Abstract des Autors

Little is known about the role of intramuscular triacylglycerol (IMTG) during exercise. Evidence was provided that IMTG is a substrate that can deliver energy during exercise and can contribute significantly to energy metabolism in certain conditions. The regulation of IMTG oxidation is mediated by a hormone sensitive lipase which is under control of the adrenergic nervous system. Adrenergic stimulation will increase intramuscular lipolysis while insulin is a strong inhibitor of this process. Endurance trained individuals have higher IMTG concentrations that their untrained counterparts and the oxidation rates of IMTG during exercise are also higher. Different fibre types have different capacities to oxidise IMTG, type I fibres having the largest capacity to store and to oxidise IMTG. Recent studies have suggested that IMTG is linked to insulin resistance in patients with non-insulin dependent diabetes mellitus (NIDDM). This seems to contradict the finding that trained individuals have increased IMTG stores and generally have an increased insulin sensitivity. Future research should elucidate the effect of IMTG and the role of its localisation on insulin resistance. Although there is evidence that IMTG play an important role in energy metabolism, future research is needed to determine the role and the regulation of this energy substrate. Present techniques to study IMTG metabolism have their limitations. Future research should focus on the role of hormone sensitive lipase, the interaction between IMTG and glucose transport and new techniques need to be developed to provide the tools needed to accurately quantify IMTG concentration and utilization. Verf.-Referat