Effects of thyroidectomy on biochemical and ultrastructural aspects of rat slow and fast muscles

Thyroidectomy provoked the reduction of the oxygen consumption rate in state 3 respiration in both Extensor Digitorum Longus (EDL, fast twitch) and Soleus (slow twitch) muscles of rat, being the last one the most affected. Morphological alterations after 8 weeks of thyroidectomy were found in mitochondria. These organelles exhibited cristae swelling and formation of autophagic vacuoles in subsarcolemmal and intermyofibrillar spaces. Altered mitochondria were also seen in the axon terminal and the postjunctional region of motor end-plate