Effect of Reserpine on the Release of Catecholamines from Isolated Nerve and Chromaffin Cell Granules

In a suspension of bovine splenic nerve granules, reserpine in concentrations of 10‐8‐10‐5 M strongly inhibits the spontaneous release of noradrenaline. The catecholamine releasing action of tyramine on nerve granules is unaffected by low concentrations of reserpine, but is almost completely blocked by concentrations of 10‐5 M. Reserpine is less active as inhibitor on suprarenal medullary granules from the rabbit and still less on cats' medullary granules. The spontaneous release occurs at a lower rate in rabbit's medullary granules than in those from the cat. No difference in the rate of release was found between adrenaline and noradrenaline from the cat's medullary granules. After administration of dopa 100 mg/kg i.v. in the rabbit the rate of release from the medullary granules was greatly enhanced. The possible action of reserpine as enzyme inhibitor is briefly discussed.