Organic osmolyte channels in cell volume regulation in vertebrates.

Volume-activated organic osmolyte channels are found in a variety of vertebrates and cell types and show both common and disparate features. Upon exposure to hypotonic conditions, organic compounds such as taurine are released through these channels, reducing the intracellular solute concentration and thereby restoring cell volume. Various structurally diverse membrane proteins have been proposed as the channel. Accumulating evidence suggests that some of these proteins may play a more significant role as regulators than as the channel itself. Intracellular ionic strength may also modulate the release of organic osmolytes through these channels.