INHIBITION OF CANINE ADRENERGIC TRANSMISSION BY AN ANALOG OF DOPAMINE - GJH-166

  • 1 January 1977
    • journal article
    • research article
    • Vol. 202  (1) , 97-104
Abstract
The effect of GHJ-166 [trans-4-methyl-7,8-dihydroxy-1,2,3,4,4a,5,6,10b-octahydrobenzo (f) quinoline HBr], a potential dopamine agonist, on responses to adrenergic vasoconstrictor stimuli was studied in dogs. The hindlimb, gracilis muscle and spleen were isolated and perfused with arterial blood at constant flows. Nictitating membrane responses to adrenergic stimuli were also studied. I.v. GJH-166 injections in doses of 0.25-4.00 .mu./kg impaired responses to sympathetic nerve stimulation of the perfused hindlimb, gracilis muscle and spleen and inhibited nictitating membrane response. GJH-166 had a preferential inhibitory effect on responses induced by low frequency stimulation of nerves. Haloperidol antagonized the inhibitory effect of GHJ-166 on sympathetic transmission. The changes induced by norepinephrine at the perfused sites were not affected by the compound. Pressor responses to norepinephrine and tyramine were not inhibited by GJH-166. GJH-166 probably impairs sympathetic transmission by acting on certain inhibitory dopaminergic receptors located on the adrenergic nerve terminals.