same manner as in the nicorandil group. Both the superior mesenteric artery and vein were clamped for 2 h. Superior mesenteric artery blood flow, small intestinal mucosal tissue blood flow, intramucosal pH, and histopathological analyses were compared among the three groups. RESULTS Superior mesenteric artery blood flow, mucosal tissue blood flow and pHi after reperfusion were significantly maintained in the nicorandil in comparison with the control and the glibenclamide groups. The histopathological findings showed less severe mucosal damage after reperfusion in the nicorandil group compared with the other two groups. Between the control group and the glibenclamide group, no significant differences were observed in all those parameters. CONCLUSION This study suggests that nicorandil has a protective effect on small intestinal IR injury, and activation of KATP channels plays an important role in inhibiting small intestinal IR injury.
Collapse
Affiliation(s)
- Yujin Suto
- Department of Thoracic and Visceral Organ Surgery, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | | | | | | | | | | | | |
Collapse
|
8
|
Tang G, Wu L, Liang W, Wang R. Direct stimulation of K(ATP) channels by exogenous and endogenous hydrogen sulfide in vascular smooth muscle cells. Mol Pharmacol 2005; 68:1757-64. [PMID: 16150926 DOI: 10.1124/mol.105.017467] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ATP-sensitive K+ (K(ATP)) channels in vascular smooth muscle cells (VSMC) are important targets for endogenous metabolic regulation and exogenous drug therapy. H2S, as a novel gasotransmitter, has been shown to relax rat aortic tissues via opening of K(ATP) channels. However, interaction of H2S, exogenous-applied or endogenous-produced, with K(ATP) channels in resistance artery VSMC has not been delineated. In the present study, using the whole-cell and single-channel patch-clamp technique, we demonstrated that exogenous H2S activated K(ATP) channels and hyperpolarized cell membrane in rat mesenteric artery VSMC. H2S enhanced the amplitude of whole-cell K(ATP) currents with an EC50 value of 116 +/- 8.3 microM and increased the open probability of single K(ATP) channels. H2S hyperpolarized membrane potentials by -12 mV in nystatin-perforated VSMC. Furthermore, inhibition of endogenous H2S production with D,L-propargylglycine (PPG) reduced whole-cell K(ATP) currents. PPG alone had no effect on unitary K(ATP) channel currents in cell-free membrane patches. In addition, effects of H2S on K(ATP) channels and membrane potentials were independent of cGMP-mediated phosphorylation. This study demonstrated modulation of K(ATP) channel activity by exogenous and endogenous H2S in resistance artery VSMC, thus helping elucidate cardiovascular functions of this endogenous gas.
Collapse
Affiliation(s)
- Guanghua Tang
- FAHA, Department of Physiology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | | | | | | |
Collapse
|
9
|
Cao C, Lee-Kwon W, Silldorff EP, Pallone TL. KATP channel conductance of descending vasa recta pericytes. Am J Physiol Renal Physiol 2005; 289:F1235-45. [PMID: 16048905 DOI: 10.1152/ajprenal.00111.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using nystatin-perforated patch-clamp and whole cell recording, we tested the hypothesis that K(ATP) channels contribute to resting conductance of rat descending vasa recta (DVR) pericytes and are modulated by vasoconstrictors. The K(ATP) blocker glybenclamide (Glb; 10 microM) depolarized pericytes and inhibited outward currents of cells held at -40 mV. K(ATP) openers pinacidil (Pnc; 10 microM) and P-1075 (1 microM) hyperpolarized pericytes and transiently augmented outward currents. All effects of Pnc and P-1075 were fully reversed by Glb. Inward currents of pericytes held at -60 mV in symmetrical 140 mM K(+) were markedly augmented by Pnc and fully reversed by Glb. Ramp depolarizations in symmetrical K(+), performed in Pnc and Pnc + Glb, yielded a Pnc-induced, Glb-sensitive K(ATP) difference current that lacked rectification and reversed at 0 mV. Immunostaining identified both K(IR)6.1, K(IR)6.2 inward rectifier subunits and sulfonurea receptor subtype 2B. ANG II (1 and 10 nM) and endothelin-1 (10 nM) but not vasopressin (100 nM) significantly lowered holding current at -40 mV and abolished Pnc-stimulated outward currents. We conclude that DVR pericytes express K(ATP) channels that make a significant contribution to basal K(+) conductance and are inhibited by ANG II and endothelin-1.
