AJP - Heart and Circulatory Physiology, Vol 271, Issue 6 2290-H2299, Copyright © 1996 by American Physiological Society

ARTICLES

Low PO2 inhibits calcium channel activity in arterial smooth muscle cells

A. Franco-Obregon and J. Lopez-Barneo
Departamento de Fisiologia Medica y Biofisica, Facultad de Medicina, Seville, Spain.

We studied the effect of O2 tension (PO2) on the activity of voltage-gated Ca2+ channels recorded in whole cell patch-clamped smooth muscle cells enzymatically dispersed from rabbit cerebral, celiac, femoral, and main pulmonary arteries, as well as from the porcine coronary artery. In all myocyte classes examined, a reduction of PO2 (hypoxia) produced a rapid and reversible inhibition of the macroscopic L-type Ca2+ current of similar general characteristics. The hypoxic inhibition of Ca2+ channel activity closely followed the time course of bath exchange, first becoming apparent at below approximately 80 mmHg PO2. The interaction of O2 with the Ca2+ channels was strongly voltage dependent. At -30 mV the average extent of current inhibition was approximately 80%; however, no effect or even potentiation of current amplitude was observed at potentials more positive than +30 mV. Hypoxia selectively slowed activation kinetics (approximately 1.5 times at -20 mV); however, channel deactivation and inactivation were unaltered by low PO2. In addition, hypoxia produced a reversible shift (8.1 +/- 1.0 mV, n = 12) of the Ca2+ conductance-voltage curve toward positive membrane potentials. We propose that the O2 sensitivity of Ca2+ channels may contribute to the well-known hypoxic dilatation of systemic and the main pulmonary arteries.

This article has been cited by other articles:

				D. Gebremedhin, K. Yamaura, and D. R. Harder Role of 20-HETE in the hypoxia-induced activation of Ca2+-activated K+ channel currents in rat cerebral arterial muscle cells Am J Physiol Heart Circ Physiol, January 1, 2008; 294(1): H107 - H120. [Abstract] [Full Text] [PDF]

				A. M. Coney and J. M. Marshall Contribution of {alpha}2-adrenoceptors and Y1 neuropeptide Y receptors to the blunting of sympathetic vasoconstriction induced by systemic hypoxia in the rat J. Physiol., August 1, 2007; 582(3): 1349 - 1359. [Abstract] [Full Text] [PDF]

				J. M. Quayle, M. R. Turner, H. E. Burrell, and T. Kamishima Effects of hypoxia, anoxia, and metabolic inhibitors on KATP channels in rat femoral artery myocytes Am J Physiol Heart Circ Physiol, July 1, 2006; 291(1): H71 - H80. [Abstract] [Full Text] [PDF]

				K. M. Gauthier Hypoxia-induced vascular smooth muscle relaxation: increased ATP-sensitive K+ efflux or decreased voltage-sensitive Ca2+ influx? Am J Physiol Heart Circ Physiol, July 1, 2006; 291(1): H24 - H25. [Full Text] [PDF]

				M. S. Wolin, M. Ahmad, and S. A. Gupte Oxidant and redox signaling in vascular oxygen sensing mechanisms: basic concepts, current controversies, and potential importance of cytosolic NADPH Am J Physiol Lung Cell Mol Physiol, August 1, 2005; 289(2): L159 - L173. [Abstract] [Full Text] [PDF]

				J. Lopez-Barneo, R. del Toro, K. L. Levitsky, M. D. Chiara, and P. Ortega-Saenz Regulation of oxygen sensing by ion channels J Appl Physiol, March 1, 2004; 96(3): 1187 - 1195. [Abstract] [Full Text] [PDF]

				Y.-X. Wang, Y.-M. Zheng, I. Abdullaev, and M. I. Kotlikoff Metabolic inhibition with cyanide induces calcium release in pulmonary artery myocytes and Xenopus oocytes Am J Physiol Cell Physiol, February 1, 2003; 284(2): C378 - C388. [Abstract] [Full Text] [PDF]

				W. Pajk, B. Schwarz, H. Knotzer, B. Friesenecker, A. Mayr, M. Dunser, and W. Hasibeder Jejunal tissue oxygenation and microvascular flow motion during hemorrhage and resuscitation Am J Physiol Heart Circ Physiol, December 1, 2002; 283(6): H2511 - H2517. [Abstract] [Full Text] [PDF]

				G. D. Thorne, S. Shimizu, and R. J. Paul Hypoxic vasodilation in porcine coronary artery is preferentially inhibited by organ culture Am J Physiol Cell Physiol, July 1, 2001; 281(1): C24 - C32. [Abstract] [Full Text] [PDF]

				Z. Ren, Q. Yang, H. S. Floten, A. P. Furnary, A. P.C. Yim, and G.-W. He ATP-sensitive potassium channel openers may mimic the effects of hypoxic preconditioning on the coronary artery Ann. Thorac. Surg., February 1, 2001; 71(2): 642 - 647. [Abstract] [Full Text] [PDF]

				L. C. Hool Hypoxia Increases the Sensitivity of the L-Type Ca2+ Current to {beta}-Adrenergic Receptor Stimulation via a C2 Region-Containing Protein Kinase C Isoform Circ. Res., December 8, 2000; 87(12): 1164 - 1171. [Abstract] [Full Text] [PDF]

				W. Long, Y. Zhao, L. Zhang, and L. D. Longo Role of Ca2+ channels in NE-induced increase in [Ca2+]i and tension in fetal and adult cerebral arteries Am J Physiol Regulatory Integrative Comp Physiol, July 1, 1999; 277(1): R286 - R294. [Abstract] [Full Text] [PDF]

				J. H. Lombard, Y. Liu, K. T. Fredricks, D. M. Bizub, R. J. Roman, and N. J. Rusch Electrical and mechanical responses of rat middle cerebral arteries to reduced PO2 and prostacyclin Am J Physiol Heart Circ Physiol, February 1, 1999; 276(2): H509 - H516. [Abstract] [Full Text] [PDF]

				K. Sward, K. Dreja, A. Lindqvist, E. Persson, and P. Hellstrand Influence of Mitochondrial Inhibition on Global and Local [Ca2+]i in Rat Tail Artery Circ. Res., April 19, 2002; 90(7): 792 - 799. [Abstract] [Full Text] [PDF]