Inhibition of calmodulin dependent c-AMP-phosphodiesterase by moxaverine and papaverine.

Vasodilator properties of papaverine and moxaverine have been attributed to an inhibition of cyclic adenosine monophosphate (c-AMP) phosphodiesterase (PDE). The discovery of the calmodulin (CaM) dependence of c-AMP PDE activity necessitates a reinvestigation of the molecular mode of action of papaverine-like compounds. Separately analyzing the inhibition of basal and CaM-stimulated enzyme activity by these drugs proves the preferred inhibition of the CaM stimulated c-AMP PDE. Lipophilicity is assumed to represent an indicator of CaM-inhibitory potency.