TRPM4 is a Ca(2+)-activated nonselective cation channel. The channel is activated
by an increase of intracellular Ca(2+) and is regulated by several factors including
temperature and Pi(4,5)P2. TRPM4 allows Na(+) entry into the cell upon activation,
but is completely impermeable to Ca(2+). Unlike TRPM5, its closest relative in the
transient receptor potential family, TRPM4 proteins are widely expressed in the body.
Currents with properties that are reminiscent of TRPM4 have been described in a variety
of tissues since the advent of the patch clamp technology, but their physiological
role is only beginning to be clarified with the increasing characterization of knockout
mouse models for TRPM4. Furthermore, mutations in the TRPM4 gene have been associated
with cardiac conduction disorders in human patients. This review aims to overview
the currently available data on the functional properties of TRPM4 and the current
understanding of its physiological role in healthy and diseased tissue.
