Effect of nutritional substrate on sulfolipids metabolic turnover in isolated renal tubules from rat

Effects of a glycolytic (glucose) and a gluconeogenic renal nutritional substrate (glutamine) on metabolic turnover of sulfolipids, determined as [S-35] sulfate incorporation, were compared in renal tubules prepared from well-fed rats. The results showed that the effects of glucose and glutamine, at nearly physiological serum concentration, are quite contrary to each other. Glucose increased the turnover rates of relatively long chain ganglio-series sulfoglycolipids (Gg(3)Cer II3-sulfate and Gg(4)Cer II3, IV-bis-sulfate) (1.7 to 2.4-fold), but not of cholesterol 3-sulfate (0.9-fold). In contrast, glutamine accelerated the turnover rates of relatively short chain sulfoglycolipids (glucosyl sulfatide, galactosyl sulfatide and lactosyl sulfatide) (1.3 to 2.7-fold), as well as cholesterol 3-sulfate (2.4-fold). The possible mechanism which causes these marked differences is also discussed.