Adipocyte metabolism in endogenous hypertriglyceridemia

Abstract

In order to define specific metabolic abnormalities of adipose tissue metabolism in endogenous hypertriglyceridemia (EH) patients with this condition were compared with normolipidemic controls matched for body fat and fat cell size. In vitro the enlarged fat cells of EH were found to have an increased basal and noradrenaline-stimulated lipolysis in comparison with cells of the same size from normolipidemic controls. The insulin inhibition of noradrenaline-stimulated lipolysis was blunted. Lipoprotein lipase activity in these cells was clearly depressed. Basal triglyceride synthesis from labeled glucose was low in relation to plasma insulin. The reduction of insulin tolerance in vivo suggested that the depression of plasma glycerol and free fatty acid concentration was small in EH, suggesting that the more detailed findings in vitro were of relevance for in vivo conditions. It was suggested that the hyperinsulinemia and decreased glucose tolerance of EH may well be responsible for some of the aberrations of adipocyte metabolism in EH. The decreased responsiveness of lipolysis to insulin and the low lipoprotein lipase activity are, however, findings not typical for enlarged fat cells exposed chronically to insulin and might be characteristic for the fat cells of EH. It seems of importance to further define the factor(s) responsible for these metabolic aberrations, because the abnormalities of the acipocyte metabolism in EH may well offer a possible explanation to the pathogenesis of that condition.