Sodium-sensitive glass microelectrode: modified Thomas recessed-tip configuration.

Using a glass-membrane, sodium-sensitive microelectrode, a modified Thomas sodium-sensitive electrode has been developed. The modified Thomas electrode possesses a high sensitivity (57.9 mV/log aNa), a high selectivity (KpotNa,K less than 0.005), a relatively low electrical resistance (7.65 X 10(11) ohms), a small sensing chamber (10 microns3), and can be made in the double-barreled configuration. The modified Thomas electrode is designed to directly measure the intracellular sodium concentration of epithelial cells.