Nature of the antiadrenergic properties of an indolizine.
Inhibition by 2-ethyl-3-(4-y-di-n-butylaminopropoxybenzoyl)-indolizine hydrochloride (L 9394) and by propranolol of the positive chronotropic effect of isoproterenol on spontaneously beating rabbit right atria has been studied in vitro. Propranolol behaved like a typical competitive beta 1-adrenoceptor antagonist with a pA2 value of 8.33. L 9394 acted as a non-competitive inhibitor with a pD'2 value of about 4.98. Inhibition by L 9394 and phentolamine of the norepinephrine-induced contractions of isolated rat aortic strips has been studied likewise. Phentolamine inhibited the adrenergic alpha-adrenoceptor competitively with a pA2 value of 8.69 while L 9394 behaved like a dual inhibitor, with a competitive component (pA2 value of 6.35) and a non-competitive component (pD'2 value of about 4.72).
D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D004347:Drug Interactions; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007212:Indolizines / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D009467:Neuromuscular Depolarizing Agents; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D013565:Sympatholytics
D001565:Benzoates; D007212:Indolizines; D009467:Neuromuscular Depolarizing Agents; D013565:Sympatholytics; D011188:Potassium; D009638:Norepinephrine