ASPHYXIAL ARREST OF THE ISOLATED RABBIT'S AURICLE

¹ The Departments of Pharmacology and Physiology, University of Edinburgh

1. Under asphyxial conditions, normal mechanical activity of the rabbit's auricle is not maintained for longer than a few minutes even when the conditions are most favourable for glycolysis, the mechanical activity and the phosphagen index seem to fall together, it is therefore suggested that phosphagen breakdown rather than glycolysis energises the contraction of the rabbit's auricle.

2. At asphyxial arrest the glycogen content of rabbit's auricle is reduced to two-thirds and the phosphagen content to one-third of their normal value.

3. Poisoning with I.A.A. produces changes in the response of the rabbit's auricle to asphyxia essentially similar to those observed with the frog's heart.

The writer gratefully acknowledges his indebtedness to Professor A. J. Clark for his suggestions and advice throughout the experiments. Acknowledgment is also due to Dr. P. Eggleton and Dr. A. Deutsch for their kind help in connection with the chemical techniques employed.

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