Dept of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T5G 2E9.
Comp Biochem Physiol A Mol Integr Physiol. 2010 Feb;155(2):139-45. doi: 10.1016/j.cbpa.2009.10.025. Epub 2009 Oct 24.
We have studied intracellular pH (pH(i)) recovery in isolated trout gill mitochondrion-rich (MR) cells following acidification by the NH(4)Cl pre-pulse technique. Within a mixed MR cell population, one cell type displayed Na(+)-independent pH(i) recovery while the other cell type lacked a Na(+)-independent pH(i) recovery. Cells displaying Na(+) independent recovery exhibited a significantly higher buffering capacity compared to cells lacking Na(+)-independent pH(i) recovery. Cells displaying Na(+) independent recovery were identified as PNA(+) (peanut lectin agluttinin binding) MR cells while those unable to recover were identified as PNA(-) (non-peanut lectin agluttinin binding) MR cells. Therefore, recovery from acidification in the absence of Na(+) provides a direct functional marker for PNA(+) and PNA(-) MR cells. Re-addition of Na(+) to acidified cells resulted in a transient pH(i) recovery in both cell types. This event was abolished by amiloride (500 microM) but it was insensitive to phenamil (50 microM). The phorbol ester PMA (1 microM) potentiated the Na(+) induced pH(i) recovery suggesting that activation by PKC is required for continuous Na(+)/H(+) exchanger activity in trout gill MR cells. This study is the first functional description of pH(i) recovery in lectin-identified trout gill MR cells and provides insight into a putative cellular signaling mechanism that may control pH(i) regulation in the gill epithelium.
我们研究了 NH4Cl 脉冲酸化后，分离的鳟鱼鳃富含线粒体（MR）细胞内 pH（pHi）的恢复情况。在混合的 MR 细胞群体中，一种细胞类型显示出 Na+非依赖性 pHi恢复，而另一种细胞类型则缺乏 Na+非依赖性 pHi恢复。与缺乏 Na+非依赖性 pHi恢复的细胞相比，显示 Na+非依赖性恢复的细胞具有更高的缓冲能力。显示 Na+非依赖性恢复的细胞被鉴定为 PNA+（花生凝集素结合）MR 细胞，而不能恢复的细胞被鉴定为 PNA-（非花生凝集素结合）MR 细胞。因此，在没有 Na+的情况下从酸化中恢复提供了 PNA+和 PNA-MR 细胞的直接功能标记。将 Na+重新添加到酸化的细胞中，导致两种细胞类型的 pHi短暂恢复。该事件被阿米洛利（500μM）消除，但对苯甲脒（50μM）不敏感。佛波酯 PMA（1μM）增强了 Na+诱导的 pHi恢复，表明 PKC 的激活是鳜鱼鳃 MR 细胞中连续 Na+/H+交换器活性所必需的。这项研究是首次对凝集素鉴定的鳜鱼鳃 MR 细胞中 pHi恢复的功能描述，并提供了对可能控制鳃上皮细胞 pHi调节的细胞信号机制的深入了解。
