Metabolic responses during myocardial reactive hyperemia in the unanesthetized dog

¹ Department of Cardiorespiratory Diseases, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, D. C.
² Department of Cardiorespiratory Diseases, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, D.C.

Studies of myocardial metabolism during reactive hyperemia in unanesthetized dogs reveals that A-V oxygen difference is consistently decreased during reactive hyperemia. Myocardial oxygen consumption rate is increased, however, as the increase in coronary blood flow rate is greater than the decrease in A-V oxygen difference. Oxygen debt is always, though variably, overpaid. Studies of A-V lactate and pyruvate differences show that occlusions of more than 6 sec regularly lead to lactate production, while occlusions shorter than this do not. It is suggested that myocardial reactive hyperemia is a metabolic response to a metabolite produced by even mild degrees of anoxia. The effects of this metabolite on coronary blood flow appear to be out of proportion to the anoxic stimulus.

Key Words: coronary flow • electromagnetic flowmeter • coronary occlusion • myocardial metabolism • oxygen debt

Submitted on June 22, 1964

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