Stimulation and Recording

The nerve is stimulated electrically from an isolated stimulator. The voltage, stimulus duration and stimulus frequency may be controlled and there is a facility to deliver either single or paired stimuli. It is also possible to directly stimulate the muscle. For most experiments the stimulus voltage will be in the range 0-10 V, the duration will be 50 µsec and the frequency of stimulation 0.1 Hz. Isolated muscle fatigues rapidly if stimulated at high frequencies for extended periods.

Records of compound nerve action potentials are obtained from the recording electrodes on the nerve. The records are amplified (AC amplifier) and displayed on an oscilloscope.

Contractile tension is measured isometrically using a strain gauge transducer which converts a tension change into a voltage. The strain gauge output is amplified (DC amplifier) and displayed on the second channel of the oscilloscope. By calibrating the strain gauge it is a simple matter to convert the display voltage to a tension change and express the tension in g.