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Role of different subtypes of P2 purinoceptor on cytosolic Ca2+ levels in rat aortic smooth muscle

1994; Elsevier BV; Volume: 266; Issue: 3 Linguagem: Inglês

10.1016/0922-4106(94)90135-x

1872-8251

Satoshi Kitajima, Hiroshi Ozaki, Hideaki Karaki,

Receptor Mechanisms and Signaling

The role of different subtypes of P2 purinoceptors on cytosolic Ca2+ level ([Ca2+]i) was examined in vascular smooth muscle of rat aorta. αβ-Methylene-ATP (P2x agonist), 2-methylthio-ATP (P2Y agonist), UTP and ATPγS (P2U agonists), and ATP (nonselective P2 agonist) induced a transient increase followed by a small sustained increase in [Ca2+]i in a concentration dependent manner. Among these agonists, αβ-methylene-ATP was the most potent. In the absence of extracellular Ca2+ (with 0.5 mM EGTA), ATP, UTP and ATPγS induced a transient increase in [Ca2+]i whereas αβ-methylene-ATP and 2-methylthio-ATP and ATPγS induced a rapid increase in [Ca2+]i followed by a sustained increase while αβ-methylene-ATP and 2-methylthio-ATP were ineffective. These results suggest that Ca2+ release from the intracellular Ca2+ store is mediated by P2U purinoceptor whereas Ca2+ influx is mediated by both P2X and P2U purinoceptors in the rat aortic smooth muscle.