Electrodes, patch-clamp recording pulling

Focal recording electrodes are pulled from glass capillary tubes (e.g., 75 il, 1.5-mm outer diameter) and then fire polished and shaped on a microforge to allow perpendicular approach to the muscle for obtaining better seal resistance. The loose-patch electrodes are made with an inner diameter of 5-10 pm. When filled with the appropriate bath solution, they have resistances of 0.5-2 M 2. Seals around the boutons are made by applying mild suction and usually increase the resistance two to six times (seal factor Rivosecchi et al. 1994). Recordings are made with a loose patch-clamp amplifier and contain a calibration pulse to measure electrode series and seal resistances. These measurements are used to correct for attenuated current amplitudes at the electrode tip. 

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