Simple equations that relate glucose and glutamate 13 C-NMR multiplet areas to gluconeogenesis and pyruvate recycling during metabolism of |l,2,3-13 C3lpropionate are presented. In isolated rat livers, gluconeogenic flux was 1.2 times TCA cycle flux and about 40% of the oxaloacetate pool underwent recycling to pyruvate prior to formation of glucose. The 13 C spectra of glucose collected from rats after gastric versus intravenous administration of [l,2,3-13 C 3 ]propionate indicated that pyruvate recycling was slightly higher in vivo (49%) while glucose production was unchanged. This indicates that a direct measure of gluconeogenesis and pyruvate recycling may be obtained from a single 13 C-NMR spectrum of blood collected after oral administration of enriched propionate.
Summary. The content and composition of plasma and erythrocyte lipids from individuals having sickle cell anaemia has been determined. The plasma contains a significantly reduced content of both cholesterol and phospholipid while the ratio of cholesteryl ester to total cholesterol, the distribution of phospholipids classes, triglyceride concentration and the fatty acid content were similar to normal values. However, the free glycerol content of the plasma was eight‐fold higher than normal. Erythrocyte lipids contain an elevated level of cholesterol and control levels of phospholipid content, phospholipid distribution and fatty acid content. The plasma was separated by ultracentrifugation into VLDL (density <1.006), LDL (1.006< d <1.063) and HDL (1.063< d< 1.21). Significant decreases in cholesterol and phospholipid were observed in LDL and HDL.
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