Distribution of carnitine and acylcarnitine in the hamster epididymis and in epididymal spermatozoa during maturation

Abstract

The highest levels of carnitine and acylcarnitine were found in the cauda epididymis, and spermatozoa from the cauda contained greater amounts of total carnitine (free carnitine plus acylcarnitine) than those removed from the corpus or caput epididymis. Spermatozoa from the distal cauda contained significantly greater amounts of both free and total carnitine than those removed from the proximal cauda epididymis. The acylcarnitine:carnitine ratio was 1.7 and 0.37 in caput and cauda spermatozoa, respectively and 1.7 and 1.3 in caput and cauda fluid, respectively. It is suggested that the accumulation of carnitine is involved in sperm maturation and that acylcarnitine serves as an energy substrate for epididymal spermatozoa.