Effect of hypoxia on contraction and 45Ca2+ uptake induced by the thromboxane mimetic U46619 in sheep coronary artery.
The thromboxane mimetic U46619 (11 alpha,9 alpha-epoxymethano PGH2) increased 45Ca2+ uptake in sheep coronary artery rings. A larger increase occurred in endothelium-denuded than in endothelium-inact rings (increase in 45Ca2+ uptake: endothelium intact = 9.6 +/- 3.8, endothelium-denuded = 33.2 +/- 8.1 nmol g-1), in agreement with the increase in U46619 contraction produced by endothelium denudation. Hypoxia (PO2 = 4 mm Hg) inhibited both the U46619 contraction (at the U46619 EC50, contraction under oxygenated conditions = 158 +/- 35, under hypoxic conditions = 105 +/- 40 g cm-2) and the U46619-stimulated 45Ca2+ uptake. It is concluded that inhibition, by hypoxia, of the U46619 contractile effect on sheep coronary artery rings may be in part due to inhibition of U46619-stimulated 45Ca2+ uptake.
Dalen
T
T
Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, Scotland, UK.
Vestereng
M
M
Wadsworth
R
R
Kane
K
K
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes / Q000378:metabolism; D003331:Coronary Vessels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology*; D012756:Sheep; D013928:Thromboxane A2 / Q000031:analogs & derivatives* / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D002132:Calcium Radioisotopes; D011450:Prostaglandin Endoperoxides, Synthetic; D014665:Vasodilator Agents; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D002118:Calcium