[Effects of nifedipine on the mechanical properties of sarcolemma and modulation of calcium accumulation dynamics in fibers of the rat soleus muscle under short-term hypogravity conditions].

It has been shown that the modulation of the mechanical properties of sarcolemma by nifedipine may be related to the dynamics of accumulation of calcium ions under short-term rat hindlimb suspension. The basal calcium level was measured by the fluorescence probe Fluo-4AM, the transversal stiffness of different parts of the contractile apparatus and sarcolemma was estimated by atomic force microscopy, and the content of desmin was determined by gel electrophoresis with immunoblotting. It has been found that nifedipine has a protecting effect on muscle fibers under hypogravity by decreasing the degradation of desmin and proteins that determine the transversal stiffness of sarcolemma and the contractile apparatus, and the intensity of the increase in the basal calcium level. It was shown that the selective blocking of L-channels leads to an increase in the basal calcium level in intact soleus fibers. At the same time, the transversal stiffness of sarcolemma and the contractile apparatus increased. The mechanism of this increase is still unclear; however, it is assumed that it mediates the protecting action of nifedipine.