抄録
1. The effects of electrotonic currents on afferent nerve fibers isolated from the frog sartorius muscles were examined.
2. The spontaneous discharges were facilitated by catelectrotonus, and depressed by anelectrotonus. The frequency and adaptation of the facilitated discharges during catelectrotonus were lower and slower when a particular current was applied in the vicinity of the capsule than when applied to an axonal portion distant from the capsule.
3. Current-frequency relation curves obtained with different resting muscle lengths were always in parallel with those obtained in situ length, with certain difference of the frequency caused by the change in the muscle length.
4. The static component in discharges during stretch of the muscle at 7 mm/ sec from an initial length was also increased with catelectrotonic and decreased with anelectrotonic currents respectively, but the peak frequency in discharge at completion of the muscle stretch appeared independent of the amount of electrotonic currents applied. Consequently the dynamic component was de creased under catelectrotonus and increased under anelectrotonus.
5. After the axon was crushed at a portion close to the capsule, all the spontaneous conducting discharges were abolished, and a single or few con ducting spikes could be elicited by the electrotonic currents.
6. The discharge of abortive spikes was increased or decreased by catelectro tonic or anelectrotonic currents of about ten times greater intensity than that for affecting the propagated spike.
7. The above results suggest that the axonal portion distal to the ramifying node possesses an ability for producing long-lasting discharges, and that the ability is due to a slow adaptation of the sensory terminal membrane which differs from that of the stem axon.
