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Park WS, Ko JH, Ko EA, Son YK, Hong DH, Jung ID, Park YM, Choi TH, Kim N, Han J. The guanylyl cyclase activator YC-1 directly inhibits the voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells. J Pharmacol Sci 2010; 112:64-72. [PMID: 20093789 DOI: 10.1254/jphs.09228fp] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
We investigated the effects of YC-1, an activator of soluble guanylyl cyclase (sGC), on voltage-dependent K+ (Kv) channels in smooth muscle cells from freshly isolated rabbit coronary arteries by using the whole-cell patch clamp technique. YC-1 inhibited the Kv current in a dose-dependent fashion with an apparent K(d) of 9.67 microM. It accelerated the decay rate of Kv channel inactivation without altering the kinetics of current activation. The rate constants of association and dissociation for YC-1 were 0.36 +/- 0.01 microM(-1) x s(-1) and 3.44 +/- 0.22 s(-1), respectively. YC-1 did not have a significant effect on the steady-state activation and inactivation curves. The recovery time constant from inactivation was decreased in the presence of YC-1, and application of train pulses (1 or 2 Hz) caused a progressive increase in the YC-1 blockade, indicating that YC-1-induced inhibition of Kv currents is use-dependent. Pretreatment with Bay 41-2272 (also a sGC activator), ODQ (a sGC inhibitor), or Rp-8-Br-PET-cGMPs (a protein kinase G inhibitor) did not affect the basal Kv current and also did not significantly alter the inhibitory effect of YC-1. From these results, we suggest that YC-1 directly inhibits the Kv current independently of sGC activation and in a state-, time-, and use-dependent fashion.
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Affiliation(s)
- Won Sun Park
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, FIRST Mitochondrial Research Group, Biomarker Medical Research Center, Inje University, Korea
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Ko EA, Park WS, Firth AL, Kim N, Yuan JXJ, Han J. Pathophysiology of voltage-gated K+ channels in vascular smooth muscle cells: Modulation by protein kinases. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:95-101. [DOI: 10.1016/j.pbiomolbio.2009.10.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 10/07/2009] [Indexed: 10/20/2022]
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103
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Kim EY, Rhyu MR. Synergistic vasorelaxant and antihypertensive effects of Ligusticum wallichii and Angelica gigas. JOURNAL OF ETHNOPHARMACOLOGY 2010; 130:545-551. [PMID: 20669368 DOI: 10.1016/j.jep.2010.05.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
AIM OF THE STUDY The synergistic vasorelaxant and antihypertensive effects of Ligusticum wallichii and Angelica gigas were examined in isolated rat aorta rings and spontaneously hypertensive rats (SHRs). MATERIALS AND METHODS The ethanol extract of Ligusticum wallichii (LwEx) or Angelica gigas (AgEx) or their combinations at ratios Ligusticum wallichii:Angelica gigas = 1:1 (MxEx11), 1:3 (MxEx13), and 3:1 (and MxEx31), and their successive water soluble (LwDw, AgDw, MxDw11, MxDw13 and MxDw31) or n-butanol soluble fractions (LwBt, AgBt, MxBt11, MxBt13, and MxBt31) were examined for their vasorelaxant effects. In an antihypertensive study, LwEx, AgEx, or MxEx11 (100 mg/kg) was orally administered to SHRs, and the systolic, diastolic, and mean blood pressure were measured using the tail-cuff method before and 1, 3, 5, 7, and 24 h after oral administration. RESULTS Each of the ethanol extracts caused long-term relaxation in endothelium-intact or endothelium-denuded rat aorta preconstricted with norepinephrine (NE, 300 nM). All of the water phases of the ethanol extracts elicited an endothelium-dependent acute relaxation, and the water phase of MxDw11 (EC50 values: 1.08 mg/mL, P < 0.05) had the highest activity. MxDw11-induced acute relaxation was abolished by pretreatment with N(G)-nitro-L-arginine (10 microM), methylene blue (1.0 microM), or atropine (0.1 microM), indicating that the response to MxDw involves the enhancement of the nitric oxide-cGMP system. On the other hand, all of the butanol phases showed an endothelium-independent long-term relaxation, and MxBt11 (85 +/- 7% relaxation of NE-preconstricted active tone at 20 min after the addition, P < 0.05) displayed the highest activity. MxBt11-induced gradual relaxation was significantly attenuated by an inward rectifier potassium-channel inhibitor, but not by an ATP-sensitive or a large conductance Ca2+-activated potassium-channel blocker. Calcium concentration-dependent contraction curves in high-potassium, depolarizing medium were shifted significantly to the right and downward after incubation with MxBt11 (0.03, 0.1, and 0.3 mg/mL), implying that MxBt11 is also involved in the inhibition of extracellular calcium influx to vascular smooth muscle. MxEx11 (100 mg/kg) significantly reduced systolic blood pressure of SHRs at 3, 5, and 7 h after oral administration, but this effect was not induced by Ligusticum wallichii or Angelica gigas alone. CONCLUSIONS The combination of Ligusticum wallichii and Angelica gigas elicits a synergistic effect on vasorelaxation in isolated rat aortas and antihypertension in SHRs. The ratio of Ligusticum wallichii: Angelica gigas = 1:1 was the most effective of all combinations tested.
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Affiliation(s)
- Eun-Young Kim
- Food Function Research Division, Korea Food Research Institute, Bundang-gu, Seongnam-si, Gyeonggi-do 463-746, Republic of Korea
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Choi SS. Effect of pH Change on Vascular Smooth Muscle Contractility in Rat Superior Mesenteric Artery and Its Branches. THE KOREAN JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY 2010. [DOI: 10.5090/kjtcs.2010.43.4.345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Soo Seung Choi
- Department of Thoracic and Cardiovascular Surgery, Ewha Womans University School of Medicine
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105
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Türck G, Leonhard-Marek S. Potassium and insulin affect the contractility of abomasal smooth muscle. J Dairy Sci 2010; 93:3561-8. [DOI: 10.3168/jds.2009-2968] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 04/06/2010] [Indexed: 11/19/2022]
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Mukohda M, Yamawaki H, Okada M, Hara Y. Methylglyoxal enhances sodium nitroprusside-induced relaxation in rat aorta. J Pharmacol Sci 2010; 112:176-83. [PMID: 20168042 DOI: 10.1254/jphs.09219fp] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The concentration of methylglyoxal (MGO), a metabolite of glucose, increases in plasma of type II diabetic patients as well as in tissues of hypertensive rats. We have previously shown that MGO inhibited noradrenaline (NA)-induced smooth muscle contraction in rat aorta. However, the effect of MGO on relaxing responses in isolated blood vessel remains to be clarified. Thus, we examined if MGO affects acetylcholine (ACh)- or sodium nitroprusside (SNP)-induced vasodilation on NA (100 nM)-induced pre-contraction in rat thoracic aorta. Treatment of endothelium-intact aorta with MGO (420 microM, 30 min) did not change ACh (1 nM - 3 microM)-induced endothelium-dependent relaxation. In contrast, treatment of endothelium-denuded aorta with MGO shifted the concentration-response curve for SNP (0.1 - 300 nM) to the left. MGO increased reactive oxygen species (ROS) production in smooth muscle on analysis of protein carbonylation. Anti-oxidant agents such as tempol (10 microM), catalase (5000 U/mL), and nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methylester (100 microM) had no effect on MGO-induced enhancement of SNP-induced relaxation. However, iberiotoxin (100 nM), a large-conductance Ca(2+)-activated K(+) (BK(Ca))-channel inhibitor, significantly prevented the effect. The present study revealed that MGO enhanced SNP-induced relaxation in a ROS-independent manner via in part opening smooth muscle BK(Ca) channels.
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Affiliation(s)
- Masashi Mukohda
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Japan
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107
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Zhu Y, Chen L, Liu W, Wang W, Zhu D, Zhu Y. Hypoxia-induced 15-HETE enhances the constriction of internal carotid arteries by down-regulating potassium channels. J Neurol Sci 2010; 295:92-6. [PMID: 20483431 DOI: 10.1016/j.jns.2010.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 04/21/2010] [Accepted: 04/27/2010] [Indexed: 01/30/2023]
Abstract
Severe hypoxia induces the constriction of internal carotid arteries (ICA), which worsens ischemic stroke in the brain. A few metabolites are presumably involved in hypoxic vasoconstriction, however, less is known about how such molecules provoke this vasoconstriction. We have investigated the influence of 15-hydroxyeicosatetrienoic acid (15-HETE) produced by 15-lipoxygenase (15-LOX) on vasoconstriction during hypoxia. As showed in our results, 15-LOX level increases in ICA endothelia and smooth muscles. 15-HETE enhances the tension of ICA ring in a dose-dependent manner, as well as attenuates the activities and expression of voltage-gated potassium channels (Kv 1.5 and Kv 2.1). Therefore, the down-regulation of Kv channels by 15-HETE during hypoxia may weaken the repolarization of action potentials and causes a dominant influx of calcium ions to enhance smooth muscle tension and ICA constriction.
