Mechanism of endothelin-1-induced contraction in rabbit basilar artery

Background and Purpose-Endothelin-1 (ET-1) is suggested to be a major cause of cerebral vasospasm after subarachnoid hemorrhage. However, the mechanis m of ET-1-induced contraction in cerebral arteries remains unclear. This st udy was undertaken to demonstrate the possible role of protein tyrosine kin ase (PTK), mitogen-activated protein kinase (MAPK), and protein kinase C (P KC) in ET-l-induced contraction. Methods-PD-98059, damnacanthal, wortmannin, AG-490, genistein, calphostin C , and staurosporine were used to inhibit, or relax, the ET-1-induced contra ction of basilar artery, studied with an isometric tension system. Immunopr ecipitation of MAPK in ET-1-stimultated rings of basilar artery without or with the above inhibitors was studied with Western blot. Results-(1) ET-1 produced concentration-dependent contraction and MAPK immu noprecipitation in rabbit basilar artery by activation of ETA but not ETB r eceptors. (2) MAPK inhibitors PD-98059 and U-0126 produced dose-dependent i nhibition of ET-1-induced contraction. (3) The Src tyrosine kinase inhibito r damnacanthal. the phosphatidylinositol-3 kinase inhibitor wortmannin, and the Janus tyrosine kinase, inhibitor AG-490 abolished ET-l-induced contrac tion. (4) The PKC inhibitor staurosporine but not calphostin C abolished ET -l-induced contraction, and the PTK inhibitor genistein partially reduced E T-l-induced contraction. (5) In arteries precontracted by ET-I, PD-980591 U -0126, wortmannin, AG-490, genistein, and staurosporine produced concentrat ion-dependent relaxation. (6) ET-I induced a biphasic and time-dependent MA PK immunoprecipitation. (7) PD-98059, U-0126, genistein, AG-490, and damnac anthal, but not staurosporine or wortmannin, abolished the effect of ET-I o n MAPK immunoreactivity. Conclusions-This study demonstrated that MAPK may be involved in ET-l-induc ed contraction in rabbit basilar artery. MAPK is downstream of PTK, Src, an d Janus tyrosine kinase pathways but may not be downstream of phosphatidyli nositol-3 kinase pathways. The possible involvement of PKC in ET-1-induced contraction requires further investigation. Inhibition of these pathways ma y offer alternative treatment for ET-1-induced contraction and cerebral vas ospasm.