Mechanical Response of the Isolated Mammalian Heart to Anoxia. ∗

Abstract

Conclusions

1. The depressant effects of anoxia on the completely isolated mammalian heart appeared at oxygen tensions well below those tolerated by the intact animal. The heart muscle, therefore, at least as examined in the present experiments, cannot be regarded as a limiting factor in tolerance of the intact animal for anoxia. 2. Increases in cardiac output (of purely cardiac origin) by the isolated heart under anoxia are seen only when C0₂ is absent from the ventilating gas. The effect appears to be due to the marked elevations in pH seen under these conditions, and, as such, is regarded as a systematic artefact rather than evidence of a direct stimulating effect of low oxygen tensions on the myocardium.