The McGill Physiology Virtual Lab

RMP Laboratory

RMP >  Procedure
  Because the experiment relies on the integrity of the muscle membrane, great care should be exerted during the dissection.

The abdomen of the crayfish is dissected out. The dorsal extensor muscles are used in this experiment.

Cut along the abdomen (tail) on each side and on top; using forceps, tear the upper part of the abdomen from the much larger and lower musculature. The dorsal extensor muscles separate readily from the larger ventral mass of flexor muscles. Although both ventral and dorsal parts can be used, it is preferable to keep the upper part of the abdomen to record potentials.
A glass microelectrode is selected, taking special care not to touch the tip. (These microelectrodes are made from capillary tubes heated in the middle and pulled mechanically to a fine tip. They are then filled with 3 M KCl.)


The glass microelectrode is placed in the holder of the micromanipulator. An Ag/AgCl wire is inserted into the microelectrode. A reference Ag/AgCl electrode is placed directly into the Ringer's solution in the bath. Both electrodes are connected to the amplifier.
Pin the dorsal part of the tail up: recordings will be made with the superficial extensor muscles.
As the experiment will be performed using bath solutions with different concentrations, it will be necessary to aspirate an old solution out of the chamber with a syringe, in preparation for a new bath solution.
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