Membrane hyperpolarization by sperm-activating and -attracting factor increases cAMP level and activates sperm motility in the ascidian Ciona intestinalis
Membrane hyperpolarization by sperm-activating and -attracting factor increases cAMP level and activates sperm motility in the ascidian Ciona intestinalis
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DOI：
10.1006/dbio.1999.9367
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发表时间：
1999-09-15
影响因子：
2.7
通讯作者：
Morisawa, M
中科院分区：
文献类型：
--
作者：
Izumi, H;Márián, T;Morisawa, M
在海鞘Ciona Ciona（和C. Savignyi），精子激活和吸引因子（SAAF）在受精时从卵中释放，并刺激精子的Ca 2+内流和cAMP水平的瞬时增加，导致精子活力的激活（M. Yoshida等人，1994年，德夫。增长差异。36，589-595）。在本文中，我们显示在C。证实缬氨霉素，钾离子选择性载体，以及SAAF，激活精子活力，这种激活被细胞外高K+抑制。膜电位测量结果表明，SAAF和缬氨霉素增加RC的精子通透性，并诱导膜超极化，其幅度取决于外部K+浓度。没有SAAF的玻璃海鞘精子的膜电位和细胞内K+浓度估计分别为约-50 mV和560 +/- 40 mM。在人工海水中，经SAAF或缬氨霉素处理后，细胞膜电位接近K ~+平衡电位（-100 mV），cAMP水平升高。一个有效的电压依赖性RC通道阻滞剂，MCD肽，在10 μ M的浓度阻止SAAF诱导的超极化的细胞，增加cAMP，和精子活力。这些结果表明，膜超极化产生的开放的K+通道提高cAMP的合成，并导致激活的精子活力在玻璃海鞘。(C)北京：科学出版社.
In the ascidian Ciona intestinalis (and C. savignyi), sperm-activating and -attracting factor (SAAF) is released from the egg at fertilization and stimulates both Ca2+ influx and a transient increase in cAMP level of the sperm, leading to the activation of sperm motility (M. Yoshida et al., 1994, Dev. Growth Differ. 36, 589-595). In this paper we show in C. intestinalis that valinomycin, a potassium-selective ionophore, as well as SAAF, activated sperm motility, and this activation was suppressed by extracellular high K+. Membrane potential measurements showed that both SAAF and valinomycin increase RC permeability of sperm and induce membrane hyperpolarization, the amplitude of which depends on the external K+ concentration. The membrane potential and intracellular K+ concentration of Ciona sperm without SAAF were estimated to be about -50 mV and 560 +/- 40 mM, respectively. After treatment with SAAF or valinomycin the membrane potential became almost equal to the equilibrium potential of K+ (-100 mV), and the cAMP level increased in artificial seawater. A potent voltage-dependent RC channel blocker, MCD peptide, at the concentration of 10 mu M blocked SAAF-induced hyperpolarization of the cells, increase in cAMP, and sperm motility. These results suggest that membrane hyperpolarization produced by the opening of K+ channels elevates cAMP synthesis and leads to the activation of sperm motility in Ciona. (C) 1999 Academic Press.