Tetraphenylborate-sensitive electrode for measuring membrane potential.

The paper describes the construction of a new type of ion-selective electrode sensitive to tetraphenylborate (TPB-) and its electric characteristics. The electrode responds to increasing concentrations of the TPB- anion in accordance with the Nernst equation and can be used down to 0.1 microM concentration. The applicability of the electrode for measuring the membrane potential (positive inside) was proved in inside-out oriented membrane vesicles derived from Paracoccus denitrificans. The calculated values were 175 +/- 12 mV with NADH and 180 +/- 6 mV with succinate.