Maternal and Fetal Tissue Distribution of L-Carnitine in Pregnant Mice: Low Accumulation in the Brain

The distribution of L-carnitine was studied by whole-body au-toradiography in pregnant CD-I mice at 1, 2, 3, and 6 hr after receiving L-[l4C]carnitine. Highest concentrations of carnitine were found in maternal tissues including liver, placenta, kidney, myocardium, and choroid plexus. High retention of tissue car-nitine in excess of blood levels suggests the existence ofconcen-trative uptake mechanism. Labeled carnitine was not detectable in either maternal or fetal brain. This suggests that the brain barrier systems limit the access of L-carnitine to the brain. In fetus, the level of carnitine was less than that seen in the maternal tissues, however, the tissue distribution was similar. The fetal tissue carnitine concentration increased with time. These findings suggest that relief of encephalopathy due to toxic organic anions in metabolic disorders following L-carnitine supplementation appears to be peripheral metabolic effects rather than direct ac