Oda S, Morisawa M
Misaki Marine Biological Station, University of Tokyo, Kanagawa, Japan.
Cell Motil Cytoskeleton. 1993;25(2):171-8. doi: 10.1002/cm.970250206.
Spermatozoa of marine teleosts, puffers and flounder, were completely quiescent when they were washed to remove electrolytic components of the seminal plasma and then diluted in nonelectrolyte solutions isotonic to the seminal plasma. Sperm motility was initiated upon dilution in hypertonic nonelectrolyte solutions. These observations suggest that sperm motility is suppressed by seminal osmolality and motility is triggered solely by the increase in external osmolality which occurs at natural spawning in hypertonic seawater. Extracellular Ca2+ had no influence on the osmolality-dependent initiation of sperm motility. However, sperm motility was initiated even in isotonic solution when Ca2+ was introduced into the sperm cells by Ca2+ ionophore. Intracellular Ca2+ increased at the osmolality-dependent initiation of sperm motility under Ca(2+)-free conditions. These results suggest that the release of Ca2+ from intracellular storage in response to the increase in external osmolality has a key role in the initiation of sperm motility. A transient increase in intracellular pH was also observed at the hyperosmolality-dependent initiation of sperm motility. Furthermore, initiation of sperm motility was induced even in isotonic solutions when intracellular pH increased by the treatment with ammonium salts. These results suggest that an increase in intracellular pH, as well as the rise in intracellular Ca2+, has an important role in the initiation of sperm motility in marine teleosts.
海洋硬骨鱼、河豚和比目鱼的精子，在洗去精浆中的电解质成分并在与精浆等渗的非电解质溶液中稀释后，会完全静止。在高渗非电解质溶液中稀释时，精子开始运动。这些观察结果表明，精子运动受到精浆渗透压的抑制，而运动仅由在高渗海水中自然产卵时发生的外部渗透压升高所触发。细胞外Ca2+对渗透压依赖性的精子运动启动没有影响。然而，当通过Ca2+离子载体将Ca2+引入精子细胞时，即使在等渗溶液中精子也会开始运动。在无Ca(2+)条件下，渗透压依赖性的精子运动启动时，细胞内Ca2+增加。这些结果表明，响应外部渗透压升高，细胞内储存的Ca2+释放对精子运动的启动起关键作用。在高渗依赖性的精子运动启动时，还观察到细胞内pH的短暂升高。此外，当用铵盐处理使细胞内pH升高时，即使在等渗溶液中也会诱导精子运动启动。这些结果表明，细胞内pH的升高以及细胞内Ca2+的升高，在海洋硬骨鱼精子运动的启动中起重要作用。
