Experiments on muscle haemoglobin in vivo ; the instantaneous measurement of muscle metabolism

Abstract

Muscle haemoglobin is fitted to act both as a short-time oxygen store and as an intracellular indicator of oxygen tension, with an “indicating time” of less than one-hundredth of a second (R. Hill 1936; Millikan 1936). We can now measure its rate of oxygenation and reduction in a normal muscle, during rest and contraction, both with unimpaired and arrested circulation, and are thus enabled: (1) to obtain direct evidence about the function of muscle haemoglobin in the living tissue; (2) to measure the instantaneous oxygen consumption before, during, and after contraction; (3) to determine the minimum intracellular oxygen tension at which normal muscle can operate; hence the substrate-enzyme affinity of the “limiting” oxidation enzyme; and (4) from the rate of oxygen supply to follow changes in the rate of blood flow during and after muscular contraction.