Abstract
To study on plasma lipid metabolism in lipoatrophic diabetes, the turnover rate of plasma free fatty acid (FFA) and triglyceride (TG) was measured in two cases of the congenital type of lipoatrophic diabetes using, 14C-palmitic acid as a tracer.
After an overnight fast, 5 μCi of 14C-palmitic acid was injected intravenously in 30 seconds into two patients. Venous blood samples were drawn at appropriate intervals during the 32 hours after administration of 14C-fatty acid. The total lipids were extracted from one-ml aliquots of plasma by the method of Dole, and FFA and TG in the extract were separated according to the modified method of Borgström. Radioactivity of each sample was measured in a gas-flow counter.
The half periods of decay (T 1/2) of plasma 14C-palmitic acid were 4.5 and 7.5 minutes, which are longer than the values of 1.4-3.4 minutes for the normal subjects reported by Fredrickson. This result indicates that lypolysis is decreased in these cases, and so enhanced lypolysis is not the cause of lipoatrophy in this disorder.
Radioactivity in plasma TG fractions reached the maximum 2 hours after the injection of 14C-palmitic acid. The fractional disappearance rates af plasma TG were 0.107 and 0.074 rate/hour, which were relatively lower than the values of 0.078-0.347 rate/hour reported by Friedberg for normal subjects.
