Role of PI3-kinase in isoproterenol and IGF-1 induced ecNOS activity.
Phosphatidylinositol 3-kinase (PI3-K) has been shown to mediate insulin and insulin-like growth factor-1 (IGF-1)-induced nitric oxide (NO) generation and, thus, vascular tone. A role for PI3-K in G-protein-coupled receptor signal transduction has been reported. As beta (beta2)-adrenergic vascular actions are partly dependent on NO, we have investigated the role of PI3-K in isoproterenol (Iso) and IGF-1 induced endothelial NO synthase (ecNOS) activity in rat aortic endothelial cells (RAEC). Cell lysates of RAEC, exposed to Iso (10 micromol/L) for 5 min and 6 h, and to IGF-1 (100 nM) for 10 min and 6 h, or pretreated with PI3-K inhibitor Wortmannin (WT), were used for measuring PI3-K activity, p85kDa regulatory protein, and citrulline production. Results show that Iso and IGF-1 increased a p85 subunit and citrulline production, and also enhanced 32P incorporation into PIP3. Pretreatment with WT inhibited Iso-stimulated ecNOS, as well as, PI3-K activity. Iso enhanced association of ecNOS with the triton X-100-insoluble fraction of RAEC. These data indicate that the endothelial cell PI3-K pathway mediates, in part, the release of NO and subsequent vasorelaxation in response to this beta-agonist, as well as, IGF-1.
Isenović
E
E
Department of Medicine, State University New York-Health Science Center, Brooklyn, New York, USA.
Muniyappa
R
R
Milivojević
N
N
Rao
Y
Y
Sowers
J R
JR
D000818:Animals; D001011:Aorta / Q000166:cytology; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D004790:Enzyme Induction; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000502:physiology
D002316:Cardiotonic Agents; D007334:Insulin-Like Growth Factor I; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D019869:Phosphatidylinositol 3-Kinases; D007545:Isoproterenol