Bradykinin stimulated PGE2 production is independent of changes in intracellular calcium in MDCK cells

In order to assess whether changes in intracellular Ca2+ are necessary for bradykinin stimulated activation of phospholipase A2 and PGE2 production, MDCK cells were treated with phorbol myristate acetate (PMA) and Lanthanum (La3+). 100nM PMA reduced peak BK (1uM) stimulated Ca2+ to 44.0 ± 11.4% of control, while 1mM LaCl3 reduced peak Ca2+ to 43.5 ± 12.2% of control. Addition of both PMA and LaCl3 reduced the BK stimulated change in intracellular Ca2+ to 8.3 ± 1.0% of control. In contrast, La3+ did not reduce PGE2 production in response to 10^-7M to 10^-5M BK. PMA stimulated PGE2 production, as shown previously. Addition of both PMA and La3+ at doses capable of reducing Ca2+ changes to less than 10% of normal, failed to block BK induced PGE2 production. Therefore, BK stimulated PLA2 activation and PGE2 production can be dissociated from changes in intracellular Ca2+ and suggest that BK activates PLA2 through a mechanism other than by increases in intracellular Ca2+.