Myocardial damage in thyrotoxicosis--ultrastructural studies.

Lack of uniform views concerning subcellular image and possible meaning of free radicals in the myocardial damage prompted us to study rat hearts submitted for chronic thyrotoxicosis. The studies were performed on 30 Wistar white rats. The material was obtained from anterior wall of the left ventricle of the heart. To confirm the role of free radicals one group of rats was given ascorbic acid, a well-known substance with anti-oxidation properties (free radical scavenger). In the control group we observed a typical structure of the myocardium. In the group with thyrotoxicosis a great degree of subcellular structural damage was noticed. These alterations correspond to nonspecific myocardial damage that can be meet in hypoxia, reperfusion or in toxic myocardial damage. However, in case of vitamin application generally known to have anti-oxidation properties, damages were significantly less intensive and occurred more rarely. It seems to indicate a significant role of free radicals in the generation of these alterations.