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Affiliation(s)
- Yanmei Zhu
- Department of Neurology, the Second Affiliated Hospital of Harbin Medical University, China
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Hirasawa Y, Hara M, Nugroho AE, Sugai M, Zaima K, Kawahara N, Goda Y, Awang K, Hadi AHA, Litaudon M, Morita H. Bisnicalaterines B and C, Atropisomeric Bisindole Alkaloids from Hunteria zeylanica, Showing Vasorelaxant Activity. J Org Chem 2010; 75:4218-23. [DOI: 10.1021/jo1006762] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yusuke Hirasawa
- Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Mayumi Hara
- Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Alfarius E. Nugroho
- Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Masatomo Sugai
- Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Kazumasa Zaima
- Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Nobuo Kawahara
- National Institute of Health Sciences, Kamiyoga 1-18-1, Setagaya-ku, Tokyo 158-8501, Japan
| | - Yukihiro Goda
- National Institute of Health Sciences, Kamiyoga 1-18-1, Setagaya-ku, Tokyo 158-8501, Japan
| | - Khalijah Awang
- Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - A. Hamid A. Hadi
- Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Marc Litaudon
- Institut de Chimie de la Substances Naturelles, Centre Nationale de la Recherches Scientifique, 91198, Gif-sur Yvette, Cedex, France
| | - Hiroshi Morita
- Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
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Waldkirch ES, Ückert S, Sigl K, Satzger I, Geismar U, Langnäse K, Richter K, Sohn M, Kuczyk MA, Hedlund P. Expression of cyclic AMP-dependent protein kinase isoforms in human cavernous arteries: functional significance and relation to phosphodiesterase type 4. J Sex Med 2010; 7:2104-2111. [PMID: 20487244 DOI: 10.1111/j.1743-6109.2010.01808.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION The cyclic adenosine monophosphate-dependent protein kinase (cAK) is considered a key protein in the control of smooth muscle tone in the cardiovascular system. There is evidence that erectile dysfunction might be linked to systemic vascular disorders and arterial insufficiency, subsequently resulting in structural changes in the penile tissue. The expression and significance of cAK in human cavernous arteries (HCA) have not been evaluated. AIMS To evaluate the expression of cAK isoforms in HCA and examine the role of cAK in the cyclic adenosine monophosphate (cAMP)- and cyclic guanosine monophosphate (cGMP)-mediated control of penile vascular smooth muscle. METHODS The expression and distribution of phosphodiesterase type 4 (PDE4) and cAK isoforms in sections of HCA were investigated by means of immunohistochemistry and Western blot analysis. The effects of the cAK inhibitor Rp-8-CPT-cAMPS on the relaxation of isolated preparations of HCA (diameter > 100 µm) induced by rolipram, sildenafil, tadalafil, and vardenafil were studied using the organ bath technique. MAIN OUTCOME MEASURES Investigate the expression of cAK in relation to α-actin and PDE4 in HCA and evaluate the effects of an inhibition of cAK on the relaxation induced by inhibitors of PDE4 and PDE5 of isolated penile arteries. RESULTS Immunosignals specific for cAKIα, IIα, and IIβ were observed within the wall of HCA. Double stainings revealed colocalization of cAK with α-actin and PDE4. The expression of cAK isoforms was confirmed by Western blot analysis. The reversion of tension induced by inhibitors of PDE4 and PDE5 of isolated penile vascular tissue were attenuated significantly by Rp-8-CPT-cAMPS. CONCLUSIONS Our results demonstrate the expression of cAK isoforms in the smooth musculature of HCA and its colocalization with PDE4. A significant role for cAK in the regulation mediated by cAMP and cGMP of vascular smooth muscle tone in HCA can also be assumed.
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Affiliation(s)
- Eginhard S Waldkirch
- Hannover Medical School-Division of Surgery, Department of Urology and Urological Oncology, Hannover, Germany
| | - Stefan Ückert
- Hannover Medical School-Division of Surgery, Department of Urology and Urological Oncology, Hannover, Germany.
| | | | - Imke Satzger
- Hannover Medical School-Department of Dermatology and Allergology, Hannover, Germany
| | | | - Kristina Langnäse
- Otto-von-Guericke-University, Faculty of Medicine-Institute for Biochemistry and Cell Biology, Magdeburg, Germany
| | - Karin Richter
- Otto-von-Guericke-University, Faculty of Medicine-Institute for Biochemistry and Cell Biology, Magdeburg, Germany
| | - Michael Sohn
- Frankfurter Diakonie-Kliniken, St. Markus Academic Hospital-Department of Urology, Frankfurt am Main, Germany
| | - Markus A Kuczyk
- Hannover Medical School-Division of Surgery, Department of Urology and Urological Oncology, Hannover, Germany
| | - Petter Hedlund
- University Vita Salute, Faculty of Medicine, San Raffaele Hospital-Department of Urology, Urological Research Institute, Milan, Italy
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Xu Z, Wang X, Dai Y, Kong L, Wang F, Xu H, Lu D, Song J, Hou Z. (+/-)-Praeruptorin A enantiomers exert distinct relaxant effects on isolated rat aorta rings dependent on endothelium and nitric oxide synthesis. Chem Biol Interact 2010; 186:239-46. [PMID: 20433815 DOI: 10.1016/j.cbi.2010.04.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Revised: 04/16/2010] [Accepted: 04/19/2010] [Indexed: 01/04/2023]
Abstract
Praeruptorin A is a coumarin compound naturally occurring in the roots of Peucedanum praeruptorum Dunn., a commonly used traditional Chinese medicine for the treatment of certain respiratory diseases and hypertension. Although previous studies indicated the relaxant effects of (+/-)-praeruptorin A on tracheal and arterial preparations, little is known about the functional characteristics of the enantiomers. In the present study, the two enantiomers were successfully isolated and identified by using a preparative Daicel Chiralpak AD-H column, and their relaxant effects on aorta rings were observed and compared. (+)-Praeruptorin A showed more potent relaxation than (-)-praeruptorin A against KCl- and phenylephrine-induced contraction of rat isolated aortic rings with intact endothelium. Removal of the endothelium remarkably reduced the relaxant effect of (+)-praeruptorin A but not that of (-)-praeruptorin A. Pretreatment of aortic rings with N(omega)-nitro-L-arginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) or methylene blue (MB, a soluble guanylyl cyclase inhibitor) resulted in similar changes of the relaxant effects of the two enantiomers to endothelium removal. Molecular docking studies also demonstrated that (+)-praeruptorin A was in more agreement to nitric oxide synthase pharmacophores than (-)-praeruptorin A. On the other hand, the two enantiomers of praeruptorin A could slightly attenuate the contraction of rat aortic rings induced by internal Ca(2+) release from sarcoplasmic reticulum (SR). These findings indicated that (+)-praeruptorin A and (-)-praeruptorin A exerted distinct relaxant effects on isolated rat aorta rings, which might be mainly attributed to nitric oxide synthesis catalyzed by endothelial nitric oxide synthase.
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Affiliation(s)
- Zhao Xu
- Department of Pharmacology of Chinese Materia Medica, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, Jiangsu, China
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111
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Biphasic effects of sodium danshensu on vessel function in isolated rat aorta. Acta Pharmacol Sin 2010; 31:421-8. [PMID: 20228827 DOI: 10.1038/aps.2010.24] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To investigate the effects of sodium danshensu on vessel function in isolated rat aortic ring. METHODS Thoracic aortae from normal rats were isolated and equilibrated in organ bath with Krebs-Henseleit buffer and ring tension was recorded. Effects of sodium danshensu on basal tonus of the vessel and its effects on vessel contraction and relaxation with or without endothelium were observed. RESULTS In thoracic arteries under basal tonus, sodium danshensu (0.3-3 g/L) produced a dose-dependent transient contraction. In phenylephrine-precontracted thoracic arteries with or without endothelium, low concentration (0.1-0.3 g/L) of sodium danshensu produced a weak contraction, while high concentrations (1-3 g/L) produced a pronounced vasodilator after a transient vasocontraction. Pre-incubation with sodium danshensu could inhibit vessel contraction induced by phenylephrine and potassium chloride in a concentration-dependent way. Sodium danshensu inhibited phenylephrine- and CaCl(2)-induced vasoconstriction in Ca(2+)-free medium. Pre-incubation with tetraethylammonium, a non-selective K(+) channel blocker, and apamin, a small-conductance calcium-activated K(+) channel blocker partially antagonized the relaxation response induced by sodium danshensu. However, iberiotoxin (big-conductance calcium-sensitive K(+) channel blocker), barium chloride (inward rectifier K(+) channel blocker), and glibencalmide (ATP-sensitive K(+) channel blocker) had no influence on the vasodilation effect of sodium danshensu. CONCLUSION Sodium danshensu showed a biphasic effects on vessel tension. While low dosage of sodium danshensu produced small contraction possibly through transient enhancement of Ca(2+) influx, high dosage produced significant vasodilation mainly through promoting the opening of non-selective K(+) channels and small-conductance calcium-sensitive K(+) channels in the vascular smooth muscle cells.
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112
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Abstract
Neuronal activity is communicated to the cerebral vasculature so that adequate perfusion of brain tissue is maintained at all levels of neuronal metabolism. An increase in neuronal activity is accompanied by vasodilation and an increase in local cerebral blood flow. This process, known as neurovascular coupling (NVC) or functional hyperemia, is essential for cerebral homeostasis and survival. Neuronal activity is encoded in astrocytic Ca(2+) signals that travel to astrocytic processes (;endfeet') encasing parenchymal arterioles within the brain. Astrocytic Ca(2+) signals cause the release of vasoactive substances to cause relaxation, and in some circumstances contraction, of the smooth muscle cells (SMCs) of parenchymal arterioles to modulate local cerebral blood flow. Activation of potassium channels in the SMCs has been proposed to mediate NVC. Here, the current state of knowledge of NVC and potassium channels in parenchymal arterioles is reviewed.
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Affiliation(s)
- Kathryn M Dunn
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, VT 05405, USA
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113
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Helle KB. The chromogranin A-derived peptides vasostatin-I and catestatin as regulatory peptides for cardiovascular functions. Cardiovasc Res 2010; 85:9-16. [PMID: 19640932 DOI: 10.1093/cvr/cvp266] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A range of inflammatory conditions is associated with pathologically high levels of circulating chromogranin A (CgA). This prohormone belongs to the family of uniquely acidic proteins co-stored and co-secreted with other hormones and peptides from the diffuse neuroendocrine system. Two highly conserved, CgA-derived peptides, vasostatin-I and catestatin, have been implicated as modulators of a wide range of cells and tissues, including those of the cardiovascular system. This review focuses on links between elevated circulating CgA and cardiovascular dysfunctions in inflammatory conditions in relation to potential beneficial effects of vasostatin-I and catestatin. Characteristic membrane-penetrating properties have been assigned to both peptides, and pertussis toxin sensitivity is shared by a number of their responses, notably in the vascular and cardiac endothelium. Pertussis toxin-sensitive, receptor-independent activation via heterotrimeric G proteins and Galphai/o subunits will be discussed as possible mechanisms for inhibitory effects of vasostatin-I and catestatin on vascular and cardiac responses. The accumulated evidence provides convincing support for vasostatin-I and catestatin as regulatory peptides for the cardiovascular system, converging on alleviation of significant dysfunctions as part of several inflammatory conditions.
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Affiliation(s)
- Karen B Helle
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, Bergen, Norway.
