ABSTRACT
This chapter discusses the concepts of cell volume regulation from a clinical perspective. As clinicians, the understanding of cell volume regulatory physiology adds insight to patient care on a variety of levels. The most obvious of these lies in the area of total body osmotic homeostasis. Plasma hypotonicity, usually with hyponatremia, is seen clinically more frequently than plasma hypertonicity. Hyponatremia in the setting of low circulating blood volume is observed in malnutrition, congestive heart failure, nephrotic syndrome, and hepatic cirrhosis. In contrast, chronic changes in plasma tonicity are accompanied by longer-term adaptive mechanisms which substantially complicate therapy. While acute changes in tonicity and resultant cell volume are buffered primarily by rapid transport of electrolytes, chronic hypertonic stress evokes mechanisms that involve the slow accumulation of organic solutes. The toxic changes seen with glutamate in vitro are biphasic and involve initial, acute swelling of neuronal dendrites and cell bodies followed by a more slowly evolving neuronal degeneration.
