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首页> 外文期刊>Biochemistry >MEMBRANE POTENTIAL REGULATES SEA URCHIN SPERM ADENYLYLCYCLASE
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MEMBRANE POTENTIAL REGULATES SEA URCHIN SPERM ADENYLYLCYCLASE

机译：膜电位调节海蛋白精子腺苷酸环化酶

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摘要

Adenylylcyclase (AC) from sea urchin sperm does not appear to be regulated by G proteins [Hildebrandt, J. D., Tash, J. S., Kirchick, H. J., Lipschunits, L., Secra, R. D., & Birmbaumer, L. (1985) Endocrinology, 116, 1357-1366]. During sperm activation and the acrosome reaction, membrane potential changes and cAMP increases. Here we explore if membrane potential can modulate the sperm AC. Hyperpolarization of Lytechinus pictus sea urchin sperm either with valinomycin in artificial sea water (ASW) without K+ or with dilution in ASW without Na+ increased the [c-AMP] (2.2- and 5.8-fold, respectively). This increase also occurred in the absence of extracellular Ca2+ (1.9- and 3.1-fold, respectively) and was enhanced by 100 mu M IBMX, a phosphodiesterase inhibitor. It has been suggested that sea urchin sperm AC is stimulated by increases in intracellular Ca2+ and intracellular pH. In ASW without Na+ and Ca2+ (0Na0CaASW), sea urchin sperm intracellular pH decreases, and intracellular Ca2+ cannot increase. Therefore, these observations taken together indicate that AC in these cells is modulated by membrane potential. Dilution of Strogylocentrotus purpuratus sperm in 0Na0CaASW hyperpolarized them and increased their cAMP levels (1.3-fold). This stimulation was enhanced by IBMX (1.6-fold). Addition of the egg peptide speract under this condition further hyperpolarized S. purpuratus sperm and synergistically increased [cAMP] above 0Na0CaASW. This stimulation became larger in the presence of IBMX (from 1.6- to 5.2-fold). Since speract cannot elevate intracellular pH or [Ca2+] in 0Na0CaASW, the increase in [cAMP] it causes must be due to sperm hyperpolarization.
机译：海胆精子的腺苷酸环化酶（AC）似乎不受G蛋白的调控[Hildebrandt，JD，Tash，JS，Kirchick，HJ，Lipschunits，L.，Secra，RD，和Birmbaumer，L.（1985）内分泌学，116 ，1357-1366]。在精子活化和顶体反应过程中，膜电位改变并且cAMP增加。在这里，我们探讨膜电位是否可以调节精子AC。在不带K +的人工海水（ASW）中加入缬氨霉素或在不带Na +的ASW中进行稀释，将扁豆对海胆精子进行超极化可增加[c-AMP]（分别为2.2倍和5.8倍）。这种增加也发生在不存在细胞外Ca2 +（分别为1.9倍和3.1倍）的情况下，并被100μM磷酸二酯酶抑制剂IBMX增强。已经提出，细胞内Ca 2+和细胞内pH的增加会刺激海胆精子AC。在没有Na +和Ca2 +（0Na0CaASW）的ASW中，海胆精子的细胞内pH值降低，并且细胞内Ca2 +不能增加。因此，这些观察结果共同表明，这些细胞中的交流电受膜电位的调节。在0Na0CaASW中稀释紫圆螺精子使它们超极化，并增加其cAMP水平（1.3倍）。 IBMX增强了这种刺激（1.6倍）。在这种条件下添加卵肽精子可进一步使紫癜链球菌的精子超极化，并在0Na0CaASW以上协同提高[cAMP]。在IBMX存在下，这种刺激变得更大（从1.6倍增加到5.2倍）。由于精子不能升高0Na0CaASW中的细胞内pH或[Ca2 +]，因此它引起的[cAMP]升高必须归因于精子超极化。

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