caa a22 4500 606162771 CHVBK 20210128100640.0 cr unu---uuuuu 210128e20150201xx s 000 0 eng 10.1007/s11062-015-9497-y doi (NATIONALLICENCE)springer-10.1007/s11062-015-9497-y Frequency Dependence of Parameters of the М Response of the Rat M. Tibialis in the Norm and in Experimental Hyperthyroidism and Hypercorticoidism [Elektronische Daten] [V. Sobolev, V. Trush, K. Litvyak, I. Morozova] In experiments on rats, we studied the effects of experimental hyperthyroidism (subcutaneous injections of L-thyroxine, 50 μg/kg·day during 7 days) and hypercorticoidism (daily i.p. injections of hydrocortisone, 3 mg/kg·day during 30 days) on parameters of the М responses of the m. tibialis anterior after stimulation of the n. peroneus by single stimuli and their series with the instant frequency increasing linearly from 4 to 74 sec−1. In hypercorticoidism, the latency of single М responses was, on average, 30% longer, while the amplitude was 29% lower than those in the control. Multicomponent М potentials were observed in this group more frequently (in 37.5% of the cases); the duration of these responses demonstrated no significant changes. Hyperthyroidism caused shortening of the latency of the М responses (by 15%) and a decrease in their duration (by 25%). The mean amplitude of the responses exceeded the control by 70%; significant modifications of their shape were not observed. Experimental hyperthyroidism and hypercorticoidism were accompanied by a more expressed decrease, as compared with the control, in the amplitude with increase in the frequency of stimulation of the nerve and decreased stability of generation of the responses. The frequency level at which the inverse dependence between the М response amplitude and stimulation frequency began to be clearly pronounced decreased in animals with the modified hormonal status. Probable reasons for peculiarities of the frequency dependence of the parameters of the М responses in hyperthyroidism and hypercorticoidism are discussed. Springer Science+Business Media New York, 2015 hyperthyroidism nationallicence hypercorticoidism nationallicence thyroxine nationallicence hydrocortisone nationallicence skeletal muscle nationallicence M response nationallicence neuromuscular transmission nationallicence Sobolev V. Donetsk National University, Donetsk, Ukraine aut Trush V. Donetsk National University, Donetsk, Ukraine aut Litvyak K. Donetsk National University, Donetsk, Ukraine aut Morozova I. Donetsk National University, Donetsk, Ukraine aut Neurophysiology Springer US; http://www.springer-ny.com 47/1(2015-02-01), 53-60 0090-2977 47:1<53 2015 47 11062 https://doi.org/10.1007/s11062-015-9497-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11062-015-9497-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sobolev V. Donetsk National University, Donetsk, Ukraine aut NATIONALLICENCE 700 1- Trush V. Donetsk National University, Donetsk, Ukraine aut NATIONALLICENCE 700 1- Litvyak K. Donetsk National University, Donetsk, Ukraine aut NATIONALLICENCE 700 1- Morozova I. Donetsk National University, Donetsk, Ukraine aut NATIONALLICENCE 773 0- Neurophysiology Springer US; http://www.springer-ny.com 47/1(2015-02-01), 53-60 0090-2977 47:1<53 2015 47 11062