Regulation of intracellular pH by Ca²⁺ - activated proton channel

Abstract

Background and aim: We have characterized a membrane current associated with a decrease in pHi, which can be induced by either elevating intracellular calcium or extracellular application of methylmercury (a potent agent in elevating intracellular Ca²⁺ concentration) in the alveolar macrophages bathing in the impermeant bilateral cesium aspartate solution.

Results: Decreasing pHi and elevating [Ca²⁺]i profoundly enhanced, but H-7 (a broad-spectrum kinase inhibitor), W-7 (a selective calmodulin antagonist) and KN-93 (a calmodulin kinase II inhibitor) inhibited the currents.

Conclusion: These results indicate that rat alveolar macrophages possess a calcium-activated and pHi-sensitive proton channel which can be phosphorylated and activated by calmodulin kinase II.

Keywords::

• Methylmercury
• rat alveolar macrophage
• calcium
• proton current
• CaMkinase phosphorylation

Declaration of interest: This work was supported by research grants from the National Science Council, Republic of China, and the National Health Research Institute. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.