title: Functional expression of a Ca2+-activated K+ channel in Xenopus oocytes injected with RNAs from the rat testis.
abstract: The present study investigated the feasibility of using Xenopus oocytes to express sperm ion channel by injection of RNAs extracted from the rat testis. The RNA-injected oocytes expressed an outwardly rectifying current which was dependent on K+ concentration and inhibitable by K+ channel blockers, charybdotoxin (CTX) and tetraethylammonium (TEA). The Ca2+ ionophore, ionomycin, could also stimulate current activation with similar current characteristics in the RNA-injected oocytes, suggesting the expression of a Ca2+-activated K+ channel. Immunolocalization indicated predominant Ca2+-activated K+ channel immunoreactivity associated with spermatogenic cells. Reverse transcriptase-polymerase chain reaction studies confirmed the expression of the Ca2+-activated K+ channel mRNA in isolated spermatogenic cells. Our results suggest that ion channels and/or receptors of spermatogenic cells could be investigated using the Xenopus oocyte as an expression system. The present study also suggests that sperm may possess a Ca2+-activated K+ channel which has been implicated in the process of sperm activation and gamete interaction.
authors.affiliation: Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: W L
authors.initials: WL
authors.lastname: Wu
authors.forename: S C
authors.initials: SC
authors.lastname: So
authors.forename: Y P
authors.initials: YP
authors.lastname: Sun
authors.forename: T S
authors.initials: TS
authors.lastname: Zhou
authors.forename: Y
authors.initials: Y
authors.lastname: Yu
authors.forename: Y W
authors.initials: YW
authors.lastname: Chung
authors.forename: X F
authors.initials: XF
authors.lastname: Wang
authors.forename: Y D
authors.initials: YD
authors.lastname: Bao
authors.forename: Y C
authors.initials: YC
authors.lastname: Yan
authors.forename: H C
authors.initials: HC
authors.lastname: Chan
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D018999:Charybdotoxin / Q000494:pharmacology; D004594:Electrophysiology; D015870:Gene Expression / Q000235:genetics; D007150:Immunohistochemistry; D015759:Ionomycin / Q000494:pharmacology; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008297:Male; D008845:Microinjections; D009865:Oocytes / Q000378:metabolism*; D010446:Peptide Fragments / Q000276:immunology; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D013094:Spermatozoa / Q000378:metabolism; D013737:Testis / Q000737:chemistry*; D019789:Tetraethylammonium / Q000494:pharmacology; D014981:Xenopus
chemical_list: D051036:Large-Conductance Calcium-Activated Potassium Channels; D010446:Peptide Fragments; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D012333:RNA, Messenger; D018999:Charybdotoxin; D015759:Ionomycin; D019789:Tetraethylammonium; D002118:Calcium