ABSTRACT
Introduction Carnitine, essentially meaning “flesh” in Latin, was simultaneously discovered in meat extracts by the Russian scientists Gulewitsch and Krimberg and the German researcher Kutscher in the early part of the twentieth century [1, 2]. Around twenty years passed before carnitine was classified as 3-hydroxy-4-N,N,N-trimethylaminobutyric acid, a watersoluble quaternary amine [3]. Midway through the twentieth century interest in carnitine’s role in biology grew following its identification as vitamin Bt, an essential growth factor in Tenebrio molitor beetle larvae [4]. Shortly thereafter, carnitine’s role in energy metabolism began to be elucidated when German researchers showed that pigeon liver homogenates could exchange acyl groups between carnitine and acyl-coenzyme A (CoA) [5]. In the same year Irving B. Fritz demonstrated that the addition of a skeletal muscle homogenate to rat liver sections elevated palmitate oxidation, where Fritz concluded that carnitine was the ingredient within the muscle homogenate responsible for this finding [6]. In the ensuing decades, pioneering work by Fritz, among others, elucidated carnitine’s
Introduction ...................................................................................................... 37 The role of carnitine in long-chain fatty acid oxidation ............................. 38 The role of carnitine as an acetyl group buffer ............................................ 42 Carnitine as a regulator of skeletal muscle fuel selection .......................... 44 Summary remarks ............................................................................................ 46 References .......................................................................................................... 47
metabolic role in lipid metabolism. These researchers concluded that only long-chain acylcarnitine and not long-chain acyl-CoA could permeate the mitochondrial membranes in a variety of mammalian tissues; as such, carnitine, the principal substrate for the carnitine palmitoyl system, played an obligatory role in long-chain fatty acid oxidation [7-10].
