Cell contamination due to the use of carrier-based microelectrodes.

When using microelectrodes for intracellular ion activity studies, some uncertainties such as interference from cytosolic components at the microelectrode, cell damage, and cell contamination may arise. A model, which treats kinetic processes of the loss of carriers from the membrane phase of microelectrodes into the cytosol and cell membrane, is used for an estimation of the extent and time course of contamination by impaled ion-selective microelectrodes. An isolated model cell consisting of a plasma membrane surrounding a cytosolic milieu is assumed. The results of its considerations represent a worst case situation, in which significant contamination of the cell membrane of such a small isolated single cell might occur during time periods of electrophysiological experiments. In more complex situations, such as in intact tissues, the equilibrium membrane concentrations may be substantially less.