The IP3-Dependent Signaling Pathway Is Involved in the Regulation of Atrophic Processes in Skeletal Muscles during Their Unloading

The hypothesis of the relationship between changes in the calcium throughput of dihydropyridine receptors (DHPR) and the accumulation of ATP and phosphoinositide 3-kinases (PI3) in the muscle during its unloading was checked. We also checked the PI3K signaling pathway involvement in the atrophic process regulation in skeletal muscles during their unloading. To do this, we inhibited DHPR and PI3K with nifedipine and with LY294002. We found that both sarcolemma-related units are involved in the regulation of ATP content, calcium signaling markers, and IP3 levels in the unloaded m. soleus. DHPR inhibition prevents ATP, Ca2+, and IP3 accumulation in soleus under unloading. PI3K inhibition reduces the degree of atrophy, ATP and IP3 content in muscle, and regulates the Ca-dependent signaling markers under tree day soleus unloading.