Na+ reabsorption in cultured rat epididymal epithelium via the Na+/nucleoside cotransporter

G. P H Leung, K. H. Cheung, Chung Ming Tse, P. Y D Wong

Research output: Contribution to journalArticle

Abstract

The effect of nucleoside on Na+ reabsorption via Na+/nucleoside cotransporter in cultured rat epididymal epithelia was studied by short-circuit current (Isc) technique. Guanosine added apically stimulated Isc in a dose-dependent manner, with a median effective concentration (EC50) of 7 ± 2 μM (mean ± SEM). Removal of Na+ from the apical bathing solution or pretreatment with a nonspecific Na+/nucleoside cotransporter inhibitor, phloridzin, completely blocked the Isc response to guanosine. Moreover, the guanosine response was abolished by pretreatment of the tissue with ouabain, a Na+/K+-ATPase inhibitor, suggesting the involvement of Na+/nucleoside cotransporter on the apical side and Na+/K+-ATPase on the basolateral side in Na+ reabsorption. In contrast, the Isc response to guanosine was not affected after desensitization of purinoceptors by ATP. Addition of the Na+/K+/2Cl- symport inhibitor bumetanide to the basolateral side or the nonspecific Cl- channel blocker diphenylamine-2-carboxylate to the apical side showed no effect on the Isc response to guanosine, excluding stimulation of Cl- secretion by guanosine as the cause of the guanosine-induced Isc. The Isc response to purine nucleoside (guanosine and inosine) was much higher than that to pyrimidine nucleoside (thymidine and cytidine). Consistent with substrate specificity, results of reverse transcription-polymerase chain reaction revealed mRNA for concentrative nucleoside transporter (CNT2), which is a purine nucleoside-selective Na+/nucleoside cotransporter in the epididymis, but not for CNT1. It is suggested that the Na+/nucleoside cotransporter (i.e., CNT2) may be one of the elements involved in Na+ and fluid reabsorption in the epididymis, thereby providing an optimal microenvironment for the maturation and storage of spermatozoa.

Original languageEnglish (US)
Pages (from-to)764-769
Number of pages6
JournalBiology of Reproduction
Volume64
Issue number3
StatePublished - 2001
Externally publishedYes

Fingerprint

Guanosine
Epithelium
Purine Nucleosides
Epididymis
Nucleoside Transport Proteins
Pyrimidine Nucleosides
Sperm Maturation
Phlorhizin
Bumetanide
Purinergic Receptors
Cytidine
Inosine
sodium-nucleoside cotransporter
Ion Transport
Ouabain
Substrate Specificity
Nucleosides
Thymidine
Reverse Transcription
Adenosine Triphosphate

Keywords

  • Epididymis

ASJC Scopus subject areas

  • Cell Biology
  • Developmental Biology
  • Embryology

Cite this

Na+ reabsorption in cultured rat epididymal epithelium via the Na+/nucleoside cotransporter. / Leung, G. P H; Cheung, K. H.; Tse, Chung Ming; Wong, P. Y D.

In: Biology of Reproduction, Vol. 64, No. 3, 2001, p. 764-769.

Research output: Contribution to journalArticle

Leung, G. P H ; Cheung, K. H. ; Tse, Chung Ming ; Wong, P. Y D. / Na+ reabsorption in cultured rat epididymal epithelium via the Na+/nucleoside cotransporter. In: Biology of Reproduction. 2001 ; Vol. 64, No. 3. pp. 764-769.
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