[The influence of extracellular pH on volume-activated chloride current in the prostate cancer epithelial cells]

The influence of extracellular pH on characteristics of volume-activated chloride current, ICl,swell, in the human prostate cancer epithelial cell line, LNCaP, was studied using the patch-clamp technique. Acidification of the extracellular hypotonic solution used to develop the current shortened the temporal parameters of ICl,swell development and reduced its maximal density. Sudden shifts of the pH towards acidification caused fast, transient potentiation of the current followed by its sustained inhibition. Voltage-dependent inactivation of ICl,swell was the most pronounced in the narrow range of pH = 6-7. Based on the analysis of our data we hypothesize that volume-regulated anion channels underlying ICl,swell possess in their structure at least two pH-sensitive molecular groups with similar pK = 6, titration of which modulates the current amplitude and two additional proton-sensitive groups that determine channel's inactivation.