ABSTRACT
The high water permeability of most cell membranes ensures that these osmotic responses are generally quite rapid. In “anisosmotic volume regulation” studies, the subsequent responses of the cell following the acute gain or loss of water are studied. Among the numerous biochemical and biophysical processes and mediators that have been proposed to serve as transduction mechanisms to couple alterations in cell volume with activation of volume-regulatory solute transport processes, perhaps none has been invoked more frequently than calcium. The most widely used approach for studying cellular volume regulation has been the acute imposition of an osmotic stress on a tissue or cells. This protocol generally involves the rapid addition or deletion of osmotically active solutes from the medium bathing the cells. The activities of various plasma membrane solute influx and efflux pathways can be modulated by a wide variety of physiological mechanisms under isosmotic conditions.
