EFFECT OF ASPHYXIA ON THE ADENOSINETRIPHOSPHATE CONTENT OF THE RABBIT'S HEART

¹ Department of Pharmacology, University of Edinburgh

1. Asphyxia of the rabbit's heart in situ produced at the time of arrest a loss of three-quarters of its phosphagen, nine-tenths of its glycogen, and three-quarters of its adenosinetriphosphate content. The reduction of the three substances to their minimal value occurred in the following order: phosphagen, glycogen, and adenosinetriphosphate. Asphyxial arrest of rabbit's heart in situ can therefore be ascribed to depletion of available sources of energy.

2. When auricles asphyxiated to arrest in situ were revived in vitro phosphagen was rapidly restored to normal, but the restoration of adenosinetriphosphate was much slower and less complete.

3. As regards both asphyxial changes and changes during recovery after asphyxia, the mechanical activity and the phosphagen content varied in a similar manner. The changes in the adenosinetriphosphate content were slower and less extensive, and no close relation could be demonstrated between these latter changes and the changes in the mechanical response.

4. "Hexosemonophosphate" accumulated both during anaerobiosis in the normal heart and in the I. A. A. poisoned auricles under both aerobic and anaerobic conditions.

5. Auricles asphyxiated to arrest in situ, revived in oxygen in vitro and again asphyxiated responded to asphyxia like auricles poisoned with I. A. A., since they were arrested in two or three minutes and a "contracture" followed.

The writer gratefully acknowledges his indebtedness to Professor A. J. Clark for his suggestions and advice throughout the experiments.

The expenses of this research were partly defrayed by a grant from the Moray Research Fund of the University of Edinburgh, for which the writer wishes to express his thanks.