Gong X D, Li J C H, Leung G P H, Cheung K H, Wong P Y D
Department of Physiology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
Biol Reprod. 2002 Jul;67(1):46-54. doi: 10.1095/biolreprod67.1.46.
Spermatogenesis is a complex cellular event during which the diploid germ cells differentiate and divide by mitosis and meiosis at specific time points along the spermatogenic cycle to generate the haploid spermatozoa. For this complex event to go in an orderly manner, cell differentiation and division must be precisely controlled by signals arising from within and outside the seminiferous tubules. Changes in the membrane potential of the germ cells are likely to be an important part of the signaling mechanism. We have applied the whole-cell patch clamp technique to identify and characterize ion channels in different spermatogenic cells from immature and mature rat testes fractionated by discontinuous Percoll gradient. A voltage- and Ca(2+)- dependent, outwardly rectifying current with gating and pharmacologic properties resembling the large conductance K(+) channels (BK(Ca)) was recorded from the spermatogonia and primary spermatocytes. Another voltage-dependent, outwardly rectifying current that was sensitive to 4-aminopyridine, a K(v) channel blocker, was detected in spermatocytes and early spermatids. This current is likely caused by the smaller conductance, voltage-sensitive K(+) channels (K(v)). In some spermatogonia, both the BK(Ca) channels and the K(v) channels could be simultaneously detected in the same cell. It appears that during the course of spermatogenesis, there is up-regulation of K(v) but down-regulation of BK(Ca). Reverse transcription-polymerase chain reaction, Western blot analysis, and immunohistochemistry further confirmed the differential expression of the ion channels in different spermatogenic cells. We conclude that these ion channels may play an important role in the control of spermatogenesis.
精子发生是一个复杂的细胞事件，在此过程中，二倍体生殖细胞在生精周期的特定时间点通过有丝分裂和减数分裂进行分化和分裂，以产生单倍体精子。为了使这个复杂的事件有序进行，细胞的分化和分裂必须由来自曲细精管内外的信号精确控制。生殖细胞膜电位的变化可能是信号传导机制的重要组成部分。我们应用全细胞膜片钳技术，对通过不连续Percoll梯度分离的未成熟和成熟大鼠睾丸的不同生精细胞中的离子通道进行鉴定和表征。从精原细胞和初级精母细胞中记录到一种电压和Ca(2+)依赖性的外向整流电流，其门控和药理学特性类似于大电导钾通道（BK(Ca)）。在精母细胞和早期精子细胞中检测到另一种对钾通道阻滞剂4-氨基吡啶敏感的电压依赖性外向整流电流。这种电流可能由较小电导的电压敏感性钾通道（K(v)）引起。在一些精原细胞中，同一细胞内可同时检测到BK(Ca)通道和K(v)通道。在精子发生过程中，似乎存在K(v)通道上调而BK(Ca)通道下调的情况。逆转录-聚合酶链反应、蛋白质印迹分析和免疫组织化学进一步证实了不同生精细胞中离子通道的差异表达。我们得出结论，这些离子通道可能在精子发生的控制中起重要作用。
