Oxidative Phosphorylation in the Failing Dog Heart-Lung Preparation

Abstract

Utilizing dog heart-lung preparations mitochondria were obtained from control preparations and from hearts failing spontaneously, or as a result of pressure-loading or venous inflow-loading. The mitochondria were compared with respect to their oxidative phosphorylating capacity. The data on the P:O ratios indicate that there is an uncoupling of oxidative phosphorylation in the mitochondria from hearts in spontaneous failure, and in the mitochondria of hearts failing as a result of pressure-loading. In the case of failure due to venous inflow-loading of the heart the mitochondrial P:O ratios are within the control range. The data definitely support the conclusion that in certain types of failure in the dog heart-lung preparation the energy generating or liberating mechanisms may be impaired. This conclusion is contrary to that in the literature based on measurements of high-energy compounds and oxygen consumption, namely, that energy liberation, including transfer of oxidative energy in the form useful for contraction, is not impaired in the failing heart.