STIMULATION OF RAT-LIVER MICROSOMAL CGMP-INHIBITED CAMP PHOSPHODIESTERASE (PDE-III) BY PHOSPHOLIPASE-C AND PHOSPHOLIPASE-D

The specific activity of cGMP-inhibited cAMP phosphodiesterase (PDE III) of rat liver microsomal membranes is increased in a concentration-dependent way by adding phospholipase C from Clostridium perfringens or phospholipase D from Streptomyces chromofuscus. The effect depends on an increase in Vmax of the enzyme. Treatment of microsomal membranes with phospholipase C causes a marked increase in the relative amounts of phosphatidylserine and phosphatidylinositol, and mild stimulation of PDE III activity. Treatment with phospholipase D increases phosphatidic acid and strongly increases PDE III activity. These data suggest that phosphatidic acid is the most important regulator of membrane-bound PDE III activity in liver. © 1993 Academic Press. All rights reserved.