Cyclic AMP phosphodiesterase activation by the histamine releasing agent, compound 48/80

Abstract

Summary A kinetic analysis of the cyclic AMP phosphodiesterase activities of rat mast cell homogenate 8000 × g supernatant fractions was performed, revealing apparent Km values of 4 μM and 80 μM. Compound 48/80 caused a dose related increase in the activity of the high Km enzyme. In a 1 ug/ml solution of 48/80 (a concentration which causes marked histamine release and a rapid decrease in cAMP in intact mast cells), a four fold increase in high Km activity was observed. These findings suggest, but do not prove, that the 48/80 induced fall in cAMP may be mediated through this enzyme.