The measurement of ionic conductivities and mobilities of certain less common organic ions needed for junction potential corrections in electrophysiology

Junction potential corrections are often required in electrophysiological measurements, particularly when using the patch-clamp technique. The ionic conductivities and mobilities of certain less common organic ions were measured for use in junction potential corrections in electrophysiological measurements. The mobilities of these ions relative to K+ were: aspartate (0.30), choline (0.51), gluconate (0.33), glutamate (0.26), HEPES (0.30), isethionate (0.52), MES (0.37), MOPS (0.35), N-methyl-d-glucamine (0.33), and Tris (0.40). In addition, junction potentials were directly measured for a number of typical simplified patch-clamp solutions containing these ions. The measured junction potentials generally agreed well with the values calculated using the Generalized Henderson Equation with the appropriate ionic mobility. The accuracy of the measurements is discussed.