SUPPRESSION OF AGONIST-INDUCED CA2-HEPATOCYTES BY NAFENOPIN - POSSIBLE INVOLVEMENT OF PROTEIN-KINASE-C( OSCILLATIONS IN CULTURED)

The alpha(1)-agonist phenylephrine (5 mu M) induces an increase in the free cytosolic Ca2+ concentration, followed by repetitive transients of the cytoplasmic Ca2+ concentration, in Single Fura-2 loaded hepatoc ytes. The tumor promoting, hypolipidemic drug nafenopin suppressed the cellular Ca2+ response to phenylephrine. The effect of nafenopin on t he Ca2+ increase and Ca2+ oscillations was largely prevented by the sp ecific protein kinase C inhibitor Go 6976. This finding suggests invol vement of protein kinase C in the action of nafenopin on phenylephrine induced Ca2+ mobilization.