Momota Fumi, Hirano Katsuya, Hirano Mayumi, Nishimura Junji, Kanaide Hideo
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.
Biochem Biophys Res Commun. 2006 Apr 7;342(2):365-71. doi: 10.1016/j.bbrc.2006.01.165. Epub 2006 Feb 8.
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+) in a concentration-dependent manner. However, AYPGKF-NH(2) and thrombin induced no Ca(2+) elevation. The loading of cells with BAPTA almost completely inhibited both the NO production and Ca(2+) 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.
我们研究了在培养的牛主动脉内皮细胞中，蛋白酶激活受体-4（PAR-4）激活后G(i/o)蛋白在一氧化氮（NO）生成中的作用。AYPGKF-NH₂（PAR-4激活肽）、凝血酶和离子霉素均可诱导浓度依赖性的NO生成，最大生成量分别在30微摩尔、0.1单位/毫升和1微摩尔时出现。离子霉素以浓度依赖性方式升高细胞内钙离子浓度（[Ca²⁺]i）。然而，AYPGKF-NH₂和凝血酶并未诱导[Ca²⁺]i升高。用BAPTA处理细胞几乎完全抑制了1微摩尔离子霉素诱导的NO生成和[Ca²⁺]i升高，而对AYPGKF-NH₂诱导的NO生成无显著影响。百日咳毒素处理抑制了AYPGKF-NH₂诱导的NO生成，而对离子霉素诱导的NO生成无影响。因此，我们的研究结果首次证明，PAR-4激活以大多独立于Ca²⁺信号的方式诱导NO生成，并且G(i/o)参与血管内皮细胞中的这种NO生成。
