Studies on Carnitine Synthesis in the Rat Epididymis

Department of Reproductive Physiology, Oregon Regional Primate Research Center, 505 N.W. 185th Avenue, Beaverton, Oregon 97005, U.S.A. (Received 9th December 1974) Carnitine is present in high concentrations in the epididymides of rats (Marquis & Fritz, 1965) and other species (Casillas, 1972). Since bull spermatozoa accumulate carnitine as they pass through the epididymis (Casillas, 1973), this organ appears to supply carnitine to spermatozoa as they mature. The metabolic role of carnitine in mature spermatozoa has been studied (Casillas, 1972; Casillas & Erickson, 1975), but little is known about how it accumulates in epididymal fluids and in spermatozoa. Here, we report the results of in-vitro experiments designed to test whether the epididymis has the ability to convert 4-N-trimethylaminobutyrate, the immediate precursor, to carnitine. Rats (strain CD) of known birth date were obtained from the Charles River Breeding Laboratories, Wilmington, Massachusetts, and were maintained on a diet of laboratory chow and water. Epididymal