TRPM4 is a Ca 2+-activated but Ca 2+-impermeable cation channel. An increase of [Ca 2+] i
induces activation and subsequent reduction of currents through TRPM4 channels. This
inactivation is strikingly decreased in cell-free patches. In whole cell and cell-free
configuration, currents through TRPM4 deactivate rapidly at negative potentials. At positive
potentials, currents are much larger and activate slowly. This voltage-dependent behavior
induces a striking outward rectification of the steady state currents. The instantaneous …