Maternal Dietary l-Carnitine Supplementation Influences Fetal Carnitine Status and Stimulates Carnitine Palmitoyltransferase and Pyruvate Dehydrogenase Complex Activities in Swine

摘要

Effects of increasing maternal l-carnitine on carnitine status and energy metabolism in the fetus were evaluated by feeding pregnant swine a corn-soybean–based diet containing either 0 or 50 mg/kg added l-carnitine (n = 10/treatment) during the first 70 d of gestation. Carnitine, carnitine palmitoyltransferase (CPT), and pyruvate dehydrogenase complex (PDHC) activities were analyzed in tissues collected from fetuses on d 55 and 70. Maternal l-carnitine supplementation increased both fetal free and long-chain carnitine concentrations by 45% in liver and free carnitine by 31% in heart tissues but did not affect kidney tissue. Elevations in free and acylcarnitines increased with gestational age from 55 to 70 d in liver but not in heart and kidney. The increased carnitine concentrations resulted in a 45% increase in PDHC activity in heart and liver on d 70 of gestation but did not affect kidney and liver on d 55 of gestation. The increases in carnitine concentrations were accompanied by a 70% increase in hepatic CPT activity in 70-d-old fetuses, but activities in heart and kidney were unaffected. The Michaelis constant (Km) of CPT for carnitine in fetal tissues was not influenced by carnitine supplementation (P 0.1). Notably, the concentrations of carnitine measured on d 70 were only 25–40% of the Km values in liver, 60–70% in heart, and 30–40% in kidney (P 0.001). We conclude that carnitine ingestion during pregnancy increases fetal carnitine concentrations and stimulates heart PDHC and liver CPT activity without altering carnitine Km.