Abstract
The comparative incorporation of acetate into long chain fatty acids and acetyl carnitine by cell-free preparations of rat heart has been investigated. Whereas the addition of 1 mM carnitine stimulated (45%) fatty acid synthesis by liver preparations in citrate-containing media, fatty acid synthesis from acetate in rat heart homogenates under the same incubation conditions was markedly depressed. This depression by carnitine of acetate incorporation into long chain fatty acids in 105,000 × g soluble fractions of heart was associated with increased acetyl carnitine formation. Thus in heart tissue acetyl CoA is effectively shuttled into acetyl carnitine and is unavailable for synthesis of fatty acids. These data are in agreement with results obtained earlier in studies with perfused rat heart. A similar conversion of added acetyl CoA to the carntine derivative occurred when labeled malonyl CoA was used as fatty acid precursor, again resulting in reduced fatty acid synthesis. It was shown by direct measurement that acetyl carnitine formation in the absence of carnitine was greatest in heart mitochondria and least in microsomes. In the presence of carnitine, acetyl carnitine formation was increased in all subcellular fractions, with the greatest change again occurring with mitochondria.
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Vahouny, G.V., D'Amato, P.H. & Rodis, S.L. Acetyl carnitine formation in rat heart. Lipids 8, 446–452 (1973). https://doi.org/10.1007/BF02531762
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DOI: https://doi.org/10.1007/BF02531762