Use of Ion-Selective Microelectrodes and Fluorescent Probes to Measure Cell Volume

Neurons are particularly vulnerable to changes in intracellular and extracellular solute composition under both physiological and pathological conditions. This is a consequence of their small volume/surface ratio in conjunction with their incessant synaptic and action potential activity and the paucity of the extracellular space of the central nervous system. In spite of their physiological, clinical, and therapeutic implications, little is known about the cellular and molecular mechanisms with which nerve cells maintain their water volume within narrow limits in the face of the Donnan effect and substantial net solute and water fluxes across their plasma membranes. Changes in brain volume resulting from the failure of cellular osmoregulatory mechanisms can lead to permanent neurological injury and death. Neuronal and glial cell swelling (cytotoxic edema), a dreaded complication of ischemia, trauma, seizures, or metabolic disorders, is believed to be the result of a loss of control of cell volume. Hence, it is important to develop appropriate methods to study cell volume.