Concentration of carnitine in human muscle tissue

Abstract

The concentration of acid-soluble carnitine has been determined in human muscle tissue and in plasma. One group of subjects consisted of patients mainly suffering from cholecystolithiasis or varicose veins. Biopsies were surgically obtained under general anesthesia. The other group consisted of normal subjects in which the biopsies were obtained by a percutaneous technique. We could not demonstrate a significant change in concentration of carnitine along a muscle fiber bundle or a difference in the concentration between specimens from superficial and deep levels. The rectus abdominis muscle had a lower carnitine concentration than the muscles of the leg. The median values were 13.7 μmoles/g dry weight (range 7.7–32.5) and 17.9 μmoles/g dry weight (range 6.5–24.1), respectively. Men had slightly higher concentrations in the rectus adbominis muscle than women. Median values were 15.4 μmoles/g dry weight (range 7.7–32.5) and 12.9 μmoles/g dry weight (range 9.8–17.7), respectively. Two subjects from whom biopsies were obtained with an interval of 91 and 42 days showed nearly the same values on both occasions. No correlation was found between age and carnitine concentration in muscle tissue. The carnitine concentration in two biopsies of human heart muscle was 4.2 μmoles/g dry weight and 4.8 μmoles/g dry weight, respectively. The median value of plasma carnitine concentration was 46.2 μmoles/1 (range 17.9–74.7). The concentration of carnitine in plasma was not correlated with the concentration of carnitine in muscle tissue.