Effect of reserpine on the subcellular distribution of 3H-alpha-methylnoradrenaline in the mouse heart.

1. Mice were injected with reserpine (0.5 mg/kg or 2.5 mg/kg) at various intervals after an intravenous injection of (3)H-alpha-methylnoradrenaline ((3)H-alpha-MeNa), 20 mug or 100 mug/kg. The effect of reserpine on the content of labelled amine in the subcellular fractions of the heart was studied.2. In most experiments reserpine caused a pronounced decrease in the (3)H-alpha-MeNA content of the particulate fraction (P). The decrease was most pronounced when the higher dose of reserpine and lower dose of alpha-MeNA were used. In most experiments, the (3)H-alpha-MeNA content of the supernatant fractions was unchanged and, therefore, the P/(P + S) ratio was decreased.3. It is concluded that the effect of reserpine is a releasing effect on the particulate (granular) fraction, probably by blocking the re-uptake of the amine leaked from the granules. No support was found for the hypothesis that reserpine acts by inhibition of release of amines from the nerve granules.