Many animal and plant cells are exposed to environmental salinity changes which cause alterations in the normal volumes of these cells. These changes, if they remained uncorrected, would disturb or even destroy normal cell function. Therefore, cells have evolved mechanisms by which they can adjust their volumes following these disturbances. During the past decade we have been investigating the mechanisms of volume regulation in one type of cell. We found that the red blood cell (RBC) of the salinity-tolerant little skate is a good model in which to study cell volume regulation. During the upcoming grant period we plan to determine how transport proteins in the cell's membrane operate to reduce cell volume after volume expansion in a dilute medium. This will involve identifying the specific membrane proteins involved in the process and the "signaling" mechanisms that "tell" the proteins that cell volume is too large, thereby activating these proteins. The results obtained in this study will be important to our understanding of the basic principles of cell volume regulation. In addition they will assist in discovering the causes of disturbances, as well as development of new treatments for diseases affecting the body's ability to maintain normal cell volume.
