Changes in esterified fatty acids in the isolated, perfused rabbit heart

Abstract

The hearts of fasted (48 h) or fed rabbits were perfused with buffer solution with or without glucose. The right ventricle was removed at the 10th min of perfusion. The left ventricle was perfused for 10, 70, or 130 min. Cardiac lipids were analyzed by the hydroxamic acid method and gas chromatography. The neutral lipid fraction from the heart of the fasted rabbit contained relatively more linoleic and less palmitic acid than that from the heart of the fed animal. Similarly, relatively more oleic and less stearic acids were found in the phospholipid fraction from the heart of the fasted rabbit. There was a slight difference in fatty acid distribution between the right and left ventricular lipids at the 10th min of perfusion.The left ventricle of the fasted rabbit lost two-thirds of its neutral lipid stores during perfusion for 120 min with a substrate-free medium. Some of the phospholipid also disappeared between the 70th and the 130th min of perfusion. No measurable loss of lipids was found in the hearts of fed animals perfused under the same conditions. In the presence of glucose in the perfusing medium, cardiac lipid contents remained unchanged during perfusion regardless of the nutritional state of the animal. Esterified fatty acid composition did not change significantly during perfusion. The significance of these observations is discussed in relation to possible metabolic control systems in fasted and fed animals.