[Paradoxical reactions of a neuromuscular preparation (on the 100th anniversary of their discovery by N.E. Vvedenskii)].

The discovery of the intensity of repetitive stimulation pessimum and of the paradoxical response to stregthening of stimuli in a parabiotic nerve, is presented in historical aspect. Both phenomena are shown to be based on the mutual electrical delay in propagated APs when the number of synchronously activated nerve fibers is increased. The delay may cause a propagation block through these nerve regions where the safety factor is diminished.