Collapse
Affiliation(s)
- Chunhua Cao
- Division of Nephrology, Department of Medicine, University of Maryland, Baltimore, 21201, USA
| | | | | | | |
Collapse
|
10
|
Gollasch M, Dubrovska G. Paracrine role for periadventitial adipose tissue in the regulation of arterial tone. Trends Pharmacol Sci 2004; 25:647-53. [PMID: 15530643 DOI: 10.1016/j.tips.2004.10.005] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Recent studies propose a paracrine role for periadventitial adipose tissue in the regulation of vascular tone. This regulation depends on the anatomical integrity of the periadventitial adipose tissue and involves adipocyte-derived relaxing factor (ADRF). Although the nature of ADRF is largely unknown, it is released by periadventitial adipocytes and induces vasorelaxation by opening K+ channels in the plasma membrane of smooth muscle cells. Alterations in the paracrine role of periadventitial adipose tissue might have a role in vascular dysfunction in hypertension and metabolic disease. Therefore, understanding alterations in ADRF release and the K+ channels involved will help further our understanding of the increased cardiovascular risk and development of chronic vascular disease in obesity. Furthermore, ADRF and perhaps its putative targets might represent exciting new targets for the development of drugs to treat cardiovascular disorders.
Collapse
Affiliation(s)
- Maik Gollasch
- LSU Health Sciences Center, Physiology, 1901 Perdido Street, Box P7-3, New Orleans, LA 70112-1393, USA.
| | | |
Collapse
|
11
|
Verlohren S, Dubrovska G, Tsang SY, Essin K, Luft FC, Huang Y, Gollasch M. Visceral Periadventitial Adipose Tissue Regulates Arterial Tone of Mesenteric Arteries. Hypertension 2004; 44:271-6. [PMID: 15302842 DOI: 10.1161/01.hyp.0000140058.28994.ec] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Periadventitial adipose tissue produces vasoactive substances that influence vascular contraction. Earlier studies addressed this issue in aorta, a vessel that does not contribute to peripheral vascular resistance. We tested the hypothesis that periadventitial adipose tissue modulates contraction of smaller arteries more relevant to blood pressure regulation. We studied mesenteric artery rings surrounded by periadventitial adipose tissue from adult male Sprague-Dawley rats. The contractile response to serotonin, phenylephrine, and endothelin I was markedly reduced in intact vessels compared with vessels without periadventitial fat. The contractile response to U46619 or depolarizing high K
+
-containing solutions (60 mmol/L) was similar in vessels with and without periadventitial fat. The K
+
channel opener cromakalim induced relaxation of vessels precontracted by serotonin but not by U46619 or high K
+
-containing solutions (60 mmol/L), suggesting that K
+
channels are involved. The intracellular membrane potential of smooth muscle cells was more hyperpolarized in intact vessels than in vessels without periadventitial fat. Both the anticontractile effect and membrane hyperpolarization of periadventitial fat were abolished by inhibition of delayed-rectifier K
+
(K
v
) channels with 4-aminopyridine (2 mmol/L) or 3,4-diaminopyridine (1 mmol/L). Blocking other K
+
channels with glibenclamide (3 μmol/L), apamin (1 μmol/L), iberiotoxin (100 nmol/L), tetraethylammonium ions (1 mmol/L), tetrapentylammonium ions (10 μmol/L), or Ba
2+
(3 μmol/L) had no effect. Longitudinal removal of half the perivascular tissue reduced the anticontractile effect of fat by almost 50%, whereas removal of the endothelium had no effect. We suggest that visceral periadventitial adipose tissue controls mesenteric arterial tone by inducing vasorelaxation via K
v
channel activation in vascular smooth muscle cells.
