| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
To investigate the signal transduction mechanisms by which agonists activate NO, we examined, using a cranial window, dilator responses of the basilar artery to acetylcholine (ACh) in vivo. We focasued on tyrosine kinase and phosphatidylinositol 3 (Pl3)-kinase. Topical application of ACh increased diameter of the basilar artery in a concentration-related manner. Inhibitors of tyrosine kinase and Pl3-kinase attenuated ACh-induced vasodilatation without affecting vasodilatation produced by sodium nitroprusside, an NO donor. To examine the role of both kinases in ACh-induced calcium signaling, we measured intracellular free calcium concentration ([Ca^<2+>]i) of cultured rat basilar arterial endothelial cells (EC) using a fluorescent calcium indicator, indo 1. Genistein, an inhibitor of tyrosine kinase, markedly attenuated ACh-induced calcium influx to the cells, however, wortmannin had no effects on ACh-induced calcium changes. These results suggest that ACh-induced dilatation of the basilar artery is mediated, at least in part, by activation of tyrosine kinase and Pl 3-kinase in vivo. ACh-induced calcium influx to the EC may be mediated by activation of tyrosine kinase. Pl 3-kinase may play an important role in the ACh-induced NOproduction in a calcium-independent manner.
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