Fraser L R, McDermott C A
Biomedical Sciences Division, King's College London, Strand, UK.
J Reprod Fertil. 1992 Sep;96(1):363-77. doi: 10.1530/jrf.0.0960363.
Mammalian spermatozoa require extracellular Ca2+, some of which must be internalized, to undergo complete capacitation. At a critical threshold, a rise in intracellular Ca2+ will trigger acrosomal exocytosis. We used chlortetracycline (CTC) fluorescence patterns to assess changes in the capacitation state of mouse spermatozoa after incubation under various conditions that would affect their intracellular Ca2+ concentrations. Under standard conditions with 1.80 mmol CaCl2l-1 known to support capacitation within 120 min and subsequent fertilization in vitro, a rise in the number of capacitated, acrosome-intact cells (B pattern) was observed over the first 60 min, followed by a decline. A detectable increase in capacitated, acrosome-reacted cells (AR pattern) coincided with the maximum of B pattern cells and a continued rise was observed over the following 60 min. With incubation in 3.60 mmol Ca2+l-1, the rise in AR cells began at 30 min, suggesting that this treatment accelerates capacitation. Introduction of ionophore A23187 at 15 min to cells in standard Ca2+ produced a similar but even more rapid response, with a maximum in B pattern cells and a noticeable rise in AR cells within 10 min. Thus ionophore-treated cells proceed through capacitation, but do so very quickly. However, ionophore in the presence of 90 mumol Ca2+l-1 could promote transition from the uncapacitated F pattern to the capacitated B pattern, but could not trigger acrosomal exocytosis, indicating that the latter requires high extracellular Ca2+. After preincubation in Ca(2+)-deficient medium, most cells exhibited the uncapacitated F pattern and the introduction of millimolar Ca2+ altered this distribution only slowly, over a period of 50 min. In contrast, preincubation in 90 mumol Ca2+l-1 resulted in a minority of F pattern cells and, within 10 min of millimolar Ca2+ introduction, a significant increase in AR cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
哺乳动物的精子需要细胞外的Ca2+，其中一些必须内化，才能完成获能。在一个关键阈值时，细胞内Ca2+的升高会触发顶体胞吐作用。我们使用金霉素（CTC）荧光模式来评估小鼠精子在各种会影响其细胞内Ca2+浓度的条件下孵育后获能状态的变化。在已知能在120分钟内支持获能及随后体外受精的1.80 mmol CaCl2l-1标准条件下，在最初60分钟内观察到获能的、顶体完整细胞（B模式）数量增加，随后下降。获能的、顶体反应细胞（AR模式）的可检测增加与B模式细胞的最大值同时出现，并在接下来的60分钟内持续上升。在3.60 mmol Ca2+l-1中孵育时，AR细胞的增加在30分钟时开始，表明这种处理加速了获能。在标准Ca2+条件下于15分钟向细胞中引入离子载体A23187产生了类似但更快速的反应，B模式细胞达到最大值，AR细胞在10分钟内显著增加。因此，经离子载体处理的细胞通过获能过程，但速度非常快。然而，在90 μmol Ca2+l-1存在下的离子载体可促进从未获能的F模式向获能的B模式转变，但不能触发顶体胞吐作用，这表明后者需要高细胞外Ca2+。在Ca2+缺乏的培养基中预孵育后，大多数细胞呈现未获能的F模式，引入毫摩尔浓度的Ca2+只会在50分钟的时间内缓慢改变这种分布。相比之下，在90 μmol Ca2+l-1中预孵育导致少数F模式细胞，并且在引入毫摩尔浓度的Ca2+后10分钟内，观察到AR细胞显著增加。（摘要截断于250字）
