[Effect of hormonal and neurotrophic factors on the expression of fast myosin in slow muscle].

Myosin ATPase and succinic dehydrogenase activity and fast myosin (indirect immunochemical test) were assayed in m. soleus of guinea-pigs after the administration of T4 (200 micrograms/kg) to animals every day for 3 weeks. This was followed by the application of 10 mM colchicine solution to sciatic nerve for 6 min.

[Effect of trivalent iron on denervated skeletal muscles].

The activity of succinic dehydrogenase, myosin ATPase, as well as lactic dehydrogenase (LDG) spectrum and cross-section area of different type of muscle fibers have been studied for 3 weeks after denervation (control) and after denervation and intraperitoneal injection of 10(-6) M FeCl3. Intraperitoneal injection of FeCl3 prevented the development of denervation phenomena (increase in cross-section area of muscle fibers, changes in LDG spectrum).

[Lactate dehydrogenase isoenzyme activity of a fragment of the soleus muscle transplanted into the anterior chamber of the eye].

The equal relative content of LDH H and M subunits has been detected in the soleus muscle of the rat anterior eye chamber. M subunit prevalence over H subunit was revealed after transplantation of the muscle with a spinal cord segment. It is suggested that nervous system controls differential expression of LDH subunits.

[Effect of thyroidectomy on the histochemical and electrophysiological properties of the soleus muscle in rats].

In the musculus soleus of mature male rats, 6 weeks after thyroidectomy, muscle fibers with a low adenosin triphosphatase activity of myosin decrease in number, as well as the cross section area of the muscle fibers with a moderate and high activity of the enzyme. Optic density of the muscle fibers staining also decreases when succinatedehydrogenase activity is determined histochemically. There is no change in the rest membrane potential and in the character of the muscle fiber membrane sensitivity to acetylcholine.

[Effect of thyroxine on the phenotype of intact and denervated skeletal muscles in the guinea pig].

Denervation of the guinea-pig fast (m. plantaris) and slow (m. soleus) muscles, administration of alpha-thyroxine (T4) to animals followed by denervation and T4 injection entail changes in the relative content of different types of muscle fibers.