Abstract
1. 1. The possible regulation of endogenous lipid utilization by exogenous substrates was studied in a more physiological perfused working rat heart preparation. 2. 2. Rat hearts were isotopically prelabeled in vivo with [ 14C]palmitic acid and perfused in a closed recirculated system with bicarbonate buffer containing (a) no added substrates, (b) 5.5 mM glucose and/or (c) 0.7 mM or 1.3 mM palmitate. Content and 14C-labeling of triglycerides and phospholipids, 14CO 2 production, and tissue lipase activity of perfused heart homogenates were determined. 3. 3. In hearts perfused with buffer containing no substrate, or with added glucose, triglyceride content and 14C-labeling decreased 65% or more relative to initial values. This decrement in triglyceride labeling was recovered as 14CO 2. Exogenous palmitate decreased net triglyceride flux to 35% or less, with a concomitant reduction in 14CO 2 production. Heart phospholipids showed less change as compared with the triglyceride component. Tissue lipase activity increased in hearts perfused with or without glucose, but was unchanged relative to initial values with exogenous palmitate present. 4. 4. Direct evidence has been obtained for a regulatory role of exogenous-substrates on endogenous triglyceride fatty acid mobilization and oxidation in the working rat heart.
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Schedule a callMore From: Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism
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