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114
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Addicott MA, Yang LL, Peiffer AM, Burnett LR, Burdette JH, Chen MY, Hayasaka S, Kraft RA, Maldjian JA, Laurienti PJ. The effect of daily caffeine use on cerebral blood flow: How much caffeine can we tolerate? Hum Brain Mapp 2009; 30:3102-14. [PMID: 19219847 PMCID: PMC2748160 DOI: 10.1002/hbm.20732] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 12/05/2008] [Accepted: 12/15/2008] [Indexed: 12/23/2022] Open
Abstract
Caffeine is a commonly used neurostimulant that also produces cerebral vasoconstriction by antagonizing adenosine receptors. Chronic caffeine use results in an adaptation of the vascular adenosine receptor system presumably to compensate for the vasoconstrictive effects of caffeine. We investigated the effects of caffeine on cerebral blood flow (CBF) in increasing levels of chronic caffeine use. Low (mean = 45 mg/day), moderate (mean = 405 mg/day), and high (mean = 950 mg/day) caffeine users underwent quantitative perfusion magnetic resonance imaging on four separate occasions: twice in a caffeine abstinent state (abstained state) and twice in a caffeinated state following their normal caffeine use (native state). In each state, there were two drug conditions: participants received either caffeine (250 mg) or placebo. Gray matter CBF was tested with repeated-measures analysis of variance using caffeine use as a between-subjects factor, and correlational analyses were conducted between CBF and caffeine use. Caffeine reduced CBF by an average of 27% across both caffeine states. In the abstained placebo condition, moderate and high users had similarly greater CBF than low users; but in the native placebo condition, the high users had a trend towards less CBF than the low and moderate users. Our results suggest a limited ability of the cerebrovascular adenosine system to compensate for high amounts of daily caffeine use.
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Affiliation(s)
- Merideth A. Addicott
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Lucie L. Yang
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Ann M. Peiffer
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Luke R. Burnett
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Jonathan H. Burdette
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Michael Y. Chen
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Satoru Hayasaka
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
- Department of Biostatistical Sciences, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Robert A. Kraft
- Department of Biomedical Engineering, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Joseph A. Maldjian
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
| | - Paul J. Laurienti
- Department of Radiology, Wake Forest University School of Medicine, Winston‐Salem, North Carolina
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Brueggemann LI, Mackie AR, Mani BK, Cribbs LL, Byron KL. Differential effects of selective cyclooxygenase-2 inhibitors on vascular smooth muscle ion channels may account for differences in cardiovascular risk profiles. Mol Pharmacol 2009; 76:1053-61. [PMID: 19605525 DOI: 10.1124/mol.109.057844] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Celecoxib, rofecoxib, and diclofenac are clinically used cyclooxygenase-2 (COX-2) inhibitors, which have been under intense scrutiny because long-term rofecoxib (Vioxx; Merck, Whitehouse Station, NJ) treatment was found to increase the risk of adverse cardiovascular events. A differential risk profile for these drugs has emerged, but the underlying mechanisms have not been fully elucidated. We investigated the effects of celecoxib, rofecoxib, and diclofenac on ionic currents and calcium signaling in vascular smooth muscle cells (VSMCs) using patch-clamp techniques and fura-2 fluorescence and on arterial constriction using pressure myography. Celecoxib, but not rofecoxib or diclofenac, dramatically enhanced KCNQ (K(v)7) potassium currents and suppressed L-type voltage-sensitive calcium currents in A7r5 rat aortic smooth muscle cells (native KCNQ currents or overexpressed human KCNQ5 currents) and freshly isolated rat mesenteric artery myocytes. The effects of celecoxib were concentration-dependent within the therapeutic concentration range, and were reversed on washout. Celecoxib, but not rofecoxib, also inhibited calcium responses to vasopressin in A7r5 cells and dilated intact or endothelium-denuded rat mesenteric arteries. A celecoxib analog, 2,5-dimethyl-celecoxib, which does not inhibit COX-2, mimicked celecoxib in its enhancement of vascular KCNQ5 currents, suppression of L-type calcium currents, and vasodilation. We conclude that celecoxib inhibits calcium responses in VSMCs by enhancing KCNQ5 currents and suppressing L-type calcium currents, which ultimately reduces vascular tone. These effects are independent of its COX-2 inhibitory actions and may explain the differential risk of cardiovascular events in patients taking different drugs of this class.
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116
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Straub SV, Girouard H, Doetsch PE, Hannah RM, Wilkerson MK, Nelson MT. Regulation of intracerebral arteriolar tone by K(v) channels: effects of glucose and PKC. Am J Physiol Cell Physiol 2009; 297:C788-96. [PMID: 19605735 DOI: 10.1152/ajpcell.00148.2009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Voltage-gated potassium (K(v)) channels in vascular smooth muscle cells (VSMC) are critical regulators of membrane potential and vascular tone. These channels exert a hyperpolarizing influence to counteract the depolarizing effects of intraluminal pressure and vasoconstrictors. However, the contribution of K(v) channel activity to the functional regulation of cerebral (parenchymal) arterioles within the brain is not known. Thus K(v) channel properties in parenchymal arteriolar SMCs were characterized. Isolated, pressurized parenchymal arterioles and arterioles in cortical brain slices exhibited robust constriction in the presence of the K(v) channel inhibitor 4-aminopyridine (4-AP). 4-AP also decreased the amplitude of K(v) currents recorded from SMCs. The steady-state activation and inactivation properties of K(v) currents suggested that these channels are composed of K(v)1.2 and 1.5 subunits, which was confirmed by RT-PCR. K(v) channels can be regulated by extracellular glucose, which may be involved in the functional hyperemic response in the brain. Thus the effects of glucose on K(v) channel activity and arteriolar function were investigated. Elevation of glucose from 4 to 14 mM significantly decreased the peak K(v) current amplitude and constricted arterioles. Arteriolar constriction was prevented by inhibition of protein kinase C (PKC), consistent with previous studies showing enhanced PKC activity in the presence of elevated glucose. In cortical brain slices, the dilation generated by neuronal activity induced by electrical field stimulation was decreased by 54% in 14 mM glucose when compared with the dilation in 4 mM glucose. In anesthetized mice the whisker stimulation-induced increase in local cerebral blood flow was also significantly decreased in 14 mM glucose, and this effect was similarly prevented by PKC inhibition. These findings point to a critical role for K(v) channels in the regulation of intracerebral arteriolar function and suggest that changes in perivascular glucose levels could directly alter vascular diameter resulting in a modulation of local cerebral blood flow.
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Affiliation(s)
- Stephen V Straub
- Dept. of Pharmacology, University of Vermont, Burlington, VT 05405, USA
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117
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Lund CO, Nilas L, Dalsgaard T, Pedersen SH, Ottesen B. Acute effects of tibolone on cerebral vascular reactivityin vitro. Climacteric 2009. [DOI: 10.1080/cmt.6.3.228.237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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118
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Effects of taurine on contractions of the porcine coronary artery. Pharmacol Rep 2009; 61:681-9. [DOI: 10.1016/s1734-1140(09)70120-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 07/02/2009] [Indexed: 11/24/2022]
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119
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Dua AK, Dua N, Murrant CL. Skeletal muscle contraction-induced vasodilator complement production is dependent on stimulus and contraction frequency. Am J Physiol Heart Circ Physiol 2009; 297:H433-42. [DOI: 10.1152/ajpheart.00216.2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To test the hypothesis that the vasodilator complement that produces arteriolar vasodilation during muscle contraction depends on both stimulus and contraction frequency, we stimulated four to five skeletal muscle fibers in the anesthetized hamster cremaster preparation in situ and measured the change in diameter of arterioles at a site of overlap with the stimulated muscle fibers. Diameter was measured before, during, and after 2 min of skeletal muscle contraction stimulated over a range of stimulus frequencies [4, 20, and 40 Hz; 15 contractions/min (cpm), 250 ms train duration] and a range of contraction frequencies (6, 15, and 60 cpm; 20 Hz stimulus frequency, 250 ms train duration). Muscle fibers were stimulated in the absence and presence of an inhibitor of adenosine receptors [10−6 M xanthine amine congener (XAC)], an ATP-dependent potassium (K+) channel inhibitor (10−5 M glibenclamide), an inhibitor of a source of K+ by inhibition of voltage-dependent K+ channels [3 × 10−4 M 3,4-diaminopyridine (DAP)], and an inhibitor of nitric oxide synthase [10−6 M NG-nitro-l-arginine methyl ester (l-NAME) + 10−7 S-nitroso- N-acetylpenicillamine (a nitric oxide donor)]. l-NAME inhibited the dilations at all stimulus frequencies and contraction frequencies except 60 cpm. XAC inhibited the dilations at all contraction frequencies and stimulus frequencies except 40 Hz. Glibenclamide inhibited all dilations at all stimulus and contraction frequencies, and DAP did not inhibit dilations at any stimulus frequencies while attenuating dilation at a contraction frequency of 60 cpm only. Our data show that the complement of dilators responsible for the vasodilations induced by skeletal muscle contraction differed depending on the stimulus and contraction frequency; therefore, both are important determinants of the dilators involved in the processes of arteriolar vasodilation associated with active hyperemia.
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120
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Stadnicka A, Contney SJ, Moreno C, Weihrauch D, Bosnjak ZJ, Roman RJ, Stekiel TA. Mechanism of differential cardiovascular response to propofol in Dahl salt-sensitive, Brown Norway, and chromosome 13-substituted consomic rat strains: role of large conductance Ca2+ and voltage-activated potassium channels. J Pharmacol Exp Ther 2009; 330:727-35. [PMID: 19541907 DOI: 10.1124/jpet.109.154104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Cardiovascular sensitivity to general anesthetics is highly variable among individuals in both human and animal models, but little is known about the genetic determinants of drug response to anesthetics. Recently, we reported that propofol (2,6-diisopropylphenol) causes circulatory instability in Dahl salt-sensitive SS/JRHsdMcwi (SS) rats but not in Brown Norway BN/NHsdMcwi (BN) rats and that these effects are related to genes on chromosome 13. Based on the hypothesis that propofol does target mesenteric circulation, we investigated propofol modulation of mesenteric arterial smooth muscle cells (MASMC) in SS and BN rats. The role of chromosome 13 was tested using SS-13(BN)/Mcwi and BN-13(SS)/Mcwi consomic strains with chromosome 13 substitution. Propofol (5 microM) produced a greater in situ hyperpolarization of MASMC membrane potential in SS than BN rats, and this effect was abrogated by iberiotoxin, a voltage-activated potassium (BK) channel blocker. In inside-out patches, the BK channel number, P(o), and apparent Ca(2+) sensitivity, and propofol sensitivity all were significantly greater in MASMC of SS rats. The density of whole-cell BK current was increased by propofol more in SS than BN myocytes. Immunolabeling confirmed higher expression of BK alpha subunit in MASMC of SS rats. Furthermore, the hyperpolarization produced by propofol, the BK channel properties, and propofol sensitivity were modified in MASMC of SS-13(BN)/Mcwi and BN-13(SS)/Mcwi strains toward the values observed in the background SS and BN strains. We conclude that differential function and expression of BK channels, resulting from genetic variation within chromosome 13, contribute to the enhanced propofol sensitivity in SS and BN-13(SS)/Mcwi versus BN and SS-13(BN)/Mcwi strains.
