Effect of (+)-amphetamine on the retention of 3H-catecholamines in slices of normal and reserpinized rat brain and heart.

The effect of reserpine on the inhibition by (+)-amphetamine and cocaine of the accumulation of 3H-dopamine (DA) in striatal slices and 3H-noradrenaline (NA) in slices of cerebral occipital cortex and heart atrium of rats and the release of 3H-amines from these tissues were examined. Reserpine (5 mg/kg intraperitoneally) was injected 18 hours before the experiments. It was found that reserpine markedly enhanced the in vitro potency of amphetamine in the striatum and heart but only slightly in the cortex. After administration in vivo (+)-amphetamine was about 10 time more potent in reducing the amine accumulation in the cortex as in the striatum. Reserpine enhanced the effect in both regions. The inhibitory potency of cocaine in vitro was unchanged by reserpine in the striatum but was reduced in the cortex and heart. Reserpine did not change the inhibitory potency of desipramine in the cortex and heart. The release of the 3H-amines by (+)-amphetamine was enhanced by reserpine in the striatum and heart but the small release produced in the cortex was not increased. The release produced by cocaine was similarly enhanced by reserpine but cocaine was much less active than (+)-amphetamine. The results indicate that (+)-amphetamine and cocaine inhibit the amine accumulation by different mechanisms.