BRADYKININ INCREASES INTRACELLULAR FREE CA2-SECRETION IN THE CLONAL BETA-CELL LINE, HIT-T15( CONCENTRATION AND PROMOTES INSULIN)

We have examined the effects of bradykinin (BK) on both the intracellu lar free calcium concentration ([Ca2+](i)) and insulin secretion in th e hamster beta-cell line, HIT-T15 cells. BK evoked a rise in [Ca2+](i) in a dose-dependent manner. This response was suppressed by neomycin, suggesting that BK mobilizes Ca2+ from intracellular store via promot ion of the phosphatidyl inositol turnover. Furthermore, BK also evoked insulin secretion. Both the BK-evoked rise in [Ca2+](i) and insulin s ecretion were suppressed by the BK2 receptor antagonist, but not by th e BK1 receptor antagonist. These results indicate that BK increases [C a2+](i) via BK receptor, thereby promoting insulin secretion in HIT-T1 5 cells. (C) 1996 Academic Press, Inc.