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Affiliation(s)
- Anna Stadnicka
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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121
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Raveaud S, Mezin P, Lavanchy N, Starcher B, Mecham RP, Verdetti J, Faury G. Effects of chronic treatment with a low dose of nicorandil on the function of the rat aorta during ageing. Clin Exp Pharmacol Physiol 2009; 36:988-94. [PMID: 19473347 DOI: 10.1111/j.1440-1681.2009.05174.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. It is known that ATP-sensitive potassium (K(ATP)) channels regulate the membrane potential of smooth muscle cells and vascular tone. Because their activity is altered during ageing, many pharmacological treatments aimed at improving K(ATP) channel and cardiovascular functions have been evaluated. Nicorandil, a K(ATP) channel opener, nitric oxide (NO) donor and anti-oxidant, induces vasodilation, decreases blood pressure and exhibits cardioprotection in ageing, as well as after ischaemia-reperfusion. 2. In the present study, using tension myography and biochemical and histological techniques, we investigated the effects of chronic (2 months) low-dose nicorandil (0.1 mg/kg per day) treatment on the function of rat aorta during ageing (in 4-, 12- and 24-month old rats). 3. The results showed that chronic nicorandil treatment significantly improves mechanical relaxation and noradrenaline-induced vasoconstriction in aged rats. At all ages, the nicorandil-induced vasodilation was primarily mediated by its NO donor group. Nicorandil treatment resulted in an additional 0.5-1 elastic lamella in the aorta and decreased total protein, collagen and elastin content in the aortic wall at all ages. However, in 4-month-old rats, nicorandil significantly increased the elastin : total protein ratio by 19%. 4. In contrast with results of previous studies that used high doses of nicorandil (i.e. 60 mg/kg per day), low-dose nicorandil treatment in the present study did not lead to a progressive desensitization to nicorandil and may be beneficial in improving arterial function in ageing or cardiovascular diseases.
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Affiliation(s)
- Stéphanie Raveaud
- Laboratory of Vascular Physiopathologies: Cellular Interactions, Signalling and Ageing, Joseph Fourier University, Grenoble, F-38041, France
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122
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Mochalov SV, Kalenchuk VU, Gainullina DK, Vorotnikov AV, Tarasova OS. The contribution of protein kinase C and rho-kinase to the regulation of receptor-dependent contraction of arteries decreases with age independently of sympathetic innervation. Biophysics (Nagoya-shi) 2009. [DOI: 10.1134/s0006350908060298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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123
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Montes FR, Cabrera M, Delgadillo A, Salgar C, Echeverri D. The role of potassium channels in the vasodilatory effect of caffeine in human internal mammary arteries. Vascul Pharmacol 2009; 50:132-6. [DOI: 10.1016/j.vph.2008.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 11/11/2008] [Accepted: 11/14/2008] [Indexed: 11/27/2022]
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124
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Chen GP, Ye Y, Li L, Yang Y, Qian AB, Hu SJ. Endothelium-independent vasorelaxant effect of sodium ferulate on rat thoracic aorta. Life Sci 2009; 84:81-8. [PMID: 19038273 DOI: 10.1016/j.lfs.2008.11.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 08/29/2008] [Accepted: 11/05/2008] [Indexed: 12/18/2022]
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125
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Mukohda M, Yamawaki H, Nomura H, Okada M, Hara Y. Methylglyoxal Inhibits Smooth Muscle Contraction in Isolated Blood Vessels. J Pharmacol Sci 2009; 109:305-10. [DOI: 10.1254/jphs.08300fp] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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126
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Functional and molecular consequences of ionizing irradiation on large conductance Ca2+-activated K+ channels in rat aortic smooth muscle cells. Life Sci 2009; 84:164-71. [DOI: 10.1016/j.lfs.2008.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 10/27/2008] [Accepted: 11/10/2008] [Indexed: 11/23/2022]
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127
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Hyvelin JM, Gautier M, Lemaire MC, Bonnet P, Eder V. Adaptative modifications of right coronary myocytes voltage-gated K+ currents in rat with hypoxic pulmonary hypertension. Pflugers Arch 2008; 457:721-30. [PMID: 18633640 DOI: 10.1007/s00424-008-0546-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 06/13/2008] [Indexed: 12/19/2022]
Abstract
Chronic hypoxia (CH)-induced pulmonary hypertension (PHT) is well known to alter K+ channels in pulmonary myocytes. PHT induces right ventricle hypertrophy that increases oxygen demand; however, coronary blood flow and K+ channel adaptations of coronary myocytes during PHT remain unknown. We determined whether CH and PHT altered K+ currents and coronary reactivity and what impact they might have on right myocardial perfusion. Right ventricle perfusion, as attested by microspheres, was redistributed toward hypertrophied right ventricle [RV/LV (%)=0.59+/-0.07% in CH rats vs. 0.29+/-0.03 in control rats, P<0.05]. Whole-cell patch clamping showed a reduction of global outward current in hypoxic right coronary artery myocytes (H-RCA), whereas hypoxic left coronary artery myocytes exhibited an increase. K+ channel blockers revealed that a 4-aminopyridine (4AP)-sensitive current (Kv current) was decreased in H-RCA (14.3+/-1.1 vs. 23.4+/-2.5 pA/pF at 60 mV in control RCA, P<0.05) and increased in hypoxic left coronary artery myocytes (H-LCA; 26.4+/-3.8 vs. 11.8+/-1.6 pA/pF at 60 mV in control LCA, P<0.05). Constriction to 4AP was decreased in H-RCA when compared to normoxic control and increased in H-LCA when compared to LCA. Finally, we observed that the expression of Kv1.2 and Kv1.5 were lower in H-RCA than that in H-LCA. This study reveals that CH differentially regulates Kv channels in coronary myocytes. Hypoxia decreases Kv currents and therefore reduces vasoreactivity that contributes to an adaptative response leading to right hypertrophied ventricle perfusion enhancement at rest.
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Affiliation(s)
- Jean-Marc Hyvelin
- Laboratoire de Physiopathologie de la Paroi Artérielle, EA 3852, IFR 135, UFR Médecine, Université François Rabelais, 10 Bld Tonnellé, BP 3223, 37032, Tours Cedex, France.
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128
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Kajioka S, Nakayama S, Asano H, Seki N, Naito S, Brading AF. Levcromakalim and MgGDP activate small conductance ATP-sensitive K+ channels of K+ channel pore 6.1/sulfonylurea receptor 2A in pig detrusor smooth muscle cells: uncoupling of cAMP signal pathways. J Pharmacol Exp Ther 2008; 327:114-23. [PMID: 18596222 DOI: 10.1124/jpet.108.140269] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pharmacological studies have suggested the existence of ATP-sensitive K(+) (K(ATP)) channel as a therapeutic target in urinary bladders; however, electrical properties have not yet been shown. Patch-clamp techniques were applied to investigate the properties of K(ATP) channels in pig detrusor cells. In whole-cell configuration, levcromakalim, a K(ATP) channel opener, induced a long-lasting outward current in a concentration-dependent manner. The current-voltage curve of the levcromakalim-induced membrane current intersected at approximately -80 mV. This current was abolished by glibenclamide. Intracellular application of 0.1 mM GDP significantly enhanced the levcromakalim-induced membrane current, whereas cAMP did not. Furthermore, neurotransmitters related to cAMP signaling, such as calcitonin gene-related peptide, vasointestinal peptide, adenosine, and somatostatin, had little effect on the membrane current. In cell-attached configuration, levcromakalim activated K(+) channels with a unitary conductance of approximately 12 pS. When the patch configuration was changed to inside-out mode, the K(+) channel activity ran down. Subsequent application of 1 mM GDP reactivated the channels. The openings of the approximately 12 pS K(+) channels in the presence of 1 mM GDP was suppressed by ATP and glibenclamide. In reverse transcription-polymerase chain reaction, K(+) channel pore 6.1 and sulfonylurea receptor (SUR)2A were predominant in pig detrusor cells. The 12 pS K(+) channel activated by levcromakalim in pig detrusor smooth muscle cells is a K(ATP) channel. The predominant expression of SUR2A can account for the lack of effect of neurotransmitters related to cAMP.
