Relationship of carnitine transport across the epididymis to blood carnitine and androgens in rats.

The aim of this study was to establish whether a rise in plasma carnitine and testosterone stimulates carnitine uptake in the epididymis. Three groups of rats were injected SC with testosterone enanthate (2.35, 2.40, and 3 mg/kg body weight, respectively, three times a week for 4 weeks) and compared to controls. All three doses proved effective and induced a rise in the weight of the seminal vesicles and prostate, thus reflecting a rise in plasma androgen levels. Testosterone enanthate reduced both testicular weight and the number of spermatozoa in the testes. It raised the level of blood carnitine by 40% in group 1 and by 150% in groups 2 and 3, but the carnitine concentration in the epididymal fluid did not change. These results suggest that the system of carnitine transport across the epididymis is saturated, and that it is not activated by a rise in plasma testosterone.