title: A simple circuit for automatic continuous recording of microelectrode resitance.
abstract: Microelectrodes with tip diameters less than or equal to 0.5 micron used for intracellular recording sometimes give artefactual readings due to tip potentials. These appear to be caused by a change in the tip of the microelectrode upon impalement with a corresponding change in microelectrode resistance. A circuit is described which enables the resistance of the microelectrode to be continuously monitored throughout an experiment. The electrode is used as one half of a potential divider for an a.c. signal at 20 Hz with an amplitude of 20 mV. The other half of the potential divider is a 1000 Momega resistor. The a.c. signal across the microelectrode is approximately proportional to the microelectrode resistance in the range 0 --50 Momega. This signal is amplified, rectified and smoothed and then displayed on a chart recorder or other convenient meter.
mesh_terms: D000818:Animals; D004553:Electric Conductivity; D004594:Electrophysiology / Q000295:instrumentation*; D066298:In Vitro Techniques; D008722:Methods; D008839:Microelectrodes; D009132:Muscles / Q000502:physiology; D011817:Rabbits