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129
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Abstract
Exercise is the most important physiological stimulus for increased myocardial oxygen demand. The requirement of exercising muscle for increased blood flow necessitates an increase in cardiac output that results in increases in the three main determinants of myocardial oxygen demand: heart rate, myocardial contractility, and ventricular work. The approximately sixfold increase in oxygen demands of the left ventricle during heavy exercise is met principally by augmenting coronary blood flow (∼5-fold), as hemoglobin concentration and oxygen extraction (which is already 70–80% at rest) increase only modestly in most species. In contrast, in the right ventricle, oxygen extraction is lower at rest and increases substantially during exercise, similar to skeletal muscle, suggesting fundamental differences in blood flow regulation between these two cardiac chambers. The increase in heart rate also increases the relative time spent in systole, thereby increasing the net extravascular compressive forces acting on the microvasculature within the wall of the left ventricle, in particular in its subendocardial layers. Hence, appropriate adjustment of coronary vascular resistance is critical for the cardiac response to exercise. Coronary resistance vessel tone results from the culmination of myriad vasodilator and vasoconstrictors influences, including neurohormones and endothelial and myocardial factors. Unraveling of the integrative mechanisms controlling coronary vasodilation in response to exercise has been difficult, in part due to the redundancies in coronary vasomotor control and differences between animal species. Exercise training is associated with adaptations in the coronary microvasculature including increased arteriolar densities and/or diameters, which provide a morphometric basis for the observed increase in peak coronary blood flow rates in exercise-trained animals. In larger animals trained by treadmill exercise, the formation of new capillaries maintains capillary density at a level commensurate with the degree of exercise-induced physiological myocardial hypertrophy. Nevertheless, training alters the distribution of coronary vascular resistance so that more capillaries are recruited, resulting in an increase in the permeability-surface area product without a change in capillary numerical density. Maintenance of α- and ß-adrenergic tone in the presence of lower circulating catecholamine levels appears to be due to increased receptor responsiveness to adrenergic stimulation. Exercise training also alters local control of coronary resistance vessels. Thus arterioles exhibit increased myogenic tone, likely due to a calcium-dependent protein kinase C signaling-mediated alteration in voltage-gated calcium channel activity in response to stretch. Conversely, training augments endothelium-dependent vasodilation throughout the coronary microcirculation. This enhanced responsiveness appears to result principally from an increased expression of nitric oxide (NO) synthase. Finally, physical conditioning decreases extravascular compressive forces at rest and at comparable levels of exercise, mainly because of a decrease in heart rate. Impedance to coronary inflow due to an epicardial coronary artery stenosis results in marked redistribution of myocardial blood flow during exercise away from the subendocardium towards the subepicardium. However, in contrast to the traditional view that myocardial ischemia causes maximal microvascular dilation, more recent studies have shown that the coronary microvessels retain some degree of vasodilator reserve during exercise-induced ischemia and remain responsive to vasoconstrictor stimuli. These observations have required reassessment of the principal sites of resistance to blood flow in the microcirculation. A significant fraction of resistance is located in small arteries that are outside the metabolic control of the myocardium but are sensitive to shear and nitrovasodilators. The coronary collateral system embodies a dynamic network of interarterial vessels that can undergo both long- and short-term adjustments that can modulate blood flow to the dependent myocardium. Long-term adjustments including recruitment and growth of collateral vessels in response to arterial occlusion are time dependent and determine the maximum blood flow rates available to the collateral-dependent vascular bed during exercise. Rapid short-term adjustments result from active vasomotor activity of the collateral vessels. Mature coronary collateral vessels are responsive to vasodilators such as nitroglycerin and atrial natriuretic peptide, and to vasoconstrictors such as vasopressin, angiotensin II, and the platelet products serotonin and thromboxane A2. During exercise, ß-adrenergic activity and endothelium-derived NO and prostanoids exert vasodilator influences on coronary collateral vessels. Importantly, alterations in collateral vasomotor tone, e.g., by exogenous vasopressin, inhibition of endogenous NO or prostanoid production, or increasing local adenosine production can modify collateral conductance, thereby influencing the blood supply to the dependent myocardium. In addition, vasomotor activity in the resistance vessels of the collateral perfused vascular bed can influence the volume and distribution of blood flow within the collateral zone. Finally, there is evidence that vasomotor control of resistance vessels in the normally perfused regions of collateralized hearts is altered, indicating that the vascular adaptations in hearts with a flow-limiting coronary obstruction occur at a global as well as a regional level. Exercise training does not stimulate growth of coronary collateral vessels in the normal heart. However, if exercise produces ischemia, which would be absent or minimal under resting conditions, there is evidence that collateral growth can be enhanced. In addition to ischemia, the pressure gradient between vascular beds, which is a determinant of the flow rate and therefore the shear stress on the collateral vessel endothelium, may also be important in stimulating growth of collateral vessels.
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130
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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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131
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Hernández A, Sola MA, Domínguez B, Rochera MI, Bascuñana P, Gancedo V. [Is morphine still the analgesic of choice in acute myocardial infarction?]. REVISTA ESPANOLA DE ANESTESIOLOGIA Y REANIMACION 2008; 55:32-39. [PMID: 18333384 DOI: 10.1016/s0034-9356(08)70495-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Chest pain is the most common symptom of patients who present with ischemic heart disease. Morphine has traditionally been the drug of choice for managing chest pain in acute coronary syndrome (ACS) due to its high analgesic potency, though its physiological effects are poorly understood. Routinely used for managing chest pain, morphine is recommended in the 2002 guidelines of the American College of Cardiology/American Heart Association. This recommendation, however, is not based on a high level of scientific evidence but on expert opinion. Studies have found both for and against the use of morphine in ACS, suggesting that its benefits are perhaps not altogether clear. This review examines the pathophysiological effects of morphine and their cardiac implications, with special attention to a possible negative effect on ACS. We reviewed articles in the MEDLINE database from 1982 to 2006.
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Affiliation(s)
- A Hernández
- Servicio de Anestesiología y Reanimación, Hospital General Universitario Vall d'Hebron, Barcelona.
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132
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Lee SJ, Baik SW, Cho HR, Kim WS, Baek SH. Effects of Propofol on Arginine Vasopressin-induced Contraction in Isolated Human Gastroepiploic Artery. Korean J Anesthesiol 2008. [DOI: 10.4097/kjae.2008.54.6.662] [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] Open
Affiliation(s)
- Sung-Jin Lee
- Department of Anesthesiology and Pain Medicine, Pusan National University College of Medicine, Busan, Korea
| | - Seong-Wan Baik
- Department of Anesthesiology and Pain Medicine, Pusan National University College of Medicine, Busan, Korea
| | - Hyeok-Rae Cho
- Department of Anesthesiology and Pain Medicine, Pusan National University College of Medicine, Busan, Korea
| | - Won-Sung Kim
- Department of Anesthesiology and Pain Medicine, Pusan National University College of Medicine, Busan, Korea
| | - Seung-Hoon Baek
- Department of Anesthesiology and Pain Medicine, Pusan National University College of Medicine, Busan, Korea
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133
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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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134
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Rocha ML, Bendhack LM. Effects of K+ channel modulators on oscillatory contractions in sinoaortic denervated rat aortas. Biol Pharm Bull 2007; 30:2098-104. [PMID: 17978483 DOI: 10.1248/bpb.30.2098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sinoaortic denervated (SAD) rats present arterial pressure lability without sustained hypertension. We investigated the relation between sinoaortic denervation and the occurrence of oscillatory contractions in SAD rat aortas, as well as the effect of various K(+) channel modulators on these oscillations. Aortas were removed and concentration-effect curves to phenylephrine (0.01 to 10 muM) were constructed in arteries from SAD and Sham-operated rats in order to verify the occurrence of oscillations. We also evaluated the effects of various K(+) channel modulators on these oscillations. Only SAD rat aortas exhibited oscillatory contractions. Tetraethylammonium increased the frequency (28.5+/-3.5 to 41.5+/-4.5 counts/5 min) and amplitude (0.435+/-0.07 to 0.630+/-0.09 g) of the oscillations. Apamin and 4-aminopyridine did not alter the oscillations. Barium chloride converted the oscillatory contractions to a tonic contraction. Pinacidil rapidly blocked the oscillatory contractions and glibenclamide evoked reduction in amplitude from 0.410+/-0.07 to 0.180+/-0.06 g. Iberiotoxin increased the frequency of oscillatory contractions (from 28.0+/-3.5 to 51.5+/-7.5 counts/5 min) but decreased the amplitude (from 0.410+/-0.08 to 0.195+/-0.2 g). Our results demonstrate that SAD rat aortas exhibit oscillatory contractions and K(+) channels, mainly K(ATP) and BK(Ca), play a dominant role in these oscillations.
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Affiliation(s)
- Matheus Lavorenti Rocha
- Department of Pharmacology, Faculty of Medicine of Ribeirão Preto, University of Sao Paulo, Ribeirão Preto, SP, Brazil
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135
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Lee PY, Chen W, Liu IM, Cheng JT. VASODILATATION INDUCED BY SINOMENINE LOWERS BLOOD PRESSURE IN SPONTANEOUSLY HYPERTENSIVE RATS. Clin Exp Pharmacol Physiol 2007; 34:979-84. [PMID: 17714082 DOI: 10.1111/j.1440-1681.2007.04668.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. Sinomenine is an alkaloid with a wide range of pharmacological actions. In the present study, we investigated the effect of sinomenine on blood pressure and its possible mechanisms of action. 2. Spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were given intraperitoneal injections of sinomenine. At 30 min, 2.5-10 mg/kg sinomenine decreased systolic blood pressure (SBP) in a dose-dependent manner in SHR, but had no effect on the SBP in WKY rats. 3. The vascular effect of sinomenine was then examined in aortic rings isolated from Wistar rats. Sinomenine (0.1-10 micromol/L) produced concentration-dependent relaxation in aortic rings precontracted with phenylephrine (10 nmol/L) or KCl (40 mmol/L). Glibenclamide (1-100 micromol/L), a specific inhibitor of ATP-sensitive K(+) channels attenuated the sinomenine-induced relaxation, but this effect was not observed when inhibitors of other types of K(+) channels were used. 4. We further investigated the effects of sinomenine on changes in intracellular Ca(2+) concentrations ([Ca(2+)](i)) in cultured aortic smooth muscle (A7r5) cells by using the Ca(2+)-sensitive dye fura-2 as an indicator. Sinomenine, over the concentration range 0.1-10 micromol/L, decreased the increases in [Ca(2+)](i) elicited by phenylephrine (1 micromol/L) or KCl (40 mmol/L) in a concentration-dependent manner. Glibenclamide (1-100 micromol/L) abolished the effects of sinomenine. 5. In conclusion, sinomenine causes vascular relaxation by opening ATP-sensitive K(+) channels, thus decreasing [Ca(2+)](i).
