Coronary vasoconstriction by locally administered acetylcholine, carbachol and bethanechol in isolated, donor-perfused, rat hearts.
1 Experiments were carried out on rat isolated heart preparations in which the coronary vasculature was perfused through the aorta at a constant flow rate with arterial blood from donor animals. Single doses of drugs were injected into the aortic cannula. 2 Small doses of acetylcholine, carbachol or bethanechol decreased perfusion pressure (PP) without markedly affecting left ventricular pressure (LVP) and heart rate (HR); larger doses of these drugs increased PP (vasoconstriction), and decreased LVP and HR in a dose-dependent manner. 3 Acetylcholine, carbachol and bethanechol had almost no effects when perfused through the aorta in such a way as to exclude the coronary vessels. 4 Coronary vasoconstriction in response to acetylcholine, carbachol and bethanechol was not significantly affected by reserpine pretreatment, phentolamine or hexamethonium, but was antagonized by small doses of atropine. 5 From these results it is concluded that in the coronary vasculature of the rat, the receptors involved in the vasoconstrictor actions of acetylcholine carbachol and bethanechol are muscarinic.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001626:Bethanechol Compounds / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects*; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D012110:Reserpine / Q000494:pharmacology; D013045:Species Specificity; D014662:Vasoconstrictor Agents
D001626:Bethanechol Compounds; D014662:Vasoconstrictor Agents; D012110:Reserpine; D002217:Carbachol; D000109:Acetylcholine