Intracellular pH regulation by vertebrate muscle.
Intracellular pH regulation by vertebrate muscle.
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脊椎动物肌肉的细胞内 pH 调节。
DOI：
10.1146/annurev.ph.48.030186.002025
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发表时间：
1986
影响因子：
18.2
通讯作者：
C. Aickin
中科院分区：
文献类型：
--
作者：
C. Aickin
面对挛缩引起的酸中毒时，pHi 的调节似乎对肌肉细胞的生理学至关重要，以至于所有肌肉类型共有的过程似乎是一个合理的预测。然而，尚未发现情况确实如此。跨膜 Na+ 梯度显然起着重要作用，并且该过程在所有三类肌肉中似乎都是电中性的，但即使在哺乳动物内部，转运机制也是不同的。一个有趣的观察是，在 CO2 存在的情况下，肌肉细胞调节 pHi 的能力（可能由 PHCO3 控制）与 PCl 相关，尽管几乎没有证据表明 HCO3- 通过 Cl- 通道渗透。在正常极化的青蛙骨骼肌中，几乎没有观察到 CO2 诱导的酸中毒的恢复，其中 PCl 形成了静息电导的很大一部分，而在哺乳动物平滑肌中，在不同 CO2 水平存在的情况下记录了相同的稳态 pHi，其中 PCl 非常低。脊椎动物肌肉 pHi 调节的研究为整个学科提供了重要的教训。心肌经验表明，如果存在 Na+-Ca2+ 交换，则在解释跨膜 Na+ 梯度改变或 Ca2+ 水平改变的结果时需要非常小心。考虑到最近的报道称 Ca2+ 抑制 Na+-H+ 交换，解释可能会更加复杂。 “确实，”这样的结论似乎是恰当的，“如果一点点知识都是危险的，那么拥有那么多知识足以摆脱危险的人在哪里呢？” （托马斯·赫胥黎）。
Regulation of pHi in the face of acidosis resulting from contracture would appear to be of such fundamental importance to the physiology of the muscle cell that a process common to all muscle types seems a reasonable prediction. However, this has not been found to be the case. The transmembrane Na+ gradient clearly plays a major role and the process appears to be electroneutral in all three classes of muscle, but the transport mechanisms, even within the mammal, are different. It is an interesting observation that the ability of the muscle cell to regulate pHi in the presence of CO2, presumably governed by PHCO3, is related to PCl although there is little evidence for HCO3- permeation through Cl- channels. Virtually no recovery from CO2-induced acidosis is observed in normally polarized frog skeletal muscle, where PCl forms a large part of the resting conductance, whereas the same steady state pHi is recorded in the presence of various CO2 levels in mammalian smooth muscle, where PCl is very low. The study of pHi regulation in vertebrate muscle has provided important lessons for the subject as a whole. Experience in cardiac muscle has shown that if Na+-Ca2+ exchange is present, great care is required in interpretation of results where the transmembrane Na+ gradient is altered or where Ca2+ levels are changed. Interpretation may be even more complex, bearing in mind the recent reports that Ca2+ inhibits Na+-H+ exchange. "Indeed," it seems appropriate to conclude, "if a little knowledge is dangerous, where is the man who has so much as to be out of danger?" (Thomas Huxley).