Some factors influencing O₂ consumption of isolated heart muscle

¹ Department of Physiology, University of California School of Medicine, Los Angeles, California

Oxygen consumption and resting and developed tension in isolated strips of mammalian myocardium were simultaneously measured in specially constructed chambers. In a resting preparation the O₂ consumption increased significantly as the length of the muscle was increased. The evidence suggests that the augmented Qo₂ (µl/mg dry wt/hr.) is largely a result of the lengthening, per se, and is not due to the maintenance of tension. In the beating preparation, variations in rate and length accounted for most of the change in the O₂ uptake, tension being a less significant factor. The possible relationship of these findings to ‘Starling's law of the heart’ is discussed.

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