Role of Gi/o-Src kinase-PI3K/Akt pathway and caveolin-1 in β2-adrenoceptor coupling to endothelial NO synthase in mouse pulmonary artery

摘要: Activation of the β₂-adrenoceptor (β₂-AR) elicits an endothelial nitric oxide synthase (eNOS)-dependent relaxation in mouse pulmonary artery, which, contrary to muscarinic receptor-dependent relaxation, is preserved hypoxic arterial hypertension. We therefore characterized signaling pathways underlying β₂-AR-mediated eNOS activation, with special focus on G(i/o) proteins, protein kinases and caveolae. Functional studies (for evaluation vasorelaxant response), Western blotting assessment caveolin-1 phosphorylation) transmission electron microscopy visualization caveolae) were conducted arteries from wild-type or knockout mice. In isolated arteries, selective β₂-AR agonist procaterol was reduced by inhibitors proteins (pertussis toxin, PTX), phosphatidylinositol 3-kinase (PI3K; wortmannin LY 294002), Akt (Akt inhibitor X) Src-kinase (PP2) cholesterol depletion (using methyl-β-cyclodextrin). Procaterol induced phosphorylation at Ser(1177), which prevented PTX, PP2 inhibitor. also promoted Tyr(14), decreased PTX PP2. Caveolin-1 gene deletion resulted caveolae disruption artery potentiation procaterol-induced relaxation. Unlike procaterol, acetylcholine-induced unaffected methyl-β-cyclodextrin deletion. To conclude, coupled a G(i/o)-Src kinase-PI3K/Akt pathway promote Ser(1177) leading NO-dependent vasorelaxation. exerts negative control this response that abrogated its through kinase pathway. Since β₂-AR- receptor-mediated relaxations differentiate their respective activation sensitivities during hypoxia-induced hypertension, mechanisms might be key determinants dysfunction.