A simple method for beveling micropipettes for intracellular recording and current injection.

A simple equipment for beveling intracellular microelectrodes has been made by modifying a conventional turntable. An agar disc containing ceric oxide polishing compound which was put on a flat glass disc was found to be suitable for beveling of Pyrex single- and double-barreled micropipette electrodes with a tip diameter larger than 0.1 mum. Although the beveled microelectrodes have not always been shown to give better cell penetration into the frog retinal rods than unbeveled find ones, better records could usually be obtained when electric currents were injected into cells, probably being due to their lower resistance, noise, tip potentials and coupling resistance between two barrels.