The mechanism of bradykinin-induced arachidonic acid release in osteoblast-like MC3T3-E1 cells phospholipase A2 activation by bradykinin and its regulation by protein kinase C and calcium
Suzuki, N.; Matsunaga, T.; Kanaho, Y.; Nozawa, Y.
Nihon Seikeigeka Gakkai Zasshi 67(10): 935-943
1993
ISSN/ISBN: 0021-5325 PMID: 8263365 Document Number: 415167
In the present study, we investigated the mechanism by which bradykinin (BK) enhances [3H]arachidonic acid release in murine osteoblast-like MC3T3-E1 cells prelabeled with [3H]arachidonic acid. BK enhanced [3H]arachidonic acid release in a time- and concentration-dependent manner, when cells were stimulated in the presence, but not in the absence, of extracellular Ca2+. It appears that the BK-induced [3H]arachidonic acid release was attributed to the activation of phospholipase A2, since a phospholipase A2 inhibitor, mepacrine, significantly inhibited the BK enhancement of [3H]arachidonic acid release whereas a diacylglycerol lipase inhibitor, RHC80267, failed to do so. Furthermore, it was found that a protein kinase C inhibitor, staurosporine, and down-regulation of protein kinase C by prolonged exposure of cells to phorbol 12-myristate 13-acetate inhibited the BK-induced [3H]arachidonic acid release. These results provide evidence that BK stimulation of MC3T3-E1 cells activates phospholipase A2 to liberate arachidonic acid by the mechanism which involves both Ca2+ and protein kinase C.