[Paradoxical effects of powerful electric stimuli].

Variants of mechanism of the response paradoxical weakening at the stimuli increase in conditions of parabiosis and pessimum of the neuro-muscular preparation, are regarded. The possibility of "long-distance" kat-electrotonic blocking of nervous impulse at the increase of stimulating current pulses, was studied. The kat-electroton was shown to spread in the frog n. ischiadicus, even with short current pulses, for 30--40 mm. Even in single nervous fibers (crayfish) as well as in the frog n. ischiadicus, when increasing the rare stimuli beyond the strength limits (50 thresholds), the reversible reducing of action potential (AP) recorded at a not too long distance from the stimulating electrodes (catode depression), takes place. Near the transversal cut of the nerve (i.e. in the parabiotic area) the effect is increased. In conditision of frequent stimulation, the long-distance electrotonic depression of AP is more clear than with rare stimuli.