Reflex parasympathetic coronary vasodilation elicited from cardiac receptors in the dog.
Veratrum alkaloids injected into the coronary circulation stimulate myocardial receptors to produce reflex bradycardia and arterial hypotension (the Bezold-Jarisch reflex). This study investigated the hypothesis that parasympathetic coronary vasodilation occurs as part of the Bezold-Jarisch reflex. Blood flow in the circumflex coronary artery was measured in chloralose-anesthetized, closed-chest dogs with a newly developed cannula-tip flow transducer. Alpha-receptor blockade with Dibozane (2 mg/kg) was used to prevent peripheral vasodilation, and beta-receptor blockade with propranolol (1 mg/kg) was used to prevent adrenergic cardiac effects. Electrical pacing was used to maintain a constant heart rate. Under these conditions, veratridine injected into the anterior descending coronary artery but not into the circumflex coronary artery produced a 63% increase in circumflex coronary blood flow and an 88% increase in diastolic coronary conductance. The effect was abolished when the reflex arc was interrupted by either vagotomy or atropine administration. It is concluded that a cardiocoronary reflex parasympathetic coronary vasodilation can be elicited by stimulating cardiac receptors with veratridine.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000209:etiology; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects / Q000294:innervation*; D004285:Dogs; D004562:Electrocardiography; D006321:Heart / Q000187:drug effects / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption; D010138:Pacemaker, Artificial; D010275:Parasympathetic Nervous System / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D012018:Reflex; D012131:Respiratory Insufficiency / Q000209:etiology; D014630:Vagus Nerve / Q000502:physiology; D014666:Vasomotor System; D014701:Veratridine / Q000494:pharmacology
D014701:Veratridine; D011433:Propranolol