ABSTRACT
Cell-volume homeostasis describes the general ability of most cells to maintain a rela tively constant volume, even in the face of significant changes in the osmolarity of the extracellular fluid. An exception are mammalian nonnucleated erythrocytes, which over a considerable range of imposed osmolarities (from approximately 2 2 0 to 380 mosM) behave as perfect osmometers, their volume changing inversely with extracel lular osmolarity. The present chapter discusses the critical part played by the plasma membrane in cells other than mammalian erythrocytes in the maintenance of steady cell volumes. The important role of membranes in volume control is seen clearly in the association of functional membrane lesions with cell swelling. Occurrence of cell swelling in poisoned or anoxic tissues is, of course, well known.
