Muscle Triglycerides

Muscle tissue from the lateral vastus of the femoral muscle was taken by needle biopsy from 59 healthy fasting men 20–61 years of age and analysed for triglycerides, phospholipids and glycogen. The mean muscle triglyceride concentration increased with age and was 10.2 ± 0.9, 12.8 ± 1.6, 15.9 ± 1.0 and 16.2 ± 1.0 μmole/g for men in the third, fourth, fifth and sixth decades, respectively, while no consistent change was found in the mean concentration of phospholipids and glycogen. The concentration of phospholipids and glycogen was higher in subjects who reported “increased amounts of habitual physical activity” than in those reporting “normal” level. The muscle triglyceride concentration was apparently not influenced by the level of “physical activity”. The concentration of triglycerides in muscle was positively correlated to age and to the plasma triglyceride concentration. The correlation between the triglyceride concentration in muscle and plasma remained when the influence of age on these variables was eliminated by partial regression analysis. The possibility is discussed that the plasma triglycerides are of importance for the muscle triglyceride metabclism by supplying fatty acids for the triglyceride synthetizing system in the muscle tissue. No correlation was found between the concentration of triglycerides and glycogen in muscle. The standard deviation for differences in the triglyceride concentration between duplicate muscle samples was 2.4 μmole/g for subjects 20–39 years of age, 6.4 μtnole/g for subjects above 40 years of age. The corresponding values for the phospholipid concentration were similar in all age groups with a mean of 0.8 mg/g for all subjects.