Quantitative Study of Stretch Channel Activation.

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In these years, stretch activated (SA) channels have been found in most cells. Though we know little about the physiological functions of this type of channel, their ubiquitous distribution suggests that they have fundamental roles in cells. To investigate the gating mechanism of SA channels we have to measure membrane tension, which has not been done yet. According to Laplace's law the membrane tension is determined by transmembrane pressure and the curvature of the patch. The aim of this research project was to visualize the patch and to make simultaneous measurements of the patch shape and SA channel activity during pressure change. The obtained results are as follows :1, We could visualize patch membranes with a resolution of 15 um/pixel.2, The curvature of the patch was changeable depending on pipette pressure.3, The patch membranes followed Hook's law extended to two dimension and the elastic constant of typical patches was 50 dyn/cm.4, The SA channel activity was well correlated with tension but not pressure.5, It was found that the patch thickness did not change during tension change suggesting that the tension bearing element was cytoskeleton attached to SA channel proteins, but not lipids.