Nishimura K
Nara Prefectural Livestock Experiment Station, Japan.
Biol Reprod. 1993 Sep;49(3):537-43. doi: 10.1095/biolreprod49.3.537.
The effects of intracellular free calcium (Ca2+) ions on the malate-aspartate shuttle were studied in slow-cooled boar spermatozoa. The capacity of the malate-aspartate shuttle was assessed by an indirect method on the basis of accumulation of lactate relative to pyruvate when ethanol is provided as substrate. The capacity of the malate-aspartate shuttle at 37 degrees C was dependent on the presence of Ca2+ ions and was stimulated by an influx of Ca2+ ions induced by the combination of the Ca2+ ionophore A23187 and 100 microM CaCl2. When washed spermatozoa were cooled slowly to 15 degrees C, the percentage of progressive motile spermatozoa was about half that at 37 degrees C in 100 microM Ca(2+)-containing medium, while the capacity of the malate-aspartate shuttle remained equal to that at 37 degrees C. The motility decreased further at higher concentrations of Ca2+ ions. Spermatozoa in EGTA-containing medium barely moved at 15 degrees C and the capacity of the malate-aspartate shuttle decreased. Even in Ca(2+)-containing medium, LaCl3 caused a decrease in the capacity of the malate-aspartate shuttle at 15 degrees C. These results suggest that an influx of a low concentration of Ca2+ ions activates the malate-aspartate shuttle at 15 degrees C, with a subsequent increase in the proportion of cells that maintain progressive motility.
在缓慢冷却的公猪精子中研究了细胞内游离钙离子（Ca2+）对苹果酸 - 天冬氨酸穿梭系统的影响。当以乙醇作为底物时，基于乳酸相对于丙酮酸的积累，通过间接方法评估苹果酸 - 天冬氨酸穿梭系统的能力。37℃时苹果酸 - 天冬氨酸穿梭系统的能力取决于Ca2+离子的存在，并受到Ca2+离子载体A23187与100μM CaCl2组合诱导的Ca2+离子内流的刺激。当洗涤后的精子缓慢冷却至15℃时，在含100μM Ca2+的培养基中，进行性运动精子的百分比约为37℃时的一半，而苹果酸 - 天冬氨酸穿梭系统的能力保持与37℃时相等。在更高浓度的Ca2+离子下，运动能力进一步下降。含EGTA的培养基中的精子在15℃时几乎不运动，苹果酸 - 天冬氨酸穿梭系统的能力下降。即使在含Ca2+的培养基中，LaCl3也会导致15℃时苹果酸 - 天冬氨酸穿梭系统的能力下降。这些结果表明，低浓度Ca2+离子的内流在15℃时激活苹果酸 - 天冬氨酸穿梭系统，随后保持进行性运动的细胞比例增加。
