An improved method for determination of serum and plasma triglycerides

A simple enzymatic fluorimetric method for the determination of triglycerides in 10 microliters of serum

An assay for the determination of triglyceride (acyl glycerol) in microliter volumes of serum or plasma is described. The method is based on enzymatic hydrolysis of triglyceride by lipase from Rhizopus arrhizus followed by enzymatic fluorimetric assay of the glycerol so released. Under the conditions of the assay the enzymatic hydrolysis is complete for concentrations up to 5 mmol/l in less than 15 min at room temperature. The determination of free glycerol and glycerol released is based on the formation of dihydroxyacetone in the presence of NAD and glycerol dehydrogenase. The NADH which is formed in stoichiometric quantities is estimated fluorimetrically. In the presence of the ketone-trapping agent hydrazine the reaction goes to completion above pH 9.0. By this method acyl glycerol can be measured routinely in a 10 microliters sample of serum or plasma. The test is extremely sensitive compared to previously described methods and exhibits acceptable precision and reproducibility.

Triacylglycerol contents and in vivo lipogenesis of ob/ob, db/db and Avy/a mice

The triacylglycerol content and the in vivo lipogenesis rates of the liver and the carcass of 12 groups of mice were studied. They were mice of three strains and affected by mutations at three loci: C57BL/6J-ob/ob and normal mice; C57BL/KsJ-db/db and normal mice; and VY/WfL-Avy/a and normal mice. Each type of mice was studied at two body weight levels, before and after the mutants became grossly obese. It was found that the C57BL/6J-ob/ob and the C57BL/KsJ-db/db mice had the characteristics of juvenile type obesity. They had higher lipogenesis rates and accumulated more triacylglycerol when they were young. They gained weight rapidly mainly due to the accumulation of more triacylglycerol as they matured. Their total triacylglycerol content could reach 50% of their body weight. At maturity, their lipogenesis rates had decreased to normal. In contrast, the VY/WfL-Avy/a mice had the characteristics of maturity-onset type obesity. When they were young, they did not have higher lipogenesis rates and had only a moderate amount of triacylglycerol stored. They did not gain weight rapidly as they matured. However, when they reached maturity, their lipogenesis rate did not decrease. Their body triacylglycerol content was about 25% of their weight.