Our study investigated the potential for important in vivo drug-nutrient transport interactions at the lactating mammary gland using the L-carnitine transporter substrates, cefepime and L-carnitine, as proof-of-concept. On d 4 (n = 6/treatment) and d 10 (n = 6/treatment) of lactation, rats were administered cefepime (250 mg/h) or saline by continuous i.v. infusion (4 h). Serum and milk L-carnit...

We studied the effect of intravenously infused carnitine (34 mumol.100 g-1.d-1) on protein and branched-chain amino acid (BCAA) metabolism in rats either starved for 3 d or parenterally fed for 7 d. Carnitine infusion did not significantly affect nitrogen balance, protein content of liver and muscle, plasma concentrations of BCAA and branched-chain keto acid, or leucine oxidation and incorporat...

The rapid association of Na-[16-(14)C]palmitate with isolated rat liver mitochondria was measured by an oil separation method. This association was time and temperature-dependent and was absolutely dependent on the presence of exogenous ATP and CoASH and partially dependent on exogenous carnitine. Carnitine dependence was enhanced at lower concentrations of [(14)C]palmitate. At 6.5 micro M [(14...

A total of 64 neonatal pigs was used in an experiment to study the effect of L-carnitine and soybean oil on pig performance and N and energy utilization. Pigs were weaned at an average of 3 d of age and individually fed diets that contained dextrose, corn syrup solids, and isolated soy protein for 21 d. Two levels of soybean oil (1.18 or 12.31%) and L-carnitine (0 or 800 ppm) were used in a fac...

Serum concentrations of total carnitine, free carnitine and acylcarnitine were measured in forty-one epileptic patients treated with valproic acid (VPA). Among them, 14 patients were on VPA monotherapy and 27 were on VPA polytherapy. Forty-one age and sex matched healthy normal controls were also evaluated for carnitine metabolism. The mean total and free carnitine were significantly lower in b...

In an accompanying publication, we have shown that in most tissues there is an approximate correspondence between levels of carnitine acetyltransferase activity and concentrations of carnitine or acetylcarnitine (1). In addition, this correspondence may generally be related to the magnitude of the increase in fatty acid oxidation elicited by added carnitine in particular tissue preparations (1,...

BACKGROUND Ninety-five percent of the body carnitine pool resides in skeletal muscle where it plays a vital role in fuel metabolism. However, vegetarians obtain negligible amounts of carnitine from their diet. OBJECTIVE We tested the hypothesis that muscle carnitine uptake is elevated in vegetarians compared with that in nonvegetarians to maintain a normal tissue carnitine content. DESIGN F...

To determine whether accumulation of long-chain acyl carnitine contributes to electrophysiological abnormalities induced by hypoxia, we characterized effects of normoxic and hypoxic perfusion on the subcellular distribution of endogenous long-chain acyl carnitine and transmembrane potentials of cultured rat neonatal myocytes. Hypoxia increased long-chain acyl carnitine more than 5-fold. Sodium ...

Previous findings in rats and in human vegetarians suggest that the plasma carnitine concentration and/or carnitine ingestion may influence the renal reabsorption of carnitine. We tested this hypothesis in rats with secondary carnitine deficiency following treatment with N-trimethyl-hydrazine-3-propionate (THP) for 2 weeks and rats treated with excess L-carnitine for 2 weeks. Compared to untrea...