碳酸氢盐在小鼠精子体外获能和顶体反应中的作用

检验了精子获能和透明带（ＺＰ）及孕酮激发顶体反应是否需要ＨＣＯ３／ＣＯ２。小鼠精子分别在改良的Ｔｙｒｏｄｅ（ｍＴ－Ｂ２５，含２５ｍｍｏｌ／ＬＨＣＯ３／ＣＯ２）或ｍＴ－Ｈ（无ＨＣＯ３Ｈ／ＣＯ２，含２０ｍｍｏｌ／ＬＨｅｐｅｓ）中预培养９０ｍｉｎ后，以２步７０％和３５％ｐｅｒｃｏｌｌ／ｍＴ－Ｈ洗涤精子，并将精子重新悬浮于ｍＴ－Ｂ２５，ｍＴ－Ｂ１５ｍＴ－ＢＨ和ｍＴ－Ｈ中，用ＩＺＰ／μｌ或１５μｍｏｌ／Ｌ孕酮激发精子顶体反应。在上述ｍＴ诸培养基中，“Ｂ”精子（以ＣＴＣ荧光染色法确定）发生率为６１％～６７％；顶体反应均可达到４１．０士１．４％～４８．０±１．４％。表示精子一旦在ＨＣＯ３／Ｃ０２环境中获能，顶体反应就可在无ＨＣＯ３／ＣＯ２环境中发生。然而，精子预先在ｍＴ－Ｈ中培养，与上述相同方法处理精子，“Ｂ”型精子（２２％～３３％）明显低于前者，对ＺＰ或孕酮的刺激不起反应（１４．Ｏ士３．６～２４．７士０．６％），甚至将精子重新悬浮于ｍＴ－Ｂ２５中也不发生反应（２２．０±９．５％），表示这些精子并未获能。上述结果表明小鼠精子获能依赖于ＨＣＯ３／ＣＯ２，但顶体反应则否。

BicarbOnate is essential for the acquisition of capacitation hut not for the acrosome reactiOn in mouse spermatozoa

bjectives:to investigate whether bicarbonate /CO2 are required for capacitation or for acrosome re-action(AR),triggered with zona pellucida(ZP)or progesterone(P).Design :In vitro experiments with mouse spermatozoa. setting :Research Laboratory of Babraham Institute,Cambridge. Methods :Mouse spermatozoa were incubated in mod ified Tyrode's medium( mT)with bicarbonate(mT-B25) and equilibrated in 5%CO2/air for 90 min and then washed through a 2-step percoll gradient(35%and 70%)in medium without bicarbonate but with Hepes (mT-H), resuspended in mT-B25, mT-B15, mT-BH and mT-Hand were then challenged with 1 ZP/μl or 15 μmol/L progesterone. Results:Spermatozoa exhibited acrosome reaction (41. 0± 1. 4%～48.0士1.4%),regardless of themedium in which they were resuspended. About 61%～67%of spermatozoa showed“B” pattern charac-teristic of capacitated sperm ),as monitored by the chlortetracycline assay.If spermatozoa were first incu-bated in mT-H and then resuspended in variotus media, they were unable to undergo AR in response to ZPor P(14. 0±3.6%～24.7±0.6%),even in mT-B25. This indicated that spermatozoa were not capacitat-ed and the proportion of“B”pattern spermatozoa in mT-H was lower (22%～33%).Conclusion : The results demonstrate that bicarbonate is essential for the acquisition of capacitation, butis not required for the acrosome reaction.