Aortic respiration and glycolysis in the pre-proliferative phase of diet-induced atherosclerosis in swine

Cholesterol or stock diets were fed to fourteen pairs of miniature swine for periods varying from 3 to 112 days. Measurements of respiration, aerobic and anaerobic net lactic acid production and lipid content were done in grossly normal intima-media from the upper thoracic aorta in both dietary groups. Intima-media respiration was significantly higher per unit of DNA in the cholesterol-fed swine than in stock-fed swine. This was so even before any grossly visible atherosclerotic lesions were apparent and before there was any light microscopy or biochemical evidence of cell proliferation, but when pre-proliferative changes were presumably present. The aerobic and anaerobic net lactic acid production however were the same in the aortic tissue of both the cholesterol and stock-fed groups. Both total cholesterol and phospholipid were increased in concentration in the grossly normal intima-media after 44 days of feeding the cholesterol diet. The increased tissue respiration before the appearance of atherosclerotic lesions characterized by smooth muscle cell proliferation may mean that the intima media of the swine is synthesizing more ATP or high energy intermediates. That there might be an increased demand for energy in the artery associated with cholesterol diets in swine is suggested by electron microscopy and autoradiographic studies of the pre-proliferative phase of cholesterol-induced atherosclerosis in the same animals as were used in this experiment.