Inwardly Rectifying K+ Channels in Spermatogenic Cells: Functional Expression and Implication in Sperm Capacitation

Developmental Biology

Ricardo Felix¹  José L. De la Vega-Beltrán¹  Alberto Darszon¹  Carlos Muñoz-Garay¹  Pedro Labarca¹  Ricardo Delgado¹ 

[1] Departamento de Genética y Fisiologı́a Molecular, Instituto de Biotecnologı́a, UNAM, Cuernavaca, México

关键词: K+ channel;    inward-rectifier;    spermatogenic cells;    sperm capacitation;    sperm acrosome reaction;   

DOI  :  10.1006/dbio.2001.0196

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Tofertilize,mammalianspermmustcompleteamaturationalprocesscalledcapacitation.Itisthoughtthatthemembranepotentialofspermhyperpolarizesduringcapacitation,possiblyduetotheopeningofK+channels,butelectrophysiologicalevidenceislacking.Inthisreport,usingpatch-clamprecordingsobtainedfromisolatedmousespermatogeniccellswedocumentthepresenceofanovelK+-selectiveinwardlyrectifyingcurrent.MacroscopiccurrentactivatedatmembranepotentialsbelowtheequilibriumpotentialforK+anditsmagnitudewasdependentontheexternalK+concentration.ThechannelsselectedK+overothermonovalentcations.CurrentwasvirtuallyabsentwhenexternalK+wasreplacedwithNa+orN-methyl-D-glucamine.AdditionofCs+orBa2+(IC50of∼15μM)totheexternalsolutioneffectivelyblockedK+current.DialyzingthecellswithaMg2+-freesolutiondidnotaffectchannelactivity.Cytosolicacidificationreversiblyinhibitedthecurrent.Weverifiedthattherestingmembranepotentialofmousespermchangedfrom−52±6to−66±9mVduringcapacitationinvitro.Notably,applicationof0.3–1mMBa2+duringcapacitationpreventedthishyperpolarizationanddecreasedthesubsequentexocytoticresponsetozonapellucida.AmechanismisproposedwherebyopeningofinwardlyrectifyingK+channelsmayproducehyperpolarizationunderphysiologicalconditionsandcontributetothecellularchangesthatgiverisetothecapacitatedstateinmaturesperm.

【 授权许可】

Unknown