CRR. Unit for the Study of Mitochondrial Physiology3 and

Experiments were performed to further elucidate the role of -amino--hydroxybutyric acid tritnethylbetaine (carnitine) on the metabolism and functions of spermatozoa. Addition of 20 mM L-carnitine to suspensions of ejaculated bovine spermatozoa resulted in an increase of cellular cakiwn transport, whereas 20mM L-aminocar-nitine (an inhibitor of carnitinepalmitoyltransferase) caused an inhibition of this process. Both L-carnitine and L-aminocarnitine inhibited the progressive motility of spermatozoa, and the oxygen consumption as well as the release of the enzymes hyaluronidase and glutamate-oxaloacetate transaminase from spermatozoa. Labeled car-nitine was rapidly taken up by spermatozoa by a process strongly dependent on temperature and extracellular concentration of carnitine. It is concluded that the effects produced by high concentrations of carnitine or aminocarnitine are mainly due to interactions ofthese compounds with the cellular membranes of spermatozoa