ABSTRACT
Mechanosensitive or stretch-activated (SA) channels respond to membrane stress by changes in open probability. These channels exist in auditory cells, stretch receptors, muscle spindles, vascular endothelium, and other neurosensory tissues where their physiological function seems readily apparent. A reliable feedback system for short-term volume regulation ultimately requires some type of mechanical sensor to convey information about cell size. The significant calcium permeability of the SA-cat channel raised the possibility that Ca might function as a second messenger for translating mechanical stress into regulation of ion transport. In rabbit cortical collecting tubule cultures, hypotonic solutions also increase activity of a maxi-K channel at the apical membrane of principal cells. In addition to the large SA-cat family of mechanosensitive channels, there are smaller families of mechanosensitive channels that are not as widely distributed among different species but are more highly selective for particular ions.
