Inhibition by lidoflazine of the contractile response of the rat isolated colon to angiotensin.
1. In the rat isolated ascending colon, lidoflazine in a concentration of 5 x 10(-7)M slightly enhanced the response to angiotensin, but in a concentration of 10(-6)M it was a strong and unsurmountable antagonist.2. Exposure to lidoflazine (10(-6)M) also inhibited the contractile responses to acetylcholine, 5-hydroxytryptamine and barium ions. The antagonism of acetylcholine and 5-hydroxytryptamine was unsurmountable and quantitatively similar to that of angiotensin. The antagonism of barium ions was much weaker and probably competitive.3. The inhibitory effect of papaverine (10(-5)M) showed a pattern similar to that found for lidoflazine.4. It is concluded that the antagonism of angiotensin by lidoflazine in the rat colon is non-specific.
D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000804:Angiotensin II / Q000037:antagonists & inhibitors*; D000818:Animals; D001464:Barium / Q000037:antagonists & inhibitors; D003106:Colon / Q000187:drug effects; D004357:Drug Synergism; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010208:Papaverine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology*; D051381:Rats; D012702:Serotonin Antagonists; D014665:Vasodilator Agents / Q000494:pharmacology*
D010879:Piperazines; D012702:Serotonin Antagonists; D014665:Vasodilator Agents; D000804:Angiotensin II; D001464:Barium; D010208:Papaverine; D000109:Acetylcholine