Involvement of Gi/o in the PAR-4-induced NO production in endothelial cells.
We investigated the involvement of G(i/o) protein in NO production following the activation of proteinase-activated receptor-4 (PAR-4) in cultured bovine aortic endothelial cells. AYPGKF-NH(2) (PAR-4 activating peptide), thrombin, and ionomycin induced a concentration-dependent NO production, with the maximal production seen at 30 microM, 0.1U/ml, and 1 microM, respectively. Ionomycin elevated [Ca(2+)](i) in a concentration-dependent manner. However, AYPGKF-NH(2) and thrombin induced no [Ca(2+)](i) elevation. The loading of cells with BAPTA almost completely inhibited both the NO production and [Ca(2+)](i) elevation induced by 1 microM ionomycin, while it had no significant effect on the AYPGKF-NH(2)-induced NO production. Treatment with pertussis toxin inhibited the AYPGKF-NH(2)-induced NO production, while it had no effect on the ionomycin-induced NO production. Our findings thus demonstrate, for the first time, that PAR-4 activation induced NO production in a manner mostly independent of the Ca(2+) signal and also that G(i/o) is involved in such NO production in vascular endothelial cells.
Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Fumi
F
Momota
Katsuya
K
Hirano
Mayumi
M
Hirano
Junji
J
Nishimura
Hideo
H
Kanaide
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002417:Cattle; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000502:physiology*; D007202:Indicators and Reagents / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D009842:Oligopeptides / Q000502:physiology; D037342:Pertussis Toxin / Q000494:pharmacology; D018179:Receptors, Thrombin / Q000502:physiology*; D013917:Thrombin / Q000502:physiology
C482003:AYPGKG-NH(2); D007202:Indicators and Reagents; D007476:Ionophores; D009842:Oligopeptides; D018179:Receptors, Thrombin; D009569:Nitric Oxide; D004533:Egtazic Acid; D015759:Ionomycin; D037342:Pertussis Toxin; D013917:Thrombin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C112908:protease-activated receptor 4; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid