The oxygen uptake of frozen and thawed muscles

In connection with the chemical changes which muscle undergoes on freezing and thawing (Smith, 1929; Smith and Moran, 1930), it appeared of interest to determine the degree of injury suffered by the respiratory mechanism of the muscle as a result of freezing. It was hoped, in particular, that some light might be thrown on the nature of the injury to the machinery involving the synthesis of glycogen from lactic acid, since in this process the energy for the building up of the greater part of the lactic acid is derived from the oxidation of a smaller fraction. A muscle frozen for 24 hours at –1⋅6° C. and then thawed is found to have lost this faculty of oxidative synthesis. The breakdown of the synthetic mechanism might be due to the destruction of the mechanism of oxidation, of the actual synthetic enzyme, or of the coupling mechanism by which the energy of the former reaction is made available for the process of synthesis. The first possibility could be tested by actual experiment, and major part of this paper gives the results of experiments made with this end in view. In addition, some measurements of the respiration of muscles actually in the frozen state have been made. As might be expected, the oxygen uptake gradually diminishes with falling temperature. There is no sign of any sudden change in the neighbourhood of the critical temperature which might be associated with the change in behaviour of the muscle with respect to the carbohydrate metabolism.