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 electrophysiologi cal measurements, particularly when using the patch-clamp technique. T he ionic conductivities and mobilities of certain less common organic ions were measured for use in junction potential corrections in electr ophysiological 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 pote ntials were directly measured for a number of typical simplified patch -clamp solutions containing these ions. The measured junction potentia ls generally agreed well with the values calculated using the Generali zed Henderson Equation with the appropriate ionic mobility. The accura cy of the measurements is discussed.