FACTORS IN VARIATION AND REGULATION OF CORONARY BLOOD FLOW IN INTACT ANESTHETIZED DOGS

Abstract

Coronary blood flow was detd. by the nitrous oxide method in 30 anesthetized dogs, and the findings were correlated with a number of observations on cardiovascular function simultaneously obtained during right ventricular catheterization. Even under controlled conditions, a large variation in data was noted in 13 dogs re-examined at an interval of 3-4 weeks. On single detn., high degrees of correlation were found between coronary blood flow and cardiac oxygen consumption (r=0.879 in 30 observations, and 0.900 in 60 observations), suggesting a metabolic-regulating mechanism for coronary blood flow. A high degree of correlation was also observed between coronary blood flow and cardiac rate (r=0.700), cardiac output (r=0.742) and cardiac work (r=0.775). For dogs (14-33 kg.), the following data may be regarded as normal values under Dial-urethane pentobarbital anesthesia: coronary blood flow, 85 cc/100 g./min.; cardiac oxygen consumption, 9.3 cc/100 g./min.; cardiac output, 2.85 cc./min.; peripheral resistance 3010 units; coronary resistance, 1.32 (ratio of coronary flow to arterial pressure); coronary atrioventricular oxygen difference, 11.4 volumes %; coronary oxygen utilization 69%. Dial anesthesia in morphinized dogs appeared to simulate a resting circulatory state; pentobarbital Na anesthesia produced a situation comparable to moderate exercise.