MODULATION OF FATTY-ACID-BINDING PROTEIN-CONTENT OF ADULT-RAT HEART IN RESPONSE TO CHRONIC CHANGES IN PLASMA-LIPID LEVELS

The aim of this work was to study in the adult rat heart the effect of modifications of fatty acid (FA) supply on the content of cytoplasmic fatty acid-binding protein (H-FABP(c)). To modify the amount of circu lating lipids, three different treatments were chosen: (i) an hypolipi demic treatment with Clofibrate, administered daily through a gastric tube at a dose of 250 mg/kg per day for one week, (ii) a continuous in travenous infusion of 20% Intralipid, a fat emulsion, for one week at a dose of 96 ml/kg per day, and (iii) a normobaric hypoxia exposure (P O2 = 10%) for three weeks. At the end of each treatment plasma lipids, myocardial H-FABP(c) content and the activities of three key enzymes (citrate synthase, CS, fructrose-6-phosphate kinase, FPK and hydroxy-a cyl CoA-dehydrogenase, HAD) were assessed. With each of the three trea tments a decrease of plasma cholesterol and phospholipid levels was ob served. Plasma FA concentration increased with Intralipid infusion and decreased with chronic hypoxia. The heart H-FABP(c) content was incre ased by 20% with Clofibrate, decreased by 20% with chronic hypoxia and remained unaltered upon Intralipid treatment. The induced changes in H-FABP(c) content were not related directly to changes in plasma lipid levels. CS activity was slightly decreased in the hypoxia group, FPK activity decreased in the Clofibrate group, and HAD activity decreased in the Intralipid group. Among the various groups heart H-FABP(c) con tent was related to HAD activity. In conclusion, the H-FABP(c) content of adult rat heart appears responsive to changes in plasma lipid leve ls.