Glycerol phosphorylation and oxidation in pancreatic islets.

Homogenates of rat pancreatic islets and tumoral islet cells (RINm5F line) were found to display glycerokinase activity. In the islets like in the liver, about one-sixth of the enzyme appears bound to mitochondria. The enzymatic activities in liver and islets differ from one another, however, by their response to increasing concentrations of either glycerol or ATP and sensitivity to inhibition by D-glyceraldehyde. In intact islets, [U-14C]glycerol is efficiently oxidized, albeit at a much lower rate than that found for its phosphorylation by islet homogenates. These findings are relevant to the role played by glycerol liberated from endogenous triglycerides in the basal respiration of islet cells.