The effects of dibutyryl cyclic AMP, theophylline and papaverine on the release of 3H-catecholamines from rat brain striatal and cortical synaptosomes.

Papaverine enhances the spontaneous release of 3H-dopamine from rat brain striatal synaptosomes and 3H-noradrenaline from cortical synaptosomes in a dose-dependent way. Neither dibutyryl cyclic AMP nor theophylline had any significant effect on either spontaneous or on potassium-evoked 3H-catecholamine release. It is suggested that the effect of papaverine on catecholamine release is not due to its phosphodiesterase inhibitory potency.