Ionic mechanism of the H+ pump in a snail neurone
Ionic mechanism of the H+ pump in a snail neurone
复制标题
蜗牛神经元 H 泵的离子机制
作者：
R. Thomas
观察到的神经和肌肉细胞内的pH值太高，不能用H+在细胞膜上的被动分布来解释1 -4。因此，有一个系统被认为是临时命名为H+或质子泵，它将H+从细胞中运输出来，或将OH-或HCO 3-运输到细胞中。尽管它的重要性，很少有人知道这个系统，也许是因为它不容易使用放射性同位素进行研究，使用它已经产生了很多关于更好地了解钠泵的信息。研究H+泵的一种方法是用pH敏感微电极跟踪细胞内pH（pHi）：因为类似的Na+敏感微电极可用于研究Na泵，所以也可以使用基本相同的方法在相同的制剂中比较两种泵。因此，凹尖型pH-敏感3或Na+-敏感5微电极可用于记录细胞中的pH或细胞内Na+（[Na+]i），例如蜗牛神经元，其足够坚韧以允许酸或Na盐的细胞内离子电渗注射。我在这里报告的实验中，H+泵的机制进行了研究，通过比较pH值的响应HCl注射与响应[Na+]i NaCl注射。
THE observed values of pH inside nerve and muscle cells are too high to be explained by a passive distribution of H+ across the cell membrane1–4. Thus there is believed to be a system, provisionally named a H+ or proton pump, which transports H+ out of, or OH− or HCO3− into the cell. In spite of its importance, little is known about this system, perhaps because it cannot easily be studied using radioisotopes, the use of which has yielded much information about the far better known Na pump. One way the H+ pump can be investigated is by following intracellular pH (pHi) with a pH-sensitive microelectrode: because a similar Na+-sensitive microelectrode can be used to study the Na pump, it is also possible to compare the two pumps in the same preparation using essentially the same methods. Thus the recessed-tip type of pH-sensitive3 or Na+-sensitive5 microelectrode can be used to record pHi or intracellular Na+ ([Na+]i) in cells, such as snail neurones, which are tough enough to permit intracellular iontophoretic injections of acid or Na salts. I report here experiments in which the mechanism of the H+ pump has been investigated by comparing the response of pHi to HCl injection with the response of [Na+]i to NaCl injection.