Changes in the Duration of the Electric Response of Single Nerve Fibers Following Repetitive Stimulation

Abstract

Single nerve fibers were isolated from the nerve innervating the sartorius or semitendinosus muscle of the toad (Bufo marinus). Single nerve fiber responses were recorded with three arrangements of the "bridge insulator" method. During stimulation at 50 to 150 pulses per second for 20 to 140 minutes the spike duration was progressively increased. After tetanization the spike duration usually continued to increase at a more rapid rate. Within 5 to 60 minutes further prolongation stopped and within 1 to 10 hours the spike duration was normal. The duration of the response of tetanized fibers was from 2.5 to more than 10 times the spike duration of untetanized fibers. Prolongation was observed in nerve fibers isolated from nerves tetanized in vivo.

Thresholds and Plateaus in the Hodgkin-Huxley Nerve Equations

“…This synthetic process, carried out with the aid of the analog computer, leads to a better understanding of the complete system than can be obtained by considering all the variables at once, and suggests how modifications in the separate equations will affect the behavior of the complete system. In particular, it becomes obvious how plateau-type action potentials can be produced, resembling those obtained experimentally from heart (Weidmann (1957)), frog node (Spyropoulos (1956)), frog muscle (Falk and McGrath (1958)), and squid axon (Tasaki and Hagiwara (1957)). …”

Electrophysiology of Supramedullary Neurons in Spheroides maculatus

“…13), appear difficult to reconcile with the Hodgkin-Huxley theory (36). Prolongation after repetitive activation has also been observed in the node of Ranvier (47), and in Aplysia (53). In the former case, prolonged tetanization is necessary, but in the latter the situation is similar to that in the puffer.…”

Effects of calcium and magnesium on the frequency of miniature end‐plate potentials during prolonged tetanization

“…frequency, then the effects of Mg on this frequency might arise secondarily from an effect of Mg on the quantity of Na that entered the nerve terminal during a tetanus. For instance, Mg may have effects similar to Na and other divalent cations and prolong the action potential in the nerve terminal during a tetanus, thereby increasing the quantity of Na that enters with each impulse (Spyropoulos, 1956;Spyropoulos & Brady, 1959;Connelly, 1962). Our results may be compatible with any or all of these ideas, and we cannot decide among them in any conclusive manner.…”