Higaki T, Sawada S, Kono Y, Imamura H, Tada Y, Yamasaki S, Toratani A, Sato T, Komatsu S, Akamatsu N, Tamagaki T, Tsuda Y, Tsuji H, Nakagawa M
Second Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Microvasc Res. 1999 Sep;58(2):144-55. doi: 10.1006/mvre.1999.2163.
The purpose of this study was to elucidate the mechanism by which bradykinin (BK) enhances prostacyclin (PGI(2)) production in human umbilical vein endothelial cells (HUVEC). BK-induced enhancement of PGI(2) synthesis was observed in a dose- and time-dependent manner, and it also increased Ca(2+) followed by enhancement of cytosolic phospholipase A(2) (cPLA(2)) activity. The PKC inhibitors GF109203X and H7 attenuated the BK-induced increase in Ca(2+) and inhibited the BK-induced PGI(2) synthesis. Phorbol 12-myristate 13-acetate increased cPLA(2) activity and PGI(2) synthesis but failed to alter Ca(2+). BK increased cPLA(2) mRNA eightfold by 15 min, and this increase was inhibited by pretreatment with the PKC inhibitors. In response to cycloheximide pretreatment, cPLA(2) mRNA was superinduced. These results suggest that BK stimulates PGI(2) synthesis in HUVEC by activation of cPLA(2) by dual mechanisms: an elevation of Ca(2+) and a PKC-dependent pathway. Moreover, changes in calcium kinetics and expression of cPLA(2) mRNA may underlie the BK-induced PGI(2) enhancement in these cells.
本研究的目的是阐明缓激肽（BK）增强人脐静脉内皮细胞（HUVEC）中前列环素（PGI₂）生成的机制。观察到BK诱导的PGI₂合成增强呈剂量和时间依赖性，并且它还增加了细胞内钙离子浓度（[Ca²⁺]i），随后增强了胞质磷脂酶A₂（cPLA₂）的活性。蛋白激酶C（PKC）抑制剂GF109203X和H7减弱了BK诱导的[Ca²⁺]i升高，并抑制了BK诱导的PGI₂合成。佛波酯增加了cPLA₂活性和PGI₂合成，但未能改变[Ca²⁺]i。BK在15分钟内使cPLA₂ mRNA增加了八倍，并且这种增加被PKC抑制剂预处理所抑制。响应于放线菌酮预处理，cPLA₂ mRNA被超诱导。这些结果表明，BK通过双重机制激活cPLA₂来刺激HUVEC中的PGI₂合成：[Ca²⁺]i升高和PKC依赖性途径。此外，钙动力学的变化和cPLA₂ mRNA的表达可能是BK诱导这些细胞中PGI₂增强的基础。
