HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) [Supplemental Figures] All Versions of this Article: 79/2/253    most recent biolreprod.107.064659v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Lybaert, P. Articles by Lebrun, P. PubMed PubMed Citation Articles by Lybaert, P. Articles by Lebrun, P. Agricola Articles by Lybaert, P. Articles by Lebrun, P.

K_ATP Channel Subunits Are Expressed in the Epididymal Epithelium in Several Mammalian Species¹

Laboratories of Experimental Hormonology,³ Experimental Gastroenterology,⁴ and Pharmacology,⁵ Faculty of Medicine, Université Libre de Bruxelles (ULB), B-1070 Brussels, Belgium Institut de Pathologie et de Génétique,⁶ B-6280 Loverval, Belgium

ABSTRACT

Adenosine triphosphate-sensitive K⁺⁺ (K_ATP) channels are poorly characterized in the reproductive tract. The present study was designed to evaluate the putative expression of K_ATP channel subunits (Kir6.x and SURx) in the epididymis from different mammalian species. Immunohistochemical, Western blot, and RT-PCR techniques were used. A positive immunostaining for Kir6.2 (KCNJ11) and SUR2 (ABCC9) was observed by immunoenzymatic and immunofluorescent approaches in the principal epithelial cells throughout all regions of the rat and mouse epididymis. Double labeling with anti-aquaporin 9 (AQP9) and anti-Kir6.2 (KCNJ11) confirmed their colocalization in the principal cells. No immunostaining could be demonstrated for Kir6.1 (KCNJ8) and SUR1 (ABCC8) subunits. Under higher magnification, the immunostaining for Kir6.2 (KCNJ11) exhibited a cytoplasmic labeling that was more intense at the level of the Golgi apparatus along the whole epididymis. A similar pattern was observed for SUR2 (ABCC9), although in the latter case, the Golgi labeling appeared to be region specific. Spermatozoa in epididymal tubules from rodents also immunostained for Kir6.2 (KCNJ11) and SUR2 (ABCC9). Western blot analysis of epididymal total protein and crude membrane extracts from adult and prepubertal rats confirmed the presence of Kir6.2 (KCNJ11). SUR2 (ABCC9) protein expression was detected in adult epididymal extracts. Furthermore, RT-PCR established the presence of Kir6.2 (KCNJ11) and SUR2 (ABCC9) mRNA in prepubertal and adult mouse epididymis. Indirect immunofluorescence also documented the presence of Kir6.2 (KCNJ11) and SUR2 (ABCC9) in the epididymal epithelium, as well as in spermatozoa, of canine, feline, bovine, and human origin. These data demonstrate the presence of the K_ATP channel subunits, Kir6.2 (KCNJ11) and SUR2 (ABCC9), in epididymal epithelial cells and spermatozoa from several mammalian species. Although their physiological roles need to be fully characterized, it is tempting to propose that such types of K⁺⁺ channels might be involved in protein secretion and fluid-electrolyte transport occurring along the epididymal epithelium, leading to spermatozoa maturation.

epididymis, male reproductive tract, potassium channels, sperm maturation

¹Supported in part by the National Fund for Scientific Research (Belgium). P. Lebrun is a Research Director at the National Fund for Scientific Research.

Correspondence: ²Pascale Lybaert, Laboratory of Experimental Hormonology, Faculty of Medicine, Université Libre de Bruxelles (ULB), Route de Lennik 808, CP626, B-1070 Brussels, Belgium. FAX: 32 2 555 63 56; e-mail: plybaert{at}ulb.ac.be