Collapse
Affiliation(s)
- Stefan Verlohren
- Franz Volhard Clinic and Max Delbrück Center for Molecular Medicine, Charité University Hospitals, Humboldt University of Berlin, HELIOS Klinikum Berlin, Germany
| | | | | | | | | | | | | |
Collapse
|
12
|
Cheng Y, Ndisang JF, Tang G, Cao K, Wang R. Hydrogen sulfide-induced relaxation of resistance mesenteric artery beds of rats. Am J Physiol Heart Circ Physiol 2004; 287:H2316-23. [PMID: 15191893 DOI: 10.1152/ajpheart.00331.2004] [Citation(s) in RCA: 327] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hydrogen sulfide (H2S) has been shown recently to function as an important gasotransmitter. The present study investigated the vascular effects of H2S, both exogenously applied and endogenously generated, on resistance mesenteric arteries of rats and the underlying mechanisms. Both H2S and NaHS evoked concentration-dependent relaxation of in vitro perfused rat mesenteric artery beds (MAB). The sensitivity of MAB to H2S (EC50, 25.2 +/- 3.6 microM) was about fivefold higher than that of rat aortic tissues. Removal of endothelium or coapplication of charybdotoxin and apamin to endothelium-intact MAB significantly reduced the vasorelaxation effects of H2S. The H2S-induced relaxation of MAB was partially mediated by ATP-sensitive K+ (KATP) channel activity in vascular smooth muscle cells. Pinacidil (EC50, 1.7 +/- 0.1 microM, n=6) mimicked, but glibenclamide (10 microM, n=6) suppressed, the vasorelaxant effect of H2S. KATP channel currents in isolated mesenteric artery smooth muscle cells were significantly augmented by H2S. L-cysteine, a substrate of cystathionine-gamma-lyase (CSE), at 1 mM increased endogenous H2S production by sixfold in rat mesenteric artery tissues and decreased contractility of MAB. DL-propargylglycine (a blocker of CSE) at 10 microM abolished L-cysteine-dependent increase in H2S production and relaxation of MAB. Our results demonstrated a tissue-specific relaxant response of resistance arteries to H2S. The stimulation of KATP channels in vascular smooth muscle cells and charybdotoxin/apamin-sensitive K+ channels in vascular endothelium by H2S represents important cellular mechanisms for H2S effect on MAB. Our study also demonstrated that endogenous CSE can generate sufficient H2S from exogenous L-cysteine to cause vasodilation. Future studies are merited to investigate direct contribution of endogenous H2S to regulation of vascular tone.
Collapse
Affiliation(s)
- Youqin Cheng
- Dept. of Physiology, College of Medicine, Univ. of Saskatchewan, 107 Wiggins Rd., Saskatoon, Saskatchewan, Canada S7N 5E5
| | | | | | | | | |
Collapse
|
13
|
Wei XM, Heywood GJ, Di Girolamo N, Thomas PS. Nicorandil inhibits the release of TNFα from a lymphocyte cell line and peripheral blood lymphocytes. Int Immunopharmacol 2003; 3:1581-8. [PMID: 14555283 DOI: 10.1016/s1567-5769(03)00176-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Modulation of cytokine release may be of interest in modulating inflammatory diseases. This study determined whether nicorandil, a potassium channel opener, and nitric oxide (NO) donor could inhibit the release of tumour necrosis factor alpha (TNFalpha) from lymphocytes. Nicorandil significantly and dose-dependently inhibited the TNFalpha release from a human Epstein Barr virus-transformed B lymphocyte cell line (EBV-B) and peripheral blood B and T lymphocytes. The inhibition was reversed by the addition of both potassium channel inhibitor glibenclamide and the guanylyl cyclase inhibitor 1H-(1,2,4) oxadiazolo (4,3) quinoxalin-1-one (ODQ). Other potassium channel openers, pinacidil, or the nicorandil analogue SG-209, however, failed to demonstrate inhibition of TNFalpha release. The NO scavenger haemoglobin was unable to reverse the nicorandil-induced TNFalpha inhibition, but in contrast to this, sodium nitroprusside (SNP) partially inhibited the release, which was reversed by haemoglobin. Nicorandil is able to inhibit TNFalpha release from lymphocytes, which requires the dual modes of both potassium channel opening and the nitrate moiety. Moreover, NO donation mechanism appears to be more dominant in the nicorandil inhibitory activity in lymphocytes.The dual mechanism involved in the inhibition of this cytokines may represent a novel therapeutical approach in the modulation of inflammatory disease.
