Organic Osmolyte Channels: A Comparative View

Cells respond to osmotic swelling by releasing inorganic ions and small organic molecules (organic osmolytes). In many cell-types, osmotic swelling results in the activation of an outwardly-rectifying anion-selective current. The channel underlying this current has a significant permeability to a number of organic osmolytes and may play a role in the hypoosmotically-activated efflux of these compounds. However, there is also evidence that the volume-regulatory efflux of organic osmolytes involves other pathways which may be selective for neutral osmolytes over anions.