THE EFFECT OF GLYCINE UPON THE METABOLISM OF ISOLATED PERFUSED MUSCLE

Abstract

A preparation is described for studying the metabolism of an isolated hind leg in the dog, perfused with whole blood from another dog. The arterial and venous bloods of the preparation were analyzed for CO2 and O2 (method of Van Slyke and Neill), care being taken that the temp., blood flow and blood pressure should be constant for at least 15 min. before taking a sample. The O2 consumption of a resting group of muscles perfused with whole blood was between 0.0024 and 0.0093 cc. per gm. per min. In muscles perfused in this way the O2 consumption gradually diminished, reaching an average level at the end of 4 hrs. of about 35% below the original consumption. When 5 gm. of glycine were added to the perfusing blood, the O2 consumption, instead of falling as in the control muscles, rose markedly, this rise in 3 of the 4 experiments continuing for more than 3 hrs. It was shown that this increased oxidation was not due to (1) glycine supplying oxidizable material or (2) an increase in blood flow or in the O2 content of the arterial blood. The latter 2 factors bore no constant relationship to the amount of O2 consumption except in 1 case, when a very low blood flow and O2 content (5.46 vols. %) were apparently the cause of a falling metabolism. It is concluded that glycine acts as a powerful stimulator of the cell metabolism in an isolated perfused group of muscles. As a corollary to the above, it is concluded that the specific dynamic action of glycine is a direct effect on the cells of the tissue stimulated, and that no central control mechanism outside of the tissue need be postulated.