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

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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.