EFFECT OF IMPALEMENT WITH A MICROPIPETTE ON THE LOCAL CELL MEMBRANE. STUDY BY SIMULTANEOUS INTRA-AND EXTRACELLULAR RECORDING FROM THE MUSCLE FIBER AND GIANT AXON

Abstract

By means of a coaxial pencil-type microelectrode, simultaneous intra- and extracellular re-cording was made of the action potential of the toad''s sartorius muscle fiber and the crayfish giant axon. Stimulation was made at a point some 3 mm distance from the site of recording. Depending on the preparation used and also on the time for which the membrane has been impaled, the configuration of the extrap was various, even when the intrap was about normal; from configurations more like the intrap itself to those similar to its second derivative, with configurations resembling the first derivative of the intrap in between. In recordings immediately after the membrane was impaled, the extrap of the muscle fiber resembled most frequently the first derivative of the intrap, while that of the giant axon was usually triphasic and similar to the second derivative of the intrap. The state of the local membrane corresponding to each configuration of the extrap was discussed. The "efflux mechanism" in the membrane appeared to be more susceptible to impalement than the "influx mechanism".