Antonenko Y N, Kinnally K W, Tedeschi H
Department of Biological Sciences, State University of New York, Albany 12222.
J Membr Biol. 1991 Nov;124(2):151-8. doi: 10.1007/BF01870459.
Alkalinization of the matrix side of the mitochondrial inner membrane by pH shifts from 6.8 to 8.3 caused a reversible increase in current of 3.2 +/- 0.2 pA (mean +/- SE, n = 21) at +/- 40 mV measured using patch-clamp techniques. The current increase was reversed in a graded fashion by the addition of Mg2+ as well as a reduction in pH. Detection of single-channel events was done at 0.5, 1 and 2 M KCl. The single-channel amplitude in 0.15 M KCl corresponds to approximately 15 pS. Reversal potentials derived from whole patch currents indicated that the inner mitochondrial membrane was primarily cation selective at pH 6.8 with a PK/PCl = 32 (n = 6). Treatment with alkaline pH (8.3) increased the current and anion permeability (PK/PCl = 16, n = 6). The membrane becomes completely cation selective when low concentrations (12 microM) of the drug propranolol are added. The amphiphilic drugs amiodarone (4 microM), propranolol (70 microM) and quinine (0.6 mM) blocked almost all of the current. The pH-dependent current was also inhibited by tributyltin. These results are consistent with the presence of two pathways in the inner mitochondrial membrane. One is cation selective and generally open and the other is anion selective and induced by alkaline pH. The alkaline pH-activated channel likely corresponds to the inner membrane anion channel postulated by others from suspension studies.
通过将pH从6.8转变为8.3使线粒体内膜基质侧碱化，使用膜片钳技术在±40 mV测量时，电流出现了3.2±0.2 pA（平均值±标准误，n = 21）的可逆增加。加入Mg2+以及降低pH可使电流增加呈梯度逆转。在0.5、1和2 M KCl条件下检测单通道事件。在0.15 M KCl中，单通道电流幅度约为15 pS。从全细胞膜片电流得出的反转电位表明，线粒体内膜在pH 6.8时主要对阳离子有选择性，PK/PCl = 32（n = 6）。用碱性pH（8.3）处理会增加电流和阴离子通透性（PK/PCl = 16，n = 6）。当加入低浓度（12 μM）的药物普萘洛尔时，膜变为完全阳离子选择性。两亲性药物胺碘酮（4 μM）、普萘洛尔（70 μM）和奎宁（0.6 mM）几乎阻断了所有电流。pH依赖性电流也受到三丁基锡的抑制。这些结果与线粒体内膜中存在两条途径一致。一条对阳离子有选择性且通常开放，另一条对阴离子有选择性且由碱性pH诱导。碱性pH激活的通道可能与其他人从悬浮研究中推测的内膜阴离子通道相对应。
