Modification by decreased temperature and hypoxia of 45Ca movements in stimulated smooth muscle of rabbit aorta.
In rabbit aortic smooth muscle, contractile responsiveness to 10(-6) M norepinephrine or 60 mM added K+ was inhibited by hypoxia (induced by 100% N2) or decreased bath temperature. Hypoxia increased K+-induced 45Ca efflux, inhibited K+-induced 45Ca uptake, and inhibited norepinephrine-induced 45Ca release; lowering bath temperature by 10 degrees C decreased resting 45Ca uptake and norepinephrine-induced 45Ca release by 30-40% and decreased the 45Ca uptake elicited with norepinephrine or K+ by more than two-thirds. Thus, hypoxia and temperature variations affect different Ca2+ components. Hypoxia decreases the norepinephrine-sensitive membrane Ca2+ fraction and the K+-stimulated mitochondrial Ca2+ fraction whereas decreased temperature most strongly inhibits membrane-associated Ca2+ uptake increases elicited with either norepinephrine or high K+.
D000818:Animals; D001011:Aorta / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D003080:Cold Temperature; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D010100:Oxygen; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects
D011188:Potassium; D010100:Oxygen; D002118:Calcium; D009638:Norepinephrine