Oxidative phosphorylation and aspects of calcium metabolism in myocardia of hypercholesterolaemic swine with moderate coronary atherosclerosis.

Aspects of myocardial oxidative phosphorylation and Ca2+ metabolism were studied in a swine model in which coronary atherosclerosis was induced by a combination of denudation of the endothelium of the coronary arteries plus 7--11 months of feeding a high fat--high cholesterol diet. By microscopy, a moderate amount of coronary atherosclerosis was present at the time of sacrifice, and 2 of the 14 swine hearts had old myocardial infarcts. Myocardial mitochondria from grossly normal areas showed partial uncoupling and decreased state 3 O2 uptake with 3 of 4 substrates tested. In addition, Ca2+ stimulated mitochondrial respiration was decreased in the atherosclerotic swine. In the sarcoplasmic reticulum Ca2+ uptake under conditions of heavy loading was greater in the atherosclerotic swine than in control animals. The degree of atherosclerosis was not great enough to suggest that persistent myocardial ischaemia was present. Possibly coronary artery spasm induced an intermittent ischaemia resulting in the metabolic abnormalities observed, or the changes may have been brought about by the effects of the high fat--high cholesterol diet on subcellular membranes.