Figure 1. Hypoosmotic-induced membrane stretch activates TRPC5 channel.

Pseudocolour images of GFP-TRPC5-transfected cells showing GFP-fluorescence (A) and ratiometric [Ca²⁺]_i responses to control (B) and 210 mosmol kg⁻¹ (C) solutions. Changes in [Ca²⁺]_i are reflected by the ratio of fura-2 emission at 340 to 380 nm excitation wavelength (see colour bar). Scale bar, 50 μm. D, time course of the calcium changes during hypoosmotic solution exposure in cells transfected with TRPC5 and in non-transfected cells (E) in the same field. Image C corresponds to the time course of calcium increase indicated by the arrow in D. For each experiment, 50–75 cells in the field were selected at random and identified as GFP(+) and GFP(–). F, percentage of cell responding to 210 mosmol kg⁻¹ solution exposure in cells expressing TRPC5 under the indicated experimental condition (***P < 0.001, Z-test; each condition in > 3 independent experiments). The * denotes statistical significance between cells transfected with TRPC5 in the absence of calcium, untransfected cells and cells transfected with the empty vector versus cell transfected with TRPC5 in the presence of extracellular calcium. G, bar graphs summarizing the responses of TRPC5 positive cells after incubation with 2 μm thapsigargin compared with cell incubated with 2 μm DMSO in a number of cells > 150 in six independent experiments (***P < 0.001; Z-test).