[Effect of oxyphenamone, a new inodilator, on isolated cardiac muscles and arteries].
The cardiotonic and vasodilating effects of oxyphenamone were studied in preparations of rat Langendorff's heart, isolated cardiac muscles of guinea pigs and isolated arteries of dogs. In the preparations of rat Langendorff's heart, infusion of oxyphenamone at 0.1 and 1.0 mumol.L-1 increased myocardial contractility and coronary blood flow moderately and decreased heart rate slightly. Oxyphenamone (1-100 mumol.L-1) increased the contractile force of papillary muscle (PM) and left atrium (LA) of guinea pigs dose-dependently. The positive inotropic effect of oxyphenamone (the ED50 was found to be 18.35 mumol.L-1 in PM and 9.17 mumol.L-1 in LA) was close to that of milrinone, an inhibitor of phosphodiesterase(the ED50 was shown to be 6.23 mumol.L-1 in PM and 4.59 mumol.L-1 in LA). The difference between these two agents is that oxyphenamone decreased the spontaneous pulse rate of right atrium, while milrinone increased it. The vasoconstrictions of dog coronary, basilar and mesenteric arteries induced by KCl, 5-HT and CaCl2 were antagonized non-competitively by oxyphenamone at 1 and 50 mumol.L-1, suggesting that oxyphenamone has a relaxant effect on vascular smooth muscles.
Fan
L L
LL
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100050.
Sun
L H
LH
Lin
Y
Y
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009930:Organic Chemicals; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
D002316:Cardiotonic Agents; D009930:Organic Chemicals; D014665:Vasodilator Agents; C442156:oxyphenamone