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Affiliation(s)
- Ping-Ying Lee
- Division of Cardiology, Department of Internal Medicine, Mackay Memorial Hospital, Mackay Medicine, Nursing and Management College, Taipei, Taiwan
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136
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Hercule HC, Salanova B, Essin K, Honeck H, Falck JR, Sausbier M, Ruth P, Schunck WH, Luft FC, Gollasch M. The vasodilator 17,18-epoxyeicosatetraenoic acid targets the pore-forming BK alpha channel subunit in rodents. Exp Physiol 2007; 92:1067-76. [PMID: 17675416 DOI: 10.1113/expphysiol.2007.038166] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
17,18-Epoxyeicosatetraenoic acid (17,18-EETeTr) stimulates vascular large-conductance K(+) (BK) channels. BK channels are composed of the pore-forming BK alpha and auxiliary BK beta1 subunits that confer an increased sensitivity for changes in membrane potential and calcium to BK channels. Ryanodine-sensitive calcium-release channels (RyR3) in the sarcoplasmic reticulum (SR) control the process. To elucidate the mechanism of BK channel activation, we performed whole-cell and perforated-patch clamp experiments in freshly isolated cerebral and mesenteric artery vascular smooth muscle cells (VSMC) from Sprague-Dawley rats, BK beta1 gene-deficient (-/-), BK alpha (-/-), RyR3 (-/-) and wild-type mice. The 17,18-EETeTr (100 nm) increased tetraethylammonium (1 mm)-sensitive outward K(+) currents in VSMC from wild-type rats and wild-type mice. The effects were not inhibited by the epoxyeicosatrienoic acid (EET) antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (10 mum). BK channel currents were increased 3.5-fold in VSMC from BK beta1 (-/-) mice, whereas a 2.9-fold stimulation was observed in VSMC from RyR3 (-/-) mice (at membrane voltage 60 mV). The effects were similar compared with those observed in cells from wild-type mice. The BK current increase was neither influenced by strong internal calcium buffering (Ca(2)(+), 100 nm), nor by external calcium influx. The 17,18-EETeTr did not induce outward currents in VSMC BK alpha (-/-) cells. We next tested the vasodilator effects of 17,18-EETeTr on isolated arteries of BK alpha-deficient mice. Vasodilatation was largely inhibited in cerebral and mesenteric arteries isolated from BK alpha (-/-) mice compared with that observed in wild-type and BK beta1 (-/-) arteries. We conclude that 17,18-EETeTr represents an endogenous BK channel agonist and vasodilator. Since 17,18-EETeTr is active in small arteries lacking BK beta1, the data further suggest that BK alpha represents the molecular target for the principal action of 17,18-EETeTr. Finally, the action of 17,18-EETeTr is not mediated by changes of the internal global calcium concentration or local SR calcium release events.
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Affiliation(s)
- Hantz C Hercule
- Nephrology/Hypertension Division, Franz Volhard Clinic, HELIOS Klinikum-Berlin, Campus Buch, Berlin, Germany
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137
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Haynes JM. beta(2) and beta(3)-adrenoceptor inhibition of alpha(1)-adrenoceptor-stimulated Ca(2+) elevation in human cultured prostatic stromal cells. Eur J Pharmacol 2007; 570:18-26. [PMID: 17617401 DOI: 10.1016/j.ejphar.2007.05.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 05/18/2007] [Accepted: 05/22/2007] [Indexed: 11/15/2022]
Abstract
Prostatic beta-adrenoceptors inhibit alpha(1)-adrenoceptor-stimulated contractility. This study examines the effects of beta-adrenoceptor stimulation upon phenylephrine-induced elevations of intracellular Ca(2+)([Ca(2+)](i)) in human cultured prostatic stromal cells, and contractility of human prostatic tissue. Human cultured prostatic stromal cells were used for [(3)H]-cAMP accumulation studies or were loaded with 5-oxazolecarboxylic acid, 2-(6-(bis(2-((acetyloxy)methoxy)-2-oxoethyl)amino)-5-(2-(2-(bis(2-((acetyloxy)methoxy)-2-oxoethyl)amino)-5-methylphenoxy)ethoxy)-2-benzofuranyl)-, (acetyloxy)methyl ester (FURA-2AM, 10 microM) for Ca(2+) imaging studies. The beta-adrenoceptor agonist isoprenaline increased the accumulation of [(3)H]-cAMP (pEC(50)+/-S.E.M. 6.58+/-0.11) in human cultured prostatic stromal cells, an effect antagonized by the beta(2)-adrenoceptor antagonist (+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol (ICI 118,551), but not by the beta(1)-adrenoceptor antagonist, atenolol. Isoprenaline (3 microM), the adenylyl cyclase activator, forskolin (20 microM) and the phosphodiesterase-4 inhibitor, rolipram (10 microM) inhibited the elevation of [Ca(2+)](i) elicited by phenylephrine (20 microM). The effect of isoprenaline could be blocked by ICI 118,551 (100 nM), the adenylyl cyclase inhibitor cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine (MDL 12,330A, 20 microM) and the K(Ca) channel blocker, iberiotoxin (100 nM), but not by atenolol (1 microM) or the K(ATP) channel blocker, glibenclamide (3 microM). Agonists selective for beta(1)-(xamoterol and prenalterol), beta(2)-(procaterol and salbutamol) and beta(3)-((+/-)-(R(*), R(*))-[4-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]amino]propyl]phenoxy]acetic acid, BRL37344) adrenoceptors inhibited the elevation of [Ca(2+)](i) elicited by phenylephrine (20 microM) with a rank order of BRL37344> or =xamoterol> or =isoprenaline>procaterol> or =prenalterol>salbutamol. The xamoterol effect was reversed by ICI 118,551 (100 nM), but not by 1-(2-ethylphenoxy)-3-[[(1S)-1,2,3,4-tetrahydro-1-naphthalenyl]amino]-(2S)-2-propanol (SR59230A, 100 nM) or atenolol (1 microM). The BRL37344 effect was reversed by SR59230A (100 nM), but not by atenolol (1 microM) or ICI 118,551 (100 nM). Both xamoterol and BRL37344 inhibited phenylephrine-induced tissue contractility. This study shows that both xamoterol and BRL37344 are effective inhibitors of phenylephrine-induced effects in human cultured prostatic stromal cells and in prostatic tissue.
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Affiliation(s)
- John M Haynes
- Prostate Research Cooperative, Victorian College of Pharmacy, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
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138
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Chang CZ, Dumont AS, Simsek S, Titus BJ, Kwan AL, Kassell NF, Solenski NJ. THE ADENOSINE 2A RECEPTOR AGONIST ATL-146E ATTENUATES EXPERIMENTAL POSTHEMORRHAGIC VASOSPASM. Neurosurgery 2007; 60:1110-7; discussion 1117-8. [PMID: 17538386 DOI: 10.1227/01.neu.0000255467.22387.5c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Selective adenosine 2A receptor agonists, such as ATL-146e, are known to be potent anti-inflammatory agents devoid of systemic side effects and have been used clinically in a number of disease states. However, adenosine 2A receptor agonists have not been studied in the treatment of cerebral vasospasm after subarachnoid hemorrhage. The present study investigated the efficacy of ATL-146e in the prevention of leukocyte infiltration and attenuation of posthemorrhagic vasospasm. METHODS The rodent femoral artery model of vasospasm was used. Forty male Sprague-Dawley rats were randomly assigned to four different groups (vehicle, 1 ng/kg/min, 10 ng/kg/min, or 100 ng/kg/min ATL-146e administered via subcutaneous osmotic minipump). Vasospasm was evaluated at posthemorrhage Day 8 (period of peak constriction) by calculating the lumen cross-sectional area (expressed as percent change in luminal area: ratio of blood-exposed vessel to normal saline-exposed vessel) and radial wall thickness. Immunostaining with anti-CD45 monoclonal antibody to detect leukocytes was used to evaluate localized inflammation. RESULTS Significant vasospasm was noted in the vehicle-treated (blood-exposed) control group (78.5%, P < 0.001; expressed as a ratio of luminal area of the saline [no blood] control), but not in the ATL-146e-treated groups (lumen ratio to control: 105.0, 83.4, and 91.3% for the 1, 10, and 100 ng/kg/min groups, respectively). Additionally, infiltration of inflammatory cells was reduced significantly and radial wall thickness was decreased in the ATL-146e-treated groups compared with the vehicle-treated control group. CONCLUSION Selective activation of the adenosine 2A receptor with ATL-146e prevented posthemorrhagic vasospasm and reduced leukocyte infiltration in this experimental model. This agent is worthy of further investigation and lends credence to the hypothesis supporting a role for inflammation in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage.
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Affiliation(s)
- Chih-Zen Chang
- Department of Neurological Surgery, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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139
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Akata T. Cellular and molecular mechanisms regulating vascular tone. Part 2: regulatory mechanisms modulating Ca2+ mobilization and/or myofilament Ca2+ sensitivity in vascular smooth muscle cells. J Anesth 2007; 21:232-42. [PMID: 17458653 DOI: 10.1007/s00540-006-0488-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 11/21/2006] [Indexed: 11/25/2022]
Abstract
Understanding the physiological mechanisms regulating vascular tone would lead to better circulatory management during general anesthesia. This two-part review provides an overview of current knowledge about the cellular and molecular mechanisms regulating the contractile state of vascular smooth muscle cells (i.e., vascular tone). The first part reviews basic mechanisms controlling the cytosolic Ca2+ concentration in vascular smooth muscle cells, and the Ca2+-dependent regulation of vascular tone. This second part reviews the regulatory mechanisms modulating Ca2+ mobilization and/or myofilament Ca2+ sensitivity in vascular smooth muscle cells-including Rho/Rho kinase, protein kinase C, arachidonic acid, Ca2+/calmodulin-dependent protein kinase II, caldesmon, calponin, mitogen-activated protein kinases, tyrosine kinases, cyclic nucleotides, Cl- channels, and K+ channels.
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Affiliation(s)
- Takashi Akata
- Department of Anesthesiology and Critical Care Medicine, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan
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140
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Han W, Tang X, Wu H, Liu Y, Zhu D. Role of ERK1/2 signaling pathways in 4-aminopyridine-induced rat pulmonary vasoconstriction. Eur J Pharmacol 2007; 569:138-44. [PMID: 17537430 DOI: 10.1016/j.ejphar.2007.04.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2007] [Revised: 04/05/2007] [Accepted: 04/19/2007] [Indexed: 10/23/2022]
Abstract
The aim of the present study was to investigate the contribution of extracellular signal regulated kinase-1/2 (ERK1/2) to pulmonary artery contraction in response to 4-aminopyridione (4-AP), an inhibitor of a voltage-gated K(+) channels that regulate pulmonary vascular tone. Pulmonary artery rings 1-1.5 mm in diameter from male adult Wistar rat were isolated and cut into 3-mm in length. ERK1/2 up-stream kinase (MEK) inhibitors 2'-amino-3'-methoxyflavone (PD98059) and 1,4-diamino-2,3-dicyano-1,4-bis (2-aminophenylthio)-butadiene (U0126), which block the activation of ERK1/2, were used to test the role of ERK1/2 in 4-AP induced pulmonary arterial vasoconstriction and the influences of 4-AP on expressions of phosphorylated ERK1/2 (p-ERK1/2) in cultured rat pulmonary arterial smooth muscle cells (PASMCs) and whole tissues. Our results show that 4-AP elicited concentration-dependent increases in tension of rat pulmonary artery rings, effects that were reduced by pretreatment of the rings with ERK inhibitors, PD98059 (20 microM) and U0126 (10 microM). Moreover, 4-AP increased the expressions of p-ERK1/2 in cultured PASMCs s and whole tissues, which were prevented by pretreatment of the cells or tissues with U0126. These results indicate that ERK1/2 signaling pathway contributes to pulmonary vasoconstriction induced by 4-AP.
