1. Contemporary stable isotope methodology was applied in combination with muscle biopsy sampling to accurately quantify substrate utilisation and study the regulation of muscle fuel selection during exercise. 2. Eight cyclists were studied at rest and during three consecutive 30 min stages of exercise at intensities of 40, 55 and 75 % maximal workload (W(max)). A continuous infusion of [U-(13)...

Mechanistic details of mammalian metabolism in vivo and dynamic metabolic changes in intact organisms are difficult to monitor because of the lack of spatial, chemical, or temporal resolution when applying traditional analytical tools. These limitations can be addressed by sensitivity enhancement technology for fast in vivo NMR assays of enzymatic fluxes in tissues of interest. We apply this me...

The composition of fourteen infant formulae and six follow-up milks with regard to their free amino acids (including taurine), free nucleotides, orotic acid, and free and total l-carnitine content was studied. The levels found were compared with the limits established in European legislation and with the composition of human and cows' milk samples. HPLC methodologies, optimized and validated fo...

The effects of carnitine were evaluated in diets fed to hybrid striped bass. The basal diet contained 34.6% crude protein supplied by casein, gelatin and crystalline L-amino acids and 6.0% lipid supplied by menhaden oil. Four dietary treatments contained L-carnitine concentrations of either 2.1, 41.0, 212.0 or 369.7 mgrkg diet. Dietary treatments were fed to apparent satiation twice daily to tr...

INTRODUCTION Carnitine is an essential cofactor in mitochondrial fatty acid oxidation. Carnitine deficiency results in accumulation of non-oxidized fatty acyl-coenzyme A molecules, and this inhibits intra-mitochondrial degradation of ammonia. Hyperammonemia may lead to encephalopathy. This scenario has been previously reported. CASE PRESENTATION We report the case of a 47-year-old Caucasian m...

Carnitine deficiency related to epilepsy or antagonism of carnitine by antiepileptic drugs (AEDs) has attracted increasing attention since the first recognition of a neuromuscular deficiency syndrome in 1973’. Carnitine deficiency is linked to the potentially fatal hepatotoxicity that occasionally attends valproate therapy, particularly in children2, and has been documented in adult and pediatr...

We investigated the influence on mitochondrial functions in carnitine deficiency caused by short-term treatment of cefteram-pivoxil (CFTM-PI) which is one of pivaloyloxymethyl-esterified antibiotics in adult volunteers and diseased children. Administration of CFTM-PI caused hypocarnitinemia in all cases, and we observed a significant elevation of blood ammonia levels compared with those after i...

Hamsters with either the dilated (BIO 53.58) or hypertrophic (BIO 14.6) form of cardiomyopathy and an inbred control strain of hamster (F1B) were treated for 6 months with high-dose L-carnitine (1 g/kg/day i.p.). After treatment, the animals were killed and their hearts perfused by the isolated working technique. Mechanical performance (as indicated by the double product of heart rate and left ...

The present study was conducted to examine the effects of L-carnitine on pulmonary hypertensive response in broiler chickens reared at high altitude and exposed to hypobaric hypoxia. A total of 192 day-old male broilers (Cobb 500) were randomly assigned to 4 treatments and 4 replicates of 12 chicks. A basal diet composed of mainly corn and soybean meal was formulated and served as a control. Th...

Long chain fatty acids are oxidized by rat liver mitochondria provided that endogenous adenosine triphosphate is not depleted. If endogenous ATP is depleted, e.g. by Z,&dinitrophenol, external ATP as well as carnitine is required for fatty acid oxidation. Atractyloside does not block this reaction in media containing orthophosphate buffer. Oligomycin can substitute for carnitine, but the oligom...