Collapse
Affiliation(s)
- X M Wei
- Inflammation Research Unit, School of Pathology, Faculty of Medicine, UNSW and Department of Respiratory Medicine, Prince of Wales Hospital, NSW 2031, Randwick, Australia
| | | | | | | |
Collapse
|
14
|
Abstract
A novel concept of "gasotransmitter" arrived recently. Gasotransmitters are small molecules of endogenous gases with important physiological functions. Their production and metabolism are enzymatically regulated, and their effects are not dependent on specific membrane receptors. Following the identification of nitric oxide and carbon monoxide as gasotransmitters, hydrogen sulfide (H(2)S) may be qualified as the third gasotransmitter. Recent studies have shown that H(2)S is generated from vascular smooth muscle cells (SMCs), catalyzed by specific H(2)S-generating enzyme. At physiologically relevant concentrations, H(2)S relaxes vascular tissues, an effect mediated by the activation of ATP-sensitive K(+) (K(ATP)) channels in vascular SMCs. H(2)S directly alters the activity of K(ATP) channels without the involvement of second messengers. Furthermore, the endogenous production of H(2)S in the cardiovascular system is likely regulated by nitric oxide, whereas the vasorelaxant effect of nitric oxide is inhibited by H(2)S. It is anticipated that future studies will better reveal the molecular mechanisms underlying the effect of H(2)S on K(ATP) channel proteins, the interaction of H(2)S and other gasotransmitters in cardiovascular system, the endogenous stimulators and inhibitors of H(2)S metabolism, the role of H(2)S in the regulation of heart function, and the abnormal H(2)S production and action under various pathophysiological conditions.
Collapse
Affiliation(s)
- Rui Wang
- Department of Physiology, University of Saskatchewan, Saskatoon, SK, S7N 5E5 Canada.
| |
Collapse
|
15
|
Abstract
ATP-sensitive potassium channels (K(ATP)) of vascular smooth muscle cells represent potential therapeutic targets for control of abnormal vascular contractility. The biophysical properties, regulation and pharmacology of these channels have received intense scrutiny during the past twenty years, however, the molecular basis of vascular K(ATP) channels remains ill-defined. This review summarizes the recent advancements made in our understanding of the molecular composition of vascular K(ATP) channels with a focus on the evidence that hetero-octameric complexes of Kir6.1 and SUR2B subunits constitute the vascular K(ATP) subtype responsible for control of arterial diameter by vasoactive agonists.
Collapse
Affiliation(s)
- William C Cole
- The Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
| | | |
Collapse
|
16
|
Yang Q, Zou W, Yim AP, Arifi AA, He GW. Role of sarcolemmal and mitochondrial KATP channels and EDHF-mediated relaxation in coronary microarteries. Drug Dev Res 2003. [DOI: 10.1002/ddr.10136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
17
|
Cao K, Tang G, Hu D, Wang R. Molecular basis of ATP-sensitive K+ channels in rat vascular smooth muscles. Biochem Biophys Res Commun 2002; 296:463-9. [PMID: 12163042 DOI: 10.1016/s0006-291x(02)00892-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
ATP-sensitive K+ (K(ATP)) channels couple metabolic changes to membrane excitability in vascular smooth muscle cells (SMCs). While the electrophysiological properties of K(ATP) channels have been examined, little is known about the molecular basis of K(ATP) complex in vascular SMCs. We identified and cloned four K(ATP) subunit genes from rat mesenteric artery, namely rvKir6.1, rvKir6.2, rvKirSUR1, and rvSUR2B. These clones showed over 99.6% amino acid sequence identity with other previously reported isoforms. The mRNA expression patterns of the K(ATP) subunits varied among rat aorta, mesenteric artery, pulmonary artery, tail artery, hepatic artery, and portal vein. Heterologous co-expression of rvKir6.1 and rvSUR2B yielded functional K(ATP) channels that were inhibited by glibenclamide, and opened by pinacidil. Our results for the first time reported the expression of four K(ATP) subunits in same vascular tissues, unmasking the diversity of native K(ATP) channels in vascular SMCs.
