Muscle acylcarnitines during short-term fasting in lean healthy men

Maarten R Soeters (1) , Hans P. Sauerwein , Marinus Duran , Ronald J. Wanders , Mariëtte T Ackermans , Eric Fliers , Sander M Houten , Mireille J Serlie

1 Endocrinology and Metabolism

The transition from the fed to the fasted resting state is characterized by, amongst others, changes in lipid metabolism and peripheral insulin resistance. Acylcarnitines have been suggested to play a role in insulin resistance besides other long-chain fatty acid metabolites. Plasma levels of long-chain acylcarnitines increase during fasting, but this is unknown for muscle long-chain acylcarnitines. We studied whether muscle long-chain acylcarnitines increase during fasting and their relation with glucose/fat oxidation and insulin sensitivity in lean healthy humans. After 14 and 62 hours of fasting, glucose fluxes, substrate oxidation, plasma and muscle acylcarnitines were measured before and during a hyperinsulinemic euglycemic clamp. Hyperinsulinemia decreased long-chain muscle acylcarnitines after 14 hours of fasting but not after 62 hours of fasting. In both the basal state and during the clamp glucose oxidation was lower and fatty acid oxidation was higher after 62 hours vs. 14 hours of fasting. Absolute changes in glucose and fat oxidation in the basal vs. hyperinsulinemic state were not different. Muscle long-chain acylcarnitines did not correlate with glucose oxidation, fatty acid oxidation or insulin-mediated peripheral glucose uptake. After 62 hours of fasting, the suppression of muscle long-chain acylcarnitines by insulin was attenuated compared to 14 hours of fasting. Muscle long-chain acylcarnitines do not unconditionally reflect fatty acid oxidation. The higher fatty acid oxidation during hyperinsulinemia after 62 vs. 14 hours of fasting although the absolute decrease in FAO was not different, suggests a different set point.

Mots clés: Medicine

Maarten R Soeters, Hans P. Sauerwein, Marinus Duran, Ronald J. Wanders, Mariëtte T Ackermans, et al.. Muscle acylcarnitines during short-term fasting in lean healthy men. Clinical Science, 2009, 116 (7), pp.585-592. ⟨10.1042/CS20080433⟩. ⟨hal-00479449⟩