title: Effect of pentobarbital on the contraction and calcium movements in cat cerebral and peripheral arteries.
abstract: Pentobarbital (PB) induced concentration-dependent vasodilation in cylindrical segments of cat cerebral and femoral arteries precontracted with 75 mM K+ or 10(-5) M serotonin (5-HT). PB (10(-4) or 10(-3) M, 10 min preincubations) caused concentration-dependent inhibition of the contraction produced by both agents. The exposure of the vessels to a Ca2+-free medium annulled the response elicited by K+ in both kinds of arteries. In this medium, the contraction induced by 5-HT in cerebral arteries was abolished, whereas in femoral ones it was significantly reduced. This residual response was abolished by PB. The intracellular 45Ca2+ uptake (La3+ method) elicited by K+ in both kinds of arteries and by 5-HT in cerebral ones was reduced in a concentration-dependent manner by PB (10(-4)-10(-3) M). The spontaneous 45Ca2+ efflux from these arteries and that induced by La3+ (10 mM) were unaffected by PB (10(-3) M). These results indicate that the vasodepressor effects induced by PB are essentially due to an interference of the barbiturate with the Ca2+ entry into the vascular smooth muscle cell in both kinds of arteries and with the intracellular Ca2+ movements in femoral ones. It does not seem to exist a clear selectivity of PB for brain or peripheral arteries for antagonizing the responses caused by K+ or 5-HT.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002415:Cats; D002536:Cerebral Arteries / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D005260:Female; D005263:Femoral Artery / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D010424:Pentobarbital / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D012701:Serotonin; D010424:Pentobarbital; D011188:Potassium; D002118:Calcium