Collapse
Affiliation(s)
- Kun Cao
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | | | | | | |
Collapse
|
18
|
Dairaku Y, Miura T, Harada N, Kimura M, Okamura T, Iwamoto H, Kametani R, Yamada M, Ikeda Y, Iwatate M, Kawamura S, Matsuzaki M. Effect of ischemic preconditioning and mitochondrial KATP channel openers on chronic left ventricular remodeling in the ischemic-reperfused rat heart. Circ J 2002; 66:411-5. [PMID: 11954959 DOI: 10.1253/circj.66.411] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The influence of ischemic preconditioning (IP) and mitochondrial ATP-sensitive potassium (mito-KATP) channel openers on chronic left ventricular (LV) remodeling remains unknown, so the effect of IP and mito-KATP channel openers on the LV pressure-volume curve was assessed in rats subjected to 30 min ischemia followed by a 3-week reperfusion. Infarct size was histologically determined at 3 weeks after reperfusion. The LV pressure-volume curve was significantly shifted left by IP, diazoxide and nicorandil compared with the controls. These effects were blocked by the selective mito-KATP channel blocker 5-hydroxydecanoate. The LV remodeling and the infarct size at 3 weeks after reperfusion correlated well, indicating that the reduction of LV remodeling in the ischemic-reperfused model was strongly influenced by attenuation of the ischemic injury. LV remodeling in the chronic phase is attenuated by IP and mito-KATP channel openers with concomitant reduction of infarct size.
Collapse
Affiliation(s)
- Yuka Dairaku
- Department of Cardiovascular Medicine, Medical Bioregulation, Yamaguchi University School of Medicine, Ube, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Davie CS, Everitt DE, Standen NB. Increase in the vasorelaxant potency of K(ATP) channel opening drugs by adenosine A(1) and A(2) receptors in the pig coronary artery. Eur J Pharmacol 1999; 383:155-62. [PMID: 10585529 DOI: 10.1016/s0014-2999(99)00635-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myograph recording from ring segments of pig small coronary arteries was used to investigate the effects of adenosine receptor activation on the vasorelaxant potency of ATP-sensitive K(+) channel opening drugs. Receptor activation with 2-chloroadenosine (2-CA, 300 nM) increased the potency of both nicorandil and levcromakalim, shifting the pEC(50)s from 4.68+/-0.03 to 5.05+/-0.04 and from 6.34+/-0.06 to 6.72+/-0.06, respectively (P<0.05 in each case). Experiments with selective adenosine receptor agonists (2-chloro-N(6)-cyclopentyladenosine (CCPA), 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS 21680)) and antagonists (8-cyclopentyl-1, 3-dipropylxanthine (DPCPX), 4-(2-[7-amino-2-(2-furyl)[1,2, 4]triazolo[2,3-a] [1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385)) suggest that both A(1) and A(2a) receptors can increase the potency of nicorandil, while that of levcromakalim is increased only by A(2) receptors. Adenosine receptor activation did not affect the potency of pinacidil. Thus, adenosine receptor activation can increase the potency of some K(+) channel opening drugs to relax coronary arteries, but the details of the interaction with adenosine receptors depend on the particular drug.
Collapse
Affiliation(s)
- C S Davie
- Ion Channel Group, Department of Cell Physiology and Pharmacology, University of Leicester, PO Box 138, Leicester, UK
| | | | | |
Collapse
|