title: Dopamine agonist properties of N-alkyl-4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinolines.
abstract: A series of homologous N-alkyl-4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinolines was synthesized and examined for a dopamine-like ability to dilate the renal artery. The N-methyl derivative was equipotent to the 3',4'-dihydroxy derivative of the antidepressant agent nomifensine, indicating that the 8-amino group of the latter is not essential for dopamine-like activity. The N-ethyl homologue was reduced in potency when compared to the N-methyl, and the N-n-propyl, surprisingly, was essentially devoid of activity. This was unexpected in view of the fact that in all series of dopamine-like agents reported to date, N-alkylation, when one of the alkyls was an n-propyl group, either allowed retention or enhancement of potency.
mesh_terms: D000818:Animals; D004285:Dogs; D018492:Dopamine Antagonists; D004353:Drug Evaluation, Preclinical; D007546:Isoquinolines / Q000138:chemical synthesis / Q000494:pharmacology*; D008297:Male; D009627:Nomifensine / Q000031:analogs & derivatives; D012077:Renal Artery / Q000502:physiology; D014665:Vasodilator Agents; D014666:Vasomotor System / Q000187:drug effects
chemical_list: D018492:Dopamine Antagonists; D007546:Isoquinolines; D014665:Vasodilator Agents; D009627:Nomifensine