Methylxanthines stimulate calcium transport and inhibit cyclic nucleotide phosphodiesterases in abalone sperm.
Methylxanthines stimulate calcium transport and inhibit cyclic nucleotide phosphodiesterases in abalone sperm.
复制标题
甲基黄嘌呤刺激钙转运并抑制鲍鱼精子中的环核苷酸磷酸二酯酶。
DOI：
10.1016/0012-1606(83)90258-0
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发表时间：
1983
影响因子：
2.7
通讯作者：
Vacquier,VD
中科院分区：
文献类型：
--
作者：
Kopf,GS;Lewis,CA;Vacquier,VD
实验旨在确定甲基黄嘌呤提高鲍鱼精子cAMP浓度并诱导顶体反应(AR)的机制。茶碱或更有效的1-甲基-3-异丁基黄嘌呤(MIX)抑制鲍鱼精子匀浆的环核苷酸磷酸二酯酶活性。45Ca2+的摄取也被茶碱刺激，MIX更有效，这种刺激作用被KCN阻断。维拉帕米是一种已知的拮抗钙离子电导的化合物，在200μM以下对钙离子或混合离子诱导的cAMP升高没有影响，但维拉帕米降低了添加钙++混合离子引起的精子cAMP升高。这种抑制作用并不完全，即使在200μ的米维拉帕米。200μ米维拉帕米可完全抑制钙+混合液诱发的AR。这些数据表明，这些甲基黄嘌呤通过抑制环核苷酸磷酸二酯酶活性来提高鲍鱼精子的环核苷酸浓度。此外，由于精子cAMP代谢受Ca~(2+)流量的调节，甲基黄嘌呤似乎也通过其对Ca~(2+)转运的影响来提高鲍鱼精子cAMP浓度。钙离子诱导的cAMP升高是通过维拉帕米不敏感的机制实现的，而钙离子对cAMP升高的增强作用是通过维拉帕米不敏感和不敏感两种机制实现的。甲基黄嘌呤诱导的AR是通过对钙离子转运的主要作用介导的，并通过维拉帕米敏感的机制发生。环磷酸腺苷可能在甲基黄嘌呤诱导的AR中起作用，但似乎不是这种胞吐事件的主要介体。
Experiments were designed to determine the mechanism by which methylxanthines elevate abalone sperm cAMP concentrations and induce the acrosome reaction (AR). Theophylline or, more effectively, 1-methyl-3-isobutylxanthine (MIX) inhibit the cyclic nucleotide phosphodiesterase activities of abalone sperm homogenates.45Ca2+uptake by sperm is also stimulated by theophylline, and more effectively by MIX, and this stimulatory effect is blocked by KCN. Verapamil, a compound known to antagonize Ca2+conductance, has no effect on the Ca2+or MIX-induced cAMP elevation at concentrations up to 200 μM. However, verapamil reduces the sperm cAMP elevation caused by the addition of Ca2+plus MIX. This inhibition is not complete, even at 200 μMverapamil. The AR induced by Ca2+plus MIX is completely inhibited by 200 μMverapamil. The data suggest that these methylxanthines elevate abalone sperm cyclic nucleotide concentrations by inhibiting cyclic nucleotide phosphodiesterase activities. Furthermore, since sperm cAMP metabolism is modulated by Ca2+flux, methylxanthines also appear to elevate abalone sperm cAMP concentrations by their effects on Ca2+transport. The Ca2+-induced cAMP elevation occurs through a verapamil-insensitive mechanism, whereas the potentiation by MIX of the Ca2+effect to elevate cAMP occurs through both verapamil-insensitive and -sensitive mechanisms. The methylxanthine-induced AR is mediated by a primary effect on Ca2+transport and occurs through a verapamil-sensitive mechanism. Cyclic AMP may play a role in the methylxanthine-induced AR, but does not appear to act as the primary mediator of this exocytotic event.