THE RÔLE OF GLYCOGEN IN THE CONTRACTION OF THE PERFUSED HEART OF THE RABBIT

Abstract

The unperfused hearts of 21 rabbits starved 3-6 days and subjected to convulsions from strychnine (to exhaust the glycogen) contained 0.06%-0.25% (av. 0.12%) glycogen. The hearts of 10 rabbits not subjected to strychnine convulsions (3 well fed, 7 starved 3 days) perfused with glucose-free Ringer-Locke''s solution showed a glycogen content (0.03-0.13%, av. 0.094%) much below that in 7 normal rabbits starved for 3 days (0.33-0.50%, av. 0.40%). The hearts of 4 rabbits containing traces (less than 0.1%) of glycogen and perfused identically had approximately the survival period of about 4 hrs. The consumption of energy of the perfused heart is believed to be sufficiently great so as to preclude the possibility that hearts deficient in glycogen can obtain their energy from the oxidation of the remaining traces of this substance. It would appear from these observations that when glycogen is present in a heart, it is used by preference, but that when it is gone, some other foodstuff can serve as a source of energy. The value of glucose in the perfusing fluid for the heart is considered. On the basis of the authors'' observations, it is suggested that the beneficial effect of glucose is not due to the fact that it is converted into glycogen.