Figure 1.

Effects of the PLC blocker U73122 and PIP₂ on whole-cell currents through TRPM4. (A) Time course of the whole-cell currents after activation by 3 μM Ca²⁺ via the patch pipette. Shown are the currents obtained from voltage ramps at −100 (triangles) and +100 mV (circles), respectively. The IV curves at the right side panel are from the currents indicated by solid circles. Arrows mark the onset of the whole-cell mode. (B) Same experiment as in (A), but now in the presence of 10 μM U73122. Note the complete absence of desensitization and the nearly linear IV curves (right-side panel, current points are marked at the time course). (C) Same experiment as in (A). After desensitization, U73122 was applied to the bath. Note the slow recovery of the current traces (IV curves from ramps as in (A). (D) Whole-cell configuration was established with 3 μM Ca²⁺ and 10 μM diC8-PIP₂ in the pipette. After initial desensitization, the currents completely recovered (traces as the right-hand side from the indicated points).