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MESH Headings
- 4-Aminopyridine/pharmacology
- Animals
- Blotting, Western
- Butadienes/pharmacology
- Cells, Cultured
- Dose-Response Relationship, Drug
- Enzyme Inhibitors/pharmacology
- Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Flavonoids/pharmacology
- In Vitro Techniques
- Lung/blood supply
- Lung/drug effects
- Lung/physiology
- MAP Kinase Signaling System/drug effects
- Male
- Mitogen-Activated Protein Kinase 1/antagonists & inhibitors
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/antagonists & inhibitors
- Mitogen-Activated Protein Kinase 3/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitriles/pharmacology
- Phosphorylation/drug effects
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Voltage-Gated/antagonists & inhibitors
- Potassium Channels, Voltage-Gated/physiology
- Pulmonary Artery/cytology
- Pulmonary Artery/drug effects
- Pulmonary Artery/physiology
- Rats
- Rats, Wistar
- Time Factors
- Vasoconstriction/drug effects
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Affiliation(s)
- Weina Han
- College of Pharmacy, Harbin Medical University, 157 Baojian Road, Nangang District, Harbin, Heilongjiang 150081, P.R. of China
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141
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Abstract
The excitability of smooth muscle cells is regulated, in part, by stretch-activated ion channels in the plasma membrane. The response to stretch of a particular muscle or organ is tuned to specific functional needs by the types of ion channels expressed. Mechanosensitive ionic conductances that yield either inward or outward currents have been observed in and characterized in studies of smooth muscles. In vascular muscles, the dominant response to stretch is muscle contraction (the myogenic response). This chapter proposes several mechanisms for the myogenic response; one of these hypotheses involves stretch-dependent activation of nonselective cation channels. The inward current resulting from an activation of these channels causes plasma membrane depolarization, activation of voltage-gated Ca(2+) channels, Ca(2+) entry, and excitation-contraction coupling. Thus, increasing the vascular pressure and distension of blood vessels cause responsive vasoconstriction. Other conductances are also proposed as participants in the myogenic response, and progress characterizing the inward current channels responsive to stretch is summarized. Outward currents responding to muscle stretch are also present in smooth muscles. For example, expression of stretch-sensitive two-pore domain K(+) (K2P) channels has been reported in visceral smooth muscles. These organs resist contraction on filling and provide a reservoir function. Stretch-dependent outward current channels are hypothesized to help stabilize membrane potential until it becomes desirable to empty the stored contents. Mechanosensitive conductances participate in the integrated responses of smooth muscle tissues. The chapter summarizes the class of channels found in smooth muscles.
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142
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Wu C, Hayama E, Imamura SI, Matsuoka R, Nakanishi T. Developmental changes in the expression of voltage-gated potassium channels in the ductus arteriosus of the fetal rat. Heart Vessels 2007; 22:34-40. [PMID: 17285444 DOI: 10.1007/s00380-006-0926-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Accepted: 05/12/2006] [Indexed: 11/27/2022]
Abstract
Oxygen-sensitive, voltage-gated potassium channels (Kv) may contribute to the determination of the membrane potential in smooth muscle cells of the ductus arteriosus (DA), and thus to regulation of contractile tone in response to oxygen. Developmental changes in Kv during gestation may be related to closure of the DA after birth. This study investigated developmental changes in the expression of Kv in the DA and compared it with that of the pulmonary artery (PA) and the aorta (Ao). The DA, PA, and Ao were isolated from fetal rats at days 19 and 21 of gestation (term: 21.5 days). The expression of Kv1.2, Kv1.5, Kv2.1, and Kv3.1, putative oxygen-sensitive Kv channels that open in response to oxygen, was evaluated at both the mRNA and protein levels, using quantitative real-time polymerase chain reaction and immunohistochemistry. In the Kv family studied, Kv1.5 mRNA was expressed most abundantly in the DA, PA, and Ao in both day-19 and day-21 fetuses. Although the expression levels of Kv1.2, Kv1.5, Kv2.1, and Kv3.1 did not change much with development in the PA and Ao, in the DA they decreased with development. The decrease in the expression of Kv channels may enhance DA closure after birth by eliminating the opening of Kv channels when oxygen increases.
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Affiliation(s)
- Cuijiao Wu
- Department of Pediatric Cardiology, The Heart Institute of Japan, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan
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143
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Fike CD, Kaplowitz MR, Zhang Y, Madden JA. Voltage-gated K+ channels at an early stage of chronic hypoxia-induced pulmonary hypertension in newborn piglets. Am J Physiol Lung Cell Mol Physiol 2006; 291:L1169-76. [PMID: 16861383 DOI: 10.1152/ajplung.00117.2006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our purpose was to determine whether smooth muscle cell membrane properties are altered in small pulmonary arteries (SPA) of piglets at an early stage of pulmonary hypertension. Piglets were raised in either room air (control) or hypoxia for 3 days. A microelectrode technique was used to measure smooth muscle cell membrane potential ( Em) in cannulated, pressurized SPA (100- to 300-μm diameter). SPA responses to the voltage-gated K+ (KV) channel antagonist 4-aminopyridine (4-AP) and the KV1 family channel antagonist correolide were measured. Other SPA were used to assess amounts of KV1.2, KV1.5, and KV2.1 (immunoblot technique). Em was more positive in SPA of chronically hypoxic piglets than in SPA of comparable-age control piglets. The magnitude of constriction elicited by either 4-AP or correolide was diminished in SPA from hypoxic piglets. Abundances of KV1.2 were reduced, whereas abundances of both KV1.5 and KV2.1 were unaltered, in SPA from hypoxic piglets. At least partly because of reduced amounts of KV1.2, smooth muscle cell membrane properties are altered such that Em is depolarized and KV channel family function is impaired in SPA of piglets at an early stage of chronic hypoxia-induced pulmonary hypertension.
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Affiliation(s)
- Candice D Fike
- Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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144
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Lima R, Tardim JCBM, Barros ME, Boim MA. Role of ATP-sensitive potassium channels in normal and hypertension-associated pregnancy in rats. Clin Exp Pharmacol Physiol 2006; 33:780-6. [PMID: 16922806 DOI: 10.1111/j.1440-1681.2006.04438.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Activation of vascular ATP-sensitive K(+) (K(ATP)) channels has been implicated in vasodilator responses to pregnancy. 2. The effect of glibenclamide, a K(ATP) channel inhibitor, on systolic blood pressure (SBP) and renal function was evaluated in pregnant and non-pregnant spontaneously hypertensive rats, as well as in normotensive and hypertensive Wistar rats that had been made hypertensive by simultaneous treatment with N(G)-nitro-l-arginine methyl ester (0.4 mg/mL) and indomethacin (2 mg/kg, i.p.) from Day 1 of gestation. Pregnant animals received 10 mg/kg glibenclamide for 12 days starting at Day 7. In addition, the mRNA levels of the vascular K(ATP) channel (Kir6.2) were estimated in aorta and kidney using real-time reverse transcription-polymerase chain reaction on Day 19 of pregnancy. 3. The decreased SBP observed in pregnant Wistar rats was paralleled by an increase in Kir6.2 mRNA levels. Glibenclamide blunted systemic vasodilation and reduced the mRNA expression of Kir6.2. There was no pregnancy induced vasodilation and no change in Kir6.2 mRNA expression in SHR. Glibenclamide had no effect on pregnant SHR. Hypertensive Wistar rats exhibited high SBP, followed by increased Kir6.2 mRNA levels. The effects of glibenclamide were not evaluated in this group because glibenclamide induced intense vaginal bleeding. 4. The results of the present study suggest that K(ATP) channels may be involved in pregnancy induced vasodilation during normotensive pregnancy, but not in pregnant SHR. Glibenclamide may have an abortive effect if administered during the early phases of gestation or in association with nitric oxide and prostaglandin inhibitors.
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Affiliation(s)
- R Lima
- Universidade Federal de São Paulo, Renal Division, São Paulo, Brazil
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145
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Schach C, Xu M, Platoshyn O, Keller SH, Yuan JXJ. Thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels. Am J Physiol Lung Cell Mol Physiol 2006; 292:L685-98. [PMID: 17098807 DOI: 10.1152/ajplung.00276.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cellular redox change regulates pulmonary vascular tone by affecting function of membrane and cytoplasmic proteins, enzymes, and second messengers. This study was designed to test the hypothesis that functional modulation of ion channels by thiol oxidation contributes to regulation of excitation-contraction coupling in isolated pulmonary artery (PA) rings. Acute treatment with the thiol oxidant diamide produced a dose-dependent relaxation in PA rings; the IC50 was 335 and 58 microM for 40 mM K+ - and 2 microM phenylephrine-induced PA contraction, respectively. The diamide-mediated pulmonary vasodilation was affected by neither functional removal of endothelium nor 8-bromoguanosine-3'-5'-cyclic monophosphate (50 microM) and HA-1004 (30 microM). A rise in extracellular K+ concentration (from 20 to 80 mM) attenuated the thiol oxidant-induced PA relaxation. Passive store depletion by cyclopiazonic acid (50 microM) and active store depletion by phenylephrine (in the absence of external Ca2+ both induced PA contraction due to capacitative Ca2+ entry. Thiol oxidation by diamide significantly attenuated capacitative Ca2+ entry-induced PA contraction due to active and passive store depletion. The PA rings isolated from left and right PA branches appeared to respond differently to store depletion. Although the active tension induced by passive store depletion was comparable, the active tension induced by active store depletion was 3.5-fold greater in right branches than in left branches. These data indicate that thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels, which subsequently attenuate Ca2+ influx and decrease cytosolic free Ca2+ concentration in pulmonary artery smooth muscle cells. The mechanisms involved in thiol oxidation-mediated pulmonary vasodilation or activation of K+ channels and inhibition of store-operated Ca2+ channels appear to be independent of functional endothelium and of the cGMP-dependent protein kinase pathway.
