| Abstract: | Experiments on frogs (Rana ridibunda) showed that, unlike in the whole nerve, prolonged after-depolarization and the associated phase of summation are absent in the single node of Ranvier of isolated nerve fibers. If, however, special measures are taken to prevent the stretching of the Ranvier node of single fibers, prolonged after-depolarization can be found in them. It is concluded that the absence of prolonged after-depolarization in single Ranvier nodes of nerve fibers isolated without additional precautions is the result of injury to the excitable membrane or to disturbance of the integrity of the ionic barrier surrounding it as a result of stretching of the fibers during dissection. |
