Relationship of pyruvate and lactate during anaerobic metabolism. IV. Local tissue components of total body O2-debt

Abstract

In anesthetized dogs breathing 10% oxygen, anaerobic metabolic rate (AMR) of the body was measured as the rate of accumulation of ‘excess lactate’ (XL) in ‘mixed venous’ blood and appeared as a smooth, progressively rising curve. However, AMR was very variable in individual regions of the body, varying both with location and with time. The only predictable feature of these patterns was the tendency toward a constant sum. This feature suggested that the irregular distribution of AMR in various local areas was a manifestation of the manner in which the cardiac output was distributed in the body from one time to another, a hypothesis consistent with the theoretical biochemical significance of XL. Lactate exchanges of local tissues did not appear to be related to O₂-debt, but the summation of XL exchanges gave a satisfactory approximation of O₂-debt. It was concluded that measurements of oxygen, even of oxygen-debt of the body, give no indication of the adequacy of oxygen supply to any individual region of the body, and conversely that study of a local venous blood is unlikely to give an accurate representation of the body as a whole.