Transport of carnitine and acetylcarnitine by carnitine/organic cation transporter (OCTN) 2 and OCTN3 into epididymal spermatozoa.

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Kobayashi D, Tamai I, Sai Y, Yoshida K, Wakayama T, Kido Y, Nezu J, Iseki S, Tsuji A

Transport of carnitine and acetylcarnitine by carnitine/organic cation transporter (OCTN) 2 and OCTN3 into epididymal spermatozoa.

Reproduction. 2007 Nov;134(5):651-8.

PubMed ID

17965255 [ View in PubMed

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Abstract

Carnitine and acetylcarnitine are important for the acquisition of motility and maturation of spermatozoa in the epididymis. In this study, we examined the involvement of carnitine/organic cation transporter (OCTN) in carnitine and acetylcarnitine transport in epididymal spermatozoa of mice. Uptake of both compounds by epididymal spermatozoa was time-dependent and partially Na(+)-dependent. Kinetic analyses revealed the presence of a high-affinity transport system in the spermatozoa, with K(m) values of 23.6 and 6.57 muM for carnitine and acetylcarnitine respectively in the presence of Na(+). Expression of OCTN2 and OCTN3 in epididymal spermatozoa was confirmed by immunofluorescence analysis. The involvement of these two transporters in carnitine and acetylcarnitine transport was supported by a selective inhibition study. We conclude that both Na(+)-dependent and -independent carnitine transporters, OCTN2 and OCTN3, mediate the supply of carnitine and acetylcarnitine to epididymal spermatozoa in mice.

DrugBank Data that Cites this Article

Drug Transporters

Drug	Transporter	Kind	Organism	Pharmacological Action	Actions
Acetylcarnitine	Solute carrier family 22 member 21	Protein	Mouse	Unknown	Substrate	Details
Acetylcarnitine	Solute carrier family 22 member 5	Protein	Humans	Unknown	Not Available	Details