Carnitine status, plasma lipid profiles, and exercise capacity of dialysis patients: Effects of a submaximal exercise program

Abstract Carnitine status, blood lipid profiles, and exercise capacity were evaluated in a combined group of hemodialysis (N = 4) and continuous ambulatory peritoneal dialysis (N = 6) patients before and after an 8-week submaximal exercise program. Maximal aerobic capacity (VO 2 max) was only 18.5 ± 5.9 (mean ± SD) mL O 2 /kg/min, well below the expected 30 to 35 mL O 2 /kg/min for age-matched sedentary controls. Plasma short-chain acylated carnitine levels, which were two to three times normal values, were reduced after the exercise program, but the long-chain acylcarnitines were significantly reduced during acute exercise. Muscle biopsies of the vastus lateralis were performed at rest in five patients prior to and after the 8-week exercise program. Total carnitine in skeletal muscle was 3.09(0.76 SD) μmol/g ww, with only 11.3% acylated prior to the exercise program, which was much lower than the 4.25 ± 1.27 μmol/g ww, with 28.5% acylated in a group of healthy athletic subjects (N = 28). Muscle free carnitine concentrations decreased significantly following the 8-week training period, with only a slight reduction in total carnitine. The percent of acylated carnitine was therefore significantly increased ( P v 1.80 ± 0.51 nmol /5 min/ >mg protein in 28 healthy normals ( P