THE CORRECTION BY ARGININE, MODERATE PHYSICAL ACTIVITY AND THEIR COMBINATION OF SKELETAL MUSCLE CONTRACTIVE FUNCTION DISTURBANCES` FOR STEROID MYOPATHY IN EXPERIMENTS ON RATS
Authors: Trush V. , Sobolev V. , Popov M. 
Published: December 2024

The aim of the research was to study the effectiveness of the arginine (ARG, 100 mg/kg/day), moderate dynamic physical activity (FA) and their combination in compensating of impaired contractile function of m. tibialis anterior, caused by the administration of dexamethasone (DM, 0,25 mg / kg / 2 days, for 10 to 60 days), were studied in experiments on rats.
Methods. The experiments were held on young female rats (195–205 g), divided into 5 groups: control (n=10, C-group), the I-st experienced (n=30, received dexamethasone, DM-group), the II-nd experienced (n=30, received DM and daily swimming, DM+FA-group), III-rd experienced (n=30, received DM in combination with ARG, DM+ARG-group) and IV-th experienced (n=30, received DM in combination with ARG and daily swimming, DM+ARG+FA-group). Each experimental group was divided into 3 groups (n=10 in each) depending on the duration of the experimental exposure (10, 30 and 60 days).
Dexamethasone (KRKA, Slovenia) was administered at a dose of 0,25 mg/kg, once in 2 days, intraperitoneally, arginine («Cardioarginine», «Zdorovye», Ukraine) – daily, subcutaneously, at a dose of 100 mg/kg. Animals of DM+FA- and DM+ARG+FA-groups began to be subjected to physical activity from the 1-st day of medications administration, daily until the end of their administration periods. FA was modeled by swimming at a comfortable temperature (37 ± 1°C) at an arbitrary speed without additional weights, gradually increasing its duration from 5 to 60 minutes per day.
On anesthetized animals (sodium thiopental, 100 mg/kg), the parameters of the functional state of m. tibialis anterior under different modes of its contractions, using myography and ergography were studied during stimulation of the peroneal nerve with superthreshold electric current.
Results. ARG, FA and their combination, used with DM, prevented the deterioration of skeletal muscle (SM) resistance to fatigue, which is characteristic for DM-groups, and even led to an elongation (p<0.05 relative to control) of maximum (all these factors) and submaximal (arginine or its combination with swimming) periods of SM performance at certain stages of experimental exposure.
The use of the arginine, moderate FA and their combination, used with DM, had an ambiguous effect on the contractile parameters of the SM. ARG completely compensated the deterioration of the parameters of single and tetanic SM contractions caused by DM. In case of DM`s use in combination with FA, the change in the contractile parameters of the SM in the dynamics of the 2-month period of experimental exposure was of a phase nature: at the initial stages (10 days after) they worsened, while at the end of the 2-month period, they were normalized and the absolute force of tetanic contraction was even increased (p<0,05 relative to control). ARG, used in combination with FA and DM, prevented the deterioration in muscle contractile parameters typical for DM+FA-groups after the first 10–30 days of exposure, and at the end of the 60-day period of exposure, it led to an improvement of its ergometric parameters (p<0,05 relative to control).
Use in combination with DM the arginine, moderate FA and their combination, used with DM, had an ambiguous effect on the speed parameters of the SM`s contraction: ARG prevented the deterioration of the contraction`s speed parameters, while in case of DM`s use with FA or the combination «FA+ARG», their deterioration was noted.
Conclusion. ARG ensured full compensation of disorders of the SM`s contractile function caused by the DM`s administration. Moderate FA and its combination with ARG caused a deterioration of the SM contraction`s speed parameters on the background of an initial deterioration of its single and tetanic contractions` parameters among animals of the DM+FA-group. The results obtained cast doubt on the effectiveness of moderate aerobic physical activity to maintain fast muscles` normal functional parameters during glucocorticoid therapy. At the same time, in case of FA`s use in combination with glucocorticoid therapy, it is advisable to additionally administrate moderate pharmacological doses of the ariginine for better tolerability of skeletal muscles to FA.