Coupled Activation of Mechanosensitive and Calcium-Dependent Potassium Channels in 3T3 and 3T3-SV40 Cells

Abstract

Using the patch–clamp method, mechanosensitive regulation of ion channels was studied in cultivated 3T3 and 3T3-SV40 fibroblasts. The activity of mechanosensitive cation channels with a conductivity 25 pS in response to plasma-membrane stretching was observed in both cell lines. Despite obvious differences in the actin network in normal and transformed cells, the threshold values of the stimulus required for the channel activation were close and were approximately 55 mm Hg. The frequency of channels was significantly higher in transformed 3T3-SV40 fibroblasts than in their untransformed 3T3 analogs. Coupled activation of mechanosensitive calcium-permeable channels and potassium calcium-controlled channels was found in both cell lines. The analysis of flows through single channels allows to detect functional interaction of different channels: stretch-induced local calcium entry activates potassium channels that do not have their own mechanosensitivity. The results of a comparative study show that there is a fundamental similarity between the ion mechanisms of cellular mechanotransduction in normal and transformed fibroblasts. The quantitative differences, first of all, concern the level of functional activity of mechanosensitive channels that provide the development of the local calcium signal in the near-membrane cell region.