Mechanism of Oxygen Deficit. ∗

Abstract

Summary

In muscular exercise, a considerable oxygen deficit is incurred which cannot be explained by the accumulation of lactic acid. The hypothesis that this deficit is due to depletion of high energy phosphate in muscle and that the oxygen consumption is increased by an increase in phosphate acceptor was tested in the perfused dog gastrocnemius. Oxygen deficit was calculated from change in lactic acid and high energy phosphate after 2 minutes contraction. Oxygen deficit was calculated from oxygen consumption determined at 5-second intervals by measurement of blood flow and arteriovenous difference. For exercise, the muscle was stimulated at 300 cycles/second for 1-second intervals with 1 second rest. In 14 experiments, the average values of lactic acid were 14.2 mg % at rest, and 29.2 mg % during stimulation. The calculated deficit was 2.3 cc O₂/100 g muscle, and the measured deficit was 2.2 cc O₂/100 g muscle.