ALPHA(1)-ADRENERGIC AND 5-HT2-SEROTONERGIC EFFECTS OF SOME BETA-ALKOXY-BETA-PHENYLETHYLAMINES ON ISOLATED RAT THORACIC AORTA

1. Ten racemic beta-alkoxy-beta-phenylethylamines were found to elicit concentration dependent contraction of the isolated rat thoracic aort a with apparent pD(2) values in the 4.56-6.76 range. With one exceptio n, which produces the same maximal contraction (E-max) as serotonin (5 -HT), the E-max values attained with these compounds are lower than th ose produced by either 5-HT or norepinephrine (NE). 2. Pretreatment wi th either prazosin or ketanserin (10(-8) M) leads in most cases to dec reased E-max values and slopes in the dose-response curves. Apparent s erotonergic (pD(2)(S)) and adrenergic (pD(2)(A)) pD(2) values going fr om 4.22 to 6.08 (pD(2)(S)) and from 3.87 to 5.27 (pD(2)(A)) were calcu lated from results obtained in the presence of prazosin or ketanserin, respectively. 3. In the 10(-7)-10(-5) M range, and in contrast with t he results obtained with the previous compounds, BON 2,5-dimethoxy-4-n itrophenyl)-2-methoxy-ethylamine] behaves as an antagonist to both 5-H T and NE (apparent pA(2)=7.08 and 7.45, respectively) in this preparat ion. (C) 1998 Elsevier Science Inc.