Protein kinase C modulates phospholipase C and increases arachidonic acid release in bradykinin stimulated MDCK cells.

The tumor promoter phorbol ester (PMA) has been shown to stimulate protein kinase C (PKC) in MDCK cells. At the concentrations that produce stimulation of PKC, PMA (100 microM) inhibits BK-induced I1,4,5P3 (IP3) formation and calcium transients in these cells. 1-5-isoquinolinyl-2-methyl-piperazine (H7) a known inhibitor of PKC in MDCK cells reverses the effect of PMA on BK-stimulated IP3 formation and Ca2+ transients in these cells. PMA also stimulates arachidonate release which can be inhibited by preincubation with H7. A dual mechanism of regulation by PKC at the level of phospholipase C (down regulation) and phospholipase A2 (stimulation) is suggested in these cells.