Abstract:
The main goal of the research was to estimate the morpho-functional condition of the neuromotor apparatus of the rat soleus muscle under simulated gravitational unloading, as well as under simulated gravitational unloading combined with the action of axial load and support reaction force. Model experiments were performed on male laboratory rats weighing 190-210 g in strict accordance with the accepted bioethical standards. Gravitational unloading was simulated by the antiorthostatic hanging method. Within 7 and 35 days. For the action of the support load, the animals were placed daily on a hard horizontal surface for 90 minutes. The H-reflex and the M-wave of the soleus muscle were recorded; the threshold, maximum amplitude, latency and duration of the evoked potentials were determined. Muscle wet and dry weights were also evaluated. We found that during simulated gravitational unloading occurs an increase in the reflex activity of the m. soleus motoneurons, reduces the reliability of neuromuscular transmission, and initiates atrophic processes. Periodic application of a support load under conditions of short-term (but not long-term) simulated hypogravity prevents alteration in the central and peripheral parts of the neuromuscular apparatus of the rat soleus muscle.
