Experimental carnitine depletion in rats.

We studied tissue carnitine concentrations after long-term peroral feeding with carnitine-free parenteral nutrient solutions in rats. Group I (n = 22) was fed perorally for 6 weeks with the carnitine free experimental diet. The control group (group II, n = 22) was pair-fed a standard laboratory pellet diet containing carnitine 60 nmol/g. The carnitine free experimental diet caused approximately 50% depletion of carnitine in serum, muscle, and liver while the concentrations in the pair-fed rats were normal. The free and total carnitine concentrations in serum were 25.5 +/- 7.8 and 32.9 +/- 9.3 micromol/l (group I), and 69.3 +/- 13.7 and 84.1 +/- 16.5 micromol/l (group II, p < 0.001), in muscle 2.1 +/- 0.3 and 2.3 +/- 0.4 micromol/g dry weight (group I), and 3.8 +/- 0.6 and 4.3 +/- 0.8 micromol/g dry weight (group II, p < 0.001), and in liver 0.5 +/- 0.1 and 0.6 +/- 0.1 micromol/g dry weight (group I), and 1.2 +/- 0.1 and 1.3 +/- 0.1 micromol/g dry weight (group II p < 0.001). Daily supplementation of the experimental liquid diet with I-carnitine caused normal tissue carnitine concentrations, indicating the exclusion of dietary carnitine as the cause of carnitine depletion. We conclude that in rats carnitine depletion in serum, muscle, and liver can be induced by prolonged peroral feeding with carnitine free diet.