Effects of maternal dietary L‐carnitine on fetal carnitine status as measured by tissue carnitine accumulation and kinetics of carnitine palmitoyltransferase in fetal pigs

To evaluate the effects of increasing maternal canitine on carnitine status and development of carnitine palmitoyltransferase (CPT) in the fetus, pregnant gilts were fed diets supplemented with 0 or 88 mg/d L‐carnitine (n=10/trt) during the first 70 d of gestation. Carnitine and CPT were analyzed in tissues collected from fetuses on d 70. Maternal carnitine supplementation increased fetal carnitine concentrations in liver and muscle tissues, but not in kidney tissue. Specifically, the concentrations of free carnitine were increased by 58% in liver and 33 % in muscle of fetuses from gilts fed carnitine compared to those from control gilts (P < 0.001). However, the increase in tissue carnitine concentration had no effect on CPT apparent kinetic constants (P > 0.1). Hepatic Vmax and Km for carnitine averaged 18.2 nmol/h.mg wet tissue and 0.53 mM, and were unaffected by maternal diet (P > 0.1). Notably, the concentrations of carnitine measured in liver tissues were only 25–40% of the Km‐values. Renal Vmax and Km values averaged 11.2 nmol/h.mg wet tissues and 0.31 mM, and likewise were not affected by treatment (P > 0.1). The Km and Vmax were not determined in muscle tissue because the highest CPT activity determined in muscle was less than 0.3 nmol/h.mg wet tissue. We conclude that carnitine ingestion during pregnancy increases carnitine concentrations in liver and muscle of the fetus, but does not impact CPT kinetics. Supported by Lonza, Inc.