Long-chain fatty acid uptake by skeletal myocytes: a confocal laser scanning microscopy study |
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Authors: | C Elsing J Górski C Boeker W Stremmel |
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Institution: | (1) Gastroenterology, Department of Medicine, University of Heidelberg, Bergheimerstr. 58, D-69115 Heidelberg (Germany), Fax +49 6221 564116, e-mail: christoph_elsing@krzmail.krz.uni-heidelberg.de, DE;(2) Department of Physiology, University Medical School of Bialystok, Bialystok (Poland), PL |
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Abstract: | Studies of regulation of free fatty acid (FFA) utilization by skeletal muscles have focused on plasma FFA delivery and on
intracellular factors affecting FFA metabolism. The present study was conducted to directly analyse the uptake process of
fatty acids into single myocytes. Cells were isolated from the rat flexor digitorum brevis muscle. Confocal laser scanning
microscopy was utilized to analyse the uptake of the fluorescent fatty acid derivative 12-NBD-stearate, which is not metabolized
by muscle tissue. Uptake represented a saturable function of the unbound fatty acid concentration in the medium (K
m 366 ± 118 nM, V
max 2.1 ± 0.3 AU/s) and depended on the medium sodium concentration. Reduced buffer pH increased initial uptake rates, whereas
lactate (10 mM) had no effect. Membrane hyper- and depolarization decreased uptake rates. This study demonstrates for the
first time kinetic data from isolated myocytes with evidence for a carrier-mediated transport mechanism for long-chain fatty
acids.
Received 31 March 1998; accepted 8 May 1998 |
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Keywords: | , Isolated myocytes, free fatty acid uptake, 12-NBD-stearate, confocal laser scanning microscopy, |
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