Effects of a cardiotonic agent, TA-064, on isolated canine cerebral, coronary, femoral, mesenteric, and renal arteries.
We investigated the effects of a newly synthesized cardiotonic agent, TA-064, on helical strips of isolated canine cerebral, coronary, femoral, mesenteric, and renal arteries. TA-064 had no effect on isolated arterial strips under resting tension. When the arterial strips were partially contracted with prostaglandin F2 alpha, TA-064 caused markedly significant concentration-related relaxations in coronary arterial strips. However, the maximum relaxation induced by TA-064 in renal, mesenteric, and femoral arterial strips was only one-third or less of the coronary artery. On the other hand, cerebral arterial strips generated negligible responses to TA-064. Relaxation of renal, mesenteric, and femoral arteries was not potentiated by pretreatment with 10(-5) M phenoxybenzamine. The concentration-response curve for TA-064 in coronary artery was shifted to the right to a similar extent by exposure to 2 X 10(-7) M propranolol and 2 X 10(-7) M metoprolol. On the other hand, relaxation of renal arterial strips was only slightly attenuated by metoprolol but was inhibited by propranolol. Droperidol (3 X 10(-5) M) failed to significantly alter the concentration-response curve for TA-064 in coronary artery. These results indicate that TA-064 causes coronary arterial vasodilatation mediated by beta 1-adrenoceptors. It would further appear that the same mechanism may be responsible for the positive inotropic action of TA-064.
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002536:Cerebral Arteries / Q000502:physiology; D003331:Coronary Vessels / Q000502:physiology; D004285:Dogs; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D005263:Femoral Artery / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000502:physiology; D012077:Renal Artery / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
D002316:Cardiotonic Agents; D004983:Ethanolamines; C037293:denopamine