EFFECTS OF 2 ANALOGS OF DOPAMINE ON GANGLIONIC TRANSMISSION IN THE SYMPATHETIC NERVOUS-SYSTEM

Abstract

Two aminotetralin analogs of dopamine were studied for their effects on ganglionic transmission in the [cat] sympathetic nervous system. Nerve activity (spontaneous firing or evoked action potentials) was recorded on a preganglionic nerve (splanchnic), a mixed nerve (lumbar chain) and several postganglionic nerves (external carotid branch and renal nerve). 6,7-Dihydroxy-2-dimethylaminotetralin and 5,6-dihydroxy-2-dimethylaminotetralin were observed to markedly inhibit spontaneous firing in the renal nerve, external carotid branch and lumbar chain. Splanchnic nerve activity was unaltered. 6,7-Dihydroxy-2-dimethylaminotetralin also depressed evoked responses to submaximal stimulation in the external carotid branch and lumbar chain. These results suggest a ganglionic site of action. Since functional vasomotor activity in the isolated perfused canine forelimb in response to preganglionic nerve stimulation was unaltered, 6,7-dihydroxy-2-dimethylaminotetralin may depress transmission only at certain ganglionic pathways.