PIVALIC ACID-INDUCED CARNITINE DEFICIENCY AND PHYSICAL EXERCISE IN HUMANS

To study the effect of carnitine depletion on physical working capacit y, healthy subjects were administered pivaloyl-conjugated antibiotics for 54 days. The mean carnitine concentration in serum decreased from 35.0 to 3.5 mu mol/L, and in muscle from 10 to 4.3 mu mol/g noncollage n protein (NCP). Exercise tests were performed before and after 54 day s' administration of the drug. At submaximal exercise, there was a sli ght increase in the concentration of 3-hydroxybutyrate in serum, presu mably caused by decreased fatty acid oxidation in the liver. There was also a decreased consumption of muscle glycogen, indicating decreased glycolysis in the skeletal muscle. The muscle presumably had enough e nergy available, since there was no significant decrease in the concen tration of adenosine triphosphate (ATP) and creatine phosphate during exercise. The work at maximal oxygen uptake (Vo(2)max) and the maximal heart rate were reduced. Since Vo(2)max is considered dependent on he art function, carnitine depletion seemed to affect cardiac function. C opyright (C) 1996 by W.B. Saunders Company