Functions of vacuolar H+-ATPases and voltage-gated proton channels coexisted in the plasma membrane of osteoclasts

破骨细胞在质膜上表达两种类型的生电H+选择性转运机制，即液泡H+-ATP酶（V-ATP酶）和电压门控质子通道。在全细胞钳位结构下，在单个细胞中鉴定这些H+电流，我们发现在生理细胞内pH（>7.0）和膜电位（<-20 mV）下，V-ATP酶占主导地位，但是在高于激活阈值的电压下，通过H+通道的H+流出超过V-ATP酶，这表明这两种机制迅速转换它们的角色。通过V-ATP酶的细胞内pH的增加抑制附近的H+通道的激活，但反之亦然。细胞内pH值的升高，无论是弱碱或V-ATP酶，促进动力蛋白依赖的内吞内化的H+通道。这些数据提出了H+通道储备池的概念，并提出了破骨细胞中V-ATP酶与H+通道相互作用的新机制。

Osteoclasts express two types of electrogenic H+-selective transport mechanisms at the plasma membrane, that is, vacuolar H+-ATPases (V-ATPases) and voltage-gated proton channels. Identifying these H+ currents in single cells under the whole-cell clamp configuration, we showed that V-ATPases were predominant at physiological intracellular pH (>7.0) and membrane potentials (<-20 mV), but that H+ efflux via the H+ channels exceeded those of V-ATPases at voltages higher than the activation threshold, suggesting that the two mechanisms switch their roles quickly. The increase in intracellular pH via V-ATPases inhibited activation of nearby H+ channels, but not vice versa. Elevation of intracellular pH, either by weak bases or V-ATPases, facilitated dynamin-dependent endocytic internalization of H+ channels. The data presented an idea of the reserving pool for H+ channels and suggested novel mechanisms for interaction between V-ATPases and H+ channels in osteoclasts.