Study of contractile properties of muscles of curarized animals by the method of stimulation impedancography

: The effect of relaxation doses of tubocurarine on the stimulation and contractile properties of muscles in complete synaptic block was studied in experiments on laboratory rats by means of a previously developed method of stimulation impedancography. During intramuscular electrostimulation the stimulus threshold for short 0.01 mc test impulses increased, while the steepness of the characteristic "force of action--contractile effect" curve, registered at 1 mc impulses, reduced. The reduction was caused by loss of the function of synaptic nerve structures which take part in recruiting the contractile elements. Nonsynaptic mechanisms of recruiting through direct stimulation of the muscle fibres ensure 45% of recruitment. Changes of the duration of the contraction were not detected in the first 20 minutes of the effect. After 60-80 minutes of relaxation there was a tendency to prolongation of the time of the contraction act, which may be caused by prolonged immobilization of the animals.