期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：13
页码：6001-6005
DOI：10.1073/pnas.89.13.6001
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Transduction by sperm of the instructive signal provided by the egg peptide speract involves rapid, complex changes in internal ion and cyclic nucleotide content. Here, investigations of hypotonically swollen sperm provide insight into the underlying processes and identify K+ channel activation as an initial ionic event in gamete recognition. A sustained hyperpolarization of swollen sperm is promoted by less than 2.5 pM speract and is followed (with greater than 100 pM speract) by transient repolarization and (with greater than 10 nM speract) by depolarization that is dependent on external Ca2+. Monophasic increases in pHi are produced only by greater than 25 pM speract, indicating that hyperpolarization may not directly promote alkalinization. Increased K(+)-selective (K+ greater than Rb+ greater than Cs+ greater than Na+) membrane permeability is found after all speract greater than 2.5 pM, suggesting that hyperpolarization results from persistent activation of K+ channels and that repolarization has a different ionic basis. Supporting this contention, the K+ channel blocker tetraethylammonium (20 mM) inhibits the increased K+ permeability that follows treatment of swollen sperm (and of sperm in seawater) with 2.5 pM speract. Such induced activation of K+ channels is observed in patch-clamped swollen sperm examined in the cell-attached configuration, upon application of 5-50 pM speract to the bath medium. The efficacy of externally applied speract and its potency indicate that activation is indirect and probably involves an as yet unidentified diffusible mediator whose production is promoted by speract at concentrations 0.01-0.001 times those predicted from reported estimates of the Kd for the known speract receptor.