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Affiliation(s)
- Christian Schach
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0725, La Jolla, CA 92093-0725, USA
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146
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Wu BN, Luykenaar KD, Brayden JE, Giles WR, Corteling RL, Wiehler WB, Welsh DG. Hyposmotic challenge inhibits inward rectifying K+ channels in cerebral arterial smooth muscle cells. Am J Physiol Heart Circ Physiol 2006; 292:H1085-94. [PMID: 17056667 DOI: 10.1152/ajpheart.00926.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study sought to define whether inward rectifying K(+) (K(IR)) channels were modulated by vasoactive stimuli known to depolarize and constrict intact cerebral arteries. Using pressure myography and patch-clamp electrophysiology, initial experiments revealed a Ba(2+)-sensitive K(IR) current in cerebral arterial smooth muscle cells that was active over a physiological range of membrane potentials and whose inhibition led to arterial depolarization and constriction. Real-time PCR, Western blot, and immunohistochemical analyses established the expression of both K(IR)2.1 and K(IR)2.2 in cerebral arterial smooth muscle cells. Vasoconstrictor agonists known to depolarize and constrict rat cerebral arteries, including uridine triphosphate, U46619, and 5-HT, had no discernable effect on whole cell K(IR) activity. Control experiments confirmed that vasoconstrictor agonists could inhibit the voltage-dependent delayed rectifier K(+) (K(DR)) current. In contrast to these observations, a hyposmotic challenge that activates mechanosensitive ion channels elicited a rapid and sustained inhibition of the K(IR) but not the K(DR) current. The hyposmotic-induced inhibition of K(IR) was 1) mimicked by phorbol-12-myristate-13-acetate, a PKC agonist; and 2) inhibited by calphostin C, a PKC inhibitor. These findings suggest that, by modulating PKC, mechanical stimuli can regulate K(IR) activity and consequently the electrical and mechanical state of intact cerebral arteries. We propose that the mechanoregulation of K(IR) channels plays a role in the development of myogenic tone.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Animals
- Cerebral Arteries/drug effects
- Cerebral Arteries/metabolism
- Female
- Hypotonic Solutions
- In Vitro Techniques
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Naphthalenes/pharmacology
- Patch-Clamp Techniques
- Potassium Channels, Inwardly Rectifying/drug effects
- Potassium Channels, Inwardly Rectifying/metabolism
- Protein Kinase C/metabolism
- Protein Kinase Inhibitors/pharmacology
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Serotonin/pharmacology
- Tetradecanoylphorbol Acetate/analogs & derivatives
- Tetradecanoylphorbol Acetate/pharmacology
- Uridine Triphosphate/pharmacology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Bin-Nan Wu
- Department and Graduate Institute of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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147
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McGahon MK, Dawicki JM, Arora A, Simpson DA, Gardiner TA, Stitt AW, Scholfield CN, McGeown JG, Curtis TM. Kv1.5 is a major component underlying the A-type potassium current in retinal arteriolar smooth muscle. Am J Physiol Heart Circ Physiol 2006; 292:H1001-8. [PMID: 17040965 PMCID: PMC2593469 DOI: 10.1152/ajpheart.01003.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Little is known about the molecular characteristics of the voltage-activated K+ (Kv) channels that underlie the A-type K+ current in vascular smooth muscle cells of the systemic circulation. We investigated the molecular identity of the A-type K+ current in retinal arteriolar myocytes using patch-clamp techniques, RT-PCR, immunohistochemistry, and neutralizing antibody studies. The A-type K+ current was resistant to the actions of specific inhibitors for Kv3 and Kv4 channels but was blocked by the Kv1 antagonist correolide. No effects were observed with pharmacological agents against Kv1.1/2/3/6 and 7 channels, but the current was partially blocked by riluzole, a Kv1.4 and Kv1.5 inhibitor. The current was not altered by the removal of extracellular K+ but was abolished by flecainide, indicative of Kv1.5 rather than Kv1.4 channels. Transcripts encoding Kv1.5 and not Kv1.4 were identified in freshly isolated retinal arterioles. Immunofluorescence labeling confirmed a lack of Kv1.4 expression and revealed Kv1.5 to be localized to the plasma membrane of the arteriolar smooth muscle cells. Anti-Kv1.5 antibody applied intracellularly inhibited the A-type K+ current, whereas anti-Kv1.4 antibody had no effect. Co-expression of Kv1.5 with Kvβ1 or Kvβ3 accessory subunits is known to transform Kv1.5 currents from delayed rectifers into A-type currents. Kvβ1 mRNA expression was detected in retinal arterioles, but Kvβ3 was not observed. Kvβ1 immunofluorescence was detected on the plasma membrane of retinal arteriolar myocytes. The findings of this study suggest that Kv1.5, most likely co-assembled with Kvβ1 subunits, comprises a major component underlying the A-type K+ current in retinal arteriolar smooth muscle cells.
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Affiliation(s)
- Mary K McGahon
- Centre of Vision Sciences, The Queen's University of Belfast, Institute of Clinical Sciences, The Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA. UK
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148
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Park WS, Son YK, Kim N, Youm JB, Warda M, Ko JH, Ko EA, Kang SH, Kim E, Earm YE, Han J. Direct modulation of Ca(2+)-activated K(+) current by H-89 in rabbit coronary arterial smooth muscle cells. Vascul Pharmacol 2006; 46:105-13. [PMID: 17052962 DOI: 10.1016/j.vph.2006.08.413] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 05/18/2006] [Accepted: 08/28/2006] [Indexed: 10/24/2022]
Abstract
The effects of H-89, a potent and selective inhibitor of protein kinase A (PKA) on Ca(2+)-activated K(+) (BK(Ca)) channels in coronary arterial smooth muscle cells were examined using a patch-clamp technique. In inside-out configuration, H-89 increased the NP(o) of the BK(Ca) channel, but it reduced the dwell time of BK(Ca) currents. In whole-cell configuration, H-89 markedly increased BK(Ca) currents in a concentration-dependent manner. The EC(50) was 0.470+/-0.0741 microM based on dwell time, 0.582+/-0.0691 microM based on the NP(o), and 0.519+/-0.0295 microM based on the whole-cell current, respectively. H-85, which is an inactive form of H-89, increased BK(Ca) currents, similar to the result of H-89. The other PKA inhibitors (Rp-8-CPT-cAMPs and KT 5720) and protein phosphatase inhibitor (okadaic acid, 1 microM) had little effect on BK(Ca) currents and did not significantly alter the stimulatory effects of 1 microM H-89. These findings suggest that H-89 increases the BK(Ca) current independently of PKA.
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Affiliation(s)
- Won Sun Park
- Department of Physiology and Biophysics, College of Medicine, Cardiovascular and Metabolic Disease Research Center, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
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149
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Rainbow RD, Hardy MEL, Standen NB, Davies NW. Glucose reduces endothelin inhibition of voltage-gated potassium channels in rat arterial smooth muscle cells. J Physiol 2006; 575:833-44. [PMID: 16825302 PMCID: PMC1995678 DOI: 10.1113/jphysiol.2006.114009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Prolonged hyperglycaemia impairs vascular reactivity and inhibits voltage-activated K(+) (Kv) channels. We examined acute effects of altering glucose concentration on the activity and inhibition by endothelin-1 (ET-1) of Kv currents of freshly isolated rat arterial myocytes. Peak Kv currents recorded in glucose-free solution were reversibly reduced within 200 s by increasing extracellular glucose to 4 mm. This inhibitory effect of glucose was abolished by protein kinase C inhibitor peptide (PKC-IP), and Kv currents were further reduced in 10 mm glucose. In current-clamped cells, membrane potentials were more negative in 4 than in 10 mm glucose. In 4 mm d-glucose, 10 nm ET-1 decreased peak Kv current amplitude at +60 mV from 23.5 +/- 3.3 to 12.1 +/- 3.1 pA pF(-1) (n = 6, P < 0.001) and increased the rate of inactivation, decreasing the time constant around fourfold. Inhibition by ET-1 was prevented by PKC-IP. When d-glucose was increased to 10 mm, ET-1 no longer inhibited Kv current (n = 6). Glucose metabolism was required for prevention of ET-1 inhibition of Kv currents, since fructose mimicked the effects of d-glucose, while l-glucose, sucrose or mannitol were without effect. Endothelin receptors were still functional in 10 mm d-glucose, since pinacidil-activated ATP-dependent K(+) (K(ATP)) currents were reduced by 10 nm ET-1. This inhibition was nearly abolished by PKC-IP, indicating that endothelin receptors could still activate PKC in 10 mm d-glucose. These results indicate that changes in extracellular glucose concentration within the physiological range can reduce Kv current amplitude and can have major effects on Kv channel modulation by vasoconstrictors.
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Affiliation(s)
- R D Rainbow
- Department of Cell Physiology and Pharmacology, University of Leicester, PO Box 138, Leicester LE1 9HN, UK
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150
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Rhyu MR, Kim JH, Kim EY. Radix angelica elicits both nitric oxide-dependent and calcium influx-mediated relaxation in rat aorta. J Cardiovasc Pharmacol 2006; 46:99-104. [PMID: 15965361 DOI: 10.1097/01.fjc.0000164092.88821.49] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study examined the vascular relaxation produced by Radix Angelica (AG; Dong Quai) and its possible mechanisms in isolated rat aortic rings precontracted with norepinephrine. The butanolic fraction (AgBt) of the crude extract of AG causes gradual endothelium-independent relaxation, which was unaffected by five different potassium channel inhibitors. AgBt attenuated the CaCl2-induced vasoconstriction in high-potassium depolarized medium; this required less than one-tenth the concentration needed to elicit vascular relaxation. An aqueous fraction (AgDw) of the crude extract induced transient acute relaxation, which was virtually abolished by endothelial ablation and pretreatment with L-NNA. L-Arginine fully reversed the action of L-NNA. Methylene blue and atropine significantly attenuated the relaxation, but indomethacin did not. Ferulic acid, the main active component in AG, relaxed both endothelium-intact and -denuded rings, while L-NNA, methylene blue, or atropine did not modify the relaxation. Ferulic acid also did not attenuate the CaCl2-induced contraction in high-potassium depolarized medium. In conclusion, Radix Angelica leads to both endothelium-dependent and -independent relaxation of isolated rat aorta. Increased formation of NO might contribute to the endothelium-mediated relaxation, while inhibition of the calcium influx might be an important mechanism in direct smooth muscle relaxation. A substance other than ferulic acid might create these effects.
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Affiliation(s)
- Mee-Ra Rhyu
- Function Research Division, Korea Food Research Institute, Gyeonggi-Do, Korea.
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