[AMPLITUDE-FREQUENCY'S DEPENDENCE OF M-RESPONSE OF THE SKELETAL MUSCLE OF RATS WITH EXPERIMENTAL HYPERCORTICOIDIZM]

In experiments over the mature white female rats the influence of the hypercorticoidizm (simulated by daily parenteral injection of hydrocortisone in a dose of 3 mg/kg/days for 30 days) on some parameters of the M-response of the forward tibial muscle with a different frequency of stimulation of the low-tibial nerve is studied. It is established that the hypercorticoidizm is followed by lengthening of the chronaxia of the forward tibial muscle at its indirect irritation (by 69 per cent), deterioration of stability of M-response's generation, lengthening of the latent period (by 30 per cent) and to reduction of amplitude (by 29 per cent) of single M-responses against increase in frequency of polyphase potentials (to 35 per cent). At animals with hypercorticoidizm in the range of low frequencies of nerve's stimulation (10-30 imp/s) periodic generation of higher-amplitude M-responses, than at control, against their low initial amplitude was observed, which can testify in a favor of an initial partial blocking of synapses. The hypercorticoidizm was followed more expressed, in comparison with control, decreasing of M-responses' amplitude in the process of increasing in frequency of low-tibial nerve's stimulation, decreasing in frequency of nerve's stimulation on achievement which inverse relationship between M-responses' amplitude and frequency of nerve's irritation was established.