Bicarbonate actions on flagellar and Ca2+-channel responses:: initial events in sperm activation
Bicarbonate actions on flagellar and Ca2+-channel responses:: initial events in sperm activation
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DOI：
10.1242/dev.00353
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发表时间：
2003-04-01
期刊：
影响因子：
4.6
通讯作者：
Babcock, DF
中科院分区：
文献类型：
--
作者：
Wennemuth, G;Carlson, AE;Babcock, DF
在交配时，哺乳动物的精子在雄性和雌性的生殖液中被稀释，这与HCO 3-接触并引发几种细胞反应。我们已经确定并研究了其中两种最迅速的反应。停搏运动成像和鞭毛波形分析表明，小鼠离体附睾精子在22- 25 ℃时，鞭毛的静息搏动频率为2-3 Hz。局部灌注HCO 3-产生一个强大的，可逆的加速到7赫兹或更高。在15 mM时，HCO 3-的作用在5秒内开始，并在30秒时接近最大值。在15 mM HCO 3-和1 mM HCO 3-条件下，响应半衰期分别为8.8+/-0.2秒和17.5+/-0.4秒。去除外部HCO 3-允许在大约10分钟内缓慢恢复到基础搏动频率。拍对称性的增加伴随着HCO 3-的加速作用。在我们过去的工作中，HCO 3-也促进开放的电压门控钙通道，增加去极化诱发率上升的细胞内钙离子浓度的五倍以上。这种作用在1 mMHCO 3-下也可检测到，在15 mMHCO 3-下发生的表观半衰期类似于60秒。HCO 3-的双重作用与药物干预的反应相似。因此，磷酸二酯酶抑制剂IBMX促进HCO 3-对鞭毛和通道功能的作用，而蛋白激酶A抑制剂H89阻断这些作用。此外，用60 μ M cAMP乙酰氧基甲酯孵育30分钟可使鞭毛搏动频率增加到接近7 Hz，并使细胞内Ca 2+浓度的诱发上升速率从17+/-4增加到41+/-6 nM秒（-1）。然而，治疗与其他几个类似物的cAMP产生的预期模仿或阻断HCO 3-的行动，可能是由于有限的渗透的证据很少。我们的研究结果表明，cAMP介导的蛋白磷酸化在增强鞭毛和通道功能，HCO 3-在精子激活过程中产生的要求。
At mating, mammalian sperm are diluted in the male and female reproductive fluids, which brings contact with HCO3- and initiates several cellular responses. We have identified and studied two of the most rapid of these responses. Stop-motion imaging and flagellar waveform analysis show that for mouse epididymal sperm in vitro, the resting flagellar beat frequency is 2-3 Hz at 22-25degreesC. Local perfusion with HCO3- produces a robust, reversible acceleration to 7 Hz or more. At 15 mM the action of HCO3- begins within 5 seconds and is near-maximal by 30 seconds. The half-times of response are 8.8+/-0.2 seconds at 15 mM HCO3- and 17.5+/-0.4 seconds at 1 mM HCO3-. Removal of external HCO3- allows a slow return to basal beat frequency over similar to10 minutes. Increases in beat symmetry accompany the accelerating action of HCO3-. As in our past work, HCO3- also facilitates opening of voltage-gated Ca2+ channels, increasing the depolarization-evoked rate of rise of intracellular Ca2+ concentration by more than fivefold. This action also is detectable at 1 mM HCO3-and occurs with an apparent halftime of similar to60 seconds at 15 mM HCO3-. The dual actions of HCO3- respond similarly to pharmacological intervention. Thus, the phosphodiesterase inhibitor IBMX promotes the actions of HCO3- on flagellar and channel function, and the protein kinase A inhibitor H89 blocks these actions. In addition, a 30 minute incubation with 60 muM cAMP acetoxylmethyl ester increases flagellar beat frequency to nearly 7 Hz and increases the evoked rates of rise of intracellular Ca2+ concentration from 17+/-4 to 41+/-6 nM second(-1). However, treatment with several other analogs of cAMP produces only scant evidence of the expected mimicry or blockade of the actions of HCO3-, perhaps as a consequence of limited permeation. Our findings indicate a requirement for cAMP-mediated protein phosphorylation in the enhancement of flagellar and channel functions that HCO3- produces during sperm activation.