A DEPOLARIZATION CAN TRIGGER CA2+ UPTAKE AND THE ACROSOME REACTION WHEN PRECEDED BY A HYPERPOLARIZATION IN L-PICTUS SEA-URCHIN SPERM
A DEPOLARIZATION CAN TRIGGER CA2+ UPTAKE AND THE ACROSOME REACTION WHEN PRECEDED BY A HYPERPOLARIZATION IN L-PICTUS SEA-URCHIN SPERM
复制标题
DOI：
10.1016/0012-1606(92)90018-c
复制
发表时间：
1992-03-01
影响因子：
2.7
通讯作者：
DARSZON, A
中科院分区：
文献类型：
--
作者：
GONZALEZMARTINEZ, MT;GUERRERO, A;DARSZON, A
顶体反应（AR）是一种胞吐事件，允许精子识别并与卵子融合。在海胆精子中，这种反应是由卵的外部投资触发的，果冻，其诱导离子运动，导致细胞内Ca 2+（[Ca 2 +]i）和细胞内pH（pHi）增加，K+依赖性瞬时超极化（可能涉及K+通道）和去极化（依赖于外部Ca 2+）。本文探讨了超极化在顶体反应触发中的作用。在无钾海水中用缬氨霉素人工超极化苦海龙，使pHi升高，45 Ca ~（2+）摄取量略有增加，并引发一定程度的AR。在诱导超极化后40-60秒用KCl（30 mM）去极化，pHi降低，45 Ca ~（2+）摄取、[Ca ~（2+）]i和AR显著增加。为了允许AR发生所需的pH变化，该等待时间是必要的。因此，肾上腺素诱导的超极化可能导致触发AR所需的细胞内碱化，并且，其本身或通过pHi，可能调节参与该过程的Ca 2+转运系统。由于K+在AR的触发中起着关键作用，L.人们正在探索精子质膜的图像分离。平面脂质双层，这些膜被纳入融合显示85 pS的单通道转换是阳离子选择性的。
The acrosome reaction (AR) is an exocytotic event that allows sperm to recognize and fuse with the egg. In the sea urchin sperm this reaction is triggered by the outer investment of the egg, the jelly, which induces ionic movements leading to increases in intracellular Ca2+([Ca2+]i) and intracellular pH (pHi), a K+-dependent transient hyperpolarization which may involve K+channels, and a depolarization which depends on external Ca2+. The present paper explores the role of the hyperpolarization in the triggering of the acrosome reaction. The artificial hyperpolarization ofLytechinus pictussperm with valinomycin in K+-free seawater raised the pHi, caused a small increase in45Ca2+uptake, and triggered some AR. When the cells were depolariźed with KCl (30 mM) 40–60 sec after the induced hyperpolarization, the pHidecreased and there was a significant increase in45Ca2+uptake, [Ca2+]i, and the AR. This waiting time was necessary in order to allow the pHichange required for the AR to occur. Thus, the jelly-induced hyperpolarization may lead to the intracellular alkalinization required to trigger the AR, and, on its own or via pHi, may regulate Ca2+transport systems involved in this process. Because of the key role played by K+in the triggering of the AR, the presence and characteristics of ion channels inL. pictusisolated sperm plasma membranes are being explored. Planar lipid bilayers into which these membranes were incorporated by fusion displayed 85 pS single channel transitions which were cation selective.