NH4+ conductance inxXenopus laevis oocytes.: III.: Effect of NH3
NH4+ conductance inxXenopus laevis oocytes.: III.: Effect of NH3
复制标题
DOI：
10.1007/s00424-003-1122-z
复制
发表时间：
2003-09-01
影响因子：
4.5
通讯作者：
Burckhardt, BC
中科院分区：
文献类型：
--
作者：
Boldt, M;Burckhardt, G;Burckhardt, BC
非洲爪蟾卵母细胞暴露于NH 4Cl引起细胞内酸化，细胞膜去极化和产生的内向电流。为了确定不带电荷的NH3和带正电荷的NH 4+的贡献，在恒定[NH 4Cl]（10 mM）下增加[NH3]或在恒定[NH3]（0.045 mM）下增加[NH 4Cl]的情况下测量NH 4Cl诱导的内向电流，其中在两种情况下pH变化。在-70 mV下，在pH 6.5、0.01 mM NH3下几乎检测不到NH 4Cl诱导的电流，但在pH 7.5、0.1 mM NH3和pH 8.5、1 mM NH3下连续增加。与此相反，NH 4Cl相关的电流是独立的变化的[NH 4Cl]在恒定的[NH3]和可变pH值。类似的结果与酸化，去极化和内向电流响应浓度和pH值的变化，得到与盐酸三甲胺。增加浓度的弱酸性丙酸导致的NH 4Cl诱导的电流的减少。这些数据表明，NH3进入可能会引起局部碱化，反过来，可能会触发开放的电导NH 4+或三甲胺-H+的进入。
Exposure of Xenopus laevis oocytes to NH4Cl caused intracellular acidification, cell membrane depolarization and the generation of an inward current. To determine the contribution of uncharged NH3 and positively charged NH4+, the NH4Cl-induced inward current was measured in the presence of increasing [NH3] at constant [NH4Cl] (10 mM) or increasing [NH4Cl] at constant [NH3] (0.045 mM) with pH varying in both cases. At -70 mV, the NH4Cl-induced current was barely detectable at pH 6.5, 0.01 mM NH3, but increased successively at pH 7.5, 0.1 mM NH3 and pH 8.5, 1 mM NH3. In contrast, NH4Cl-associated currents were independent of changes of the [NH4Cl] at constant [NH3] and variable pH. Similar results with respect to acidification, depolarization and inward current in response to concentration and pH changes were obtained with trimethylamine HCl. Increasing concentrations of the weak acid propionate led to a reduction of the NH4Cl-induced current. These data suggest that NH3 entry may induce local alkalinization that, in turn, may trigger the opening of a conductance for NH4+ or trimethylamine-H+ entry.