In vitro release of 3H-noradrenaline by amphetamine from the superior cervical ganglion of the cat.

Abstract

The release and metabolism of 3H-noradrenaline (3H-NA) produced by d-amphetamine was studied in the superior cervical ganglion of the cat (cell bodies) and in the nictitating membrane (nerve endings). Exposure of the nictitating membrane to 10 microM d-amphetamine, resulted in the release of 5.1% of the total radioactivity. This was mainly collected as 3H-normetanephrine (3H-NMN) and as 3H-NA; 3H-3,4-dihydroxyphenylglycol (3H-DOPEG) did not contribute to the drug-induced outflow of radioactivity. In contrast, exposure of ganglionic cell bodies to 10 microM d-amphetamine for 10 min released only 1.74% of the total tissue radioactivity and 3H-DOPEG represented the most important fraction of the released radioactivity. When ganglia were exposed to 30 microM d-amphetamine, the radioactivity released was 5.2%; the proportion of 3H-NA and 3H-NMN increased and 3H-DOPEG was reduced. These results show that: a) d-amphetamine releases 3H-NA from prelabeled cell bodies and nerve endings; b) the potency of d-amphetamine was higher in nerve terminals than in cell bodies, and c) at low concentrations of d-amphetamine, the metabolism of the released neurotransmitter differed between both parts of the adrenergic neuron.