[Characteristics of mitochondria and myocardium ultrastructure of rats following chronic incorporation of cesium radionuclides 137 Cs]. / Kharakteristika mitokhondrii i ul'trastruktura miokarda krys v usloviiakh prodolzhitel'noi inkorporatsii radionuklidov 137 Cs.

Ultrastructure, tissue respiration and oxidative phosphorilation were studies in the myocardium of animals after chronic natural irradiation by 137Cs in quantities that can in reality threaten population of radionuclide-polluted regions. Decline in the respiratory activity of the myocardium and ultrastructural disorders can be attributed to the effects of ions of radioactive Cs which is also a potassium antagonist. A hypothesis has been put forward according to which cesium blocks potassium channels in mitochondria and thus changes the volume and configuration of internal mitochondrial membranes, and impacts the respiratory processes. In the opinion of the authors, these changes characterize the mitochondrial phase of apoptosis which, in the event of chronic exposure to radionuclides, is a compensatory-adaptive mechanism eliminating the least immutable subpopulation of cardiomyocites.

[Mitochondrial oxidation and ultrastructure of the myocardium on a background of incorporation of cesium radionuclides]. / Mitokhondrial'noe okislenie i ul'trastruktura miokarda pri inkorporatsii radionuklidov tseziia.

Parameters of the mitochondrial oxidation and ultrastructure of the myocardium in white rats were studied on a background of consumption of food supplemented with 137Cs at 60 or 600 Bq/kg (calculated doses were 1.5 and 15 microGy, respectively). The observed stimulation of the respiratory activity in myocardial samples cultivated on endogenous and several exogenous substrates was found to reduce the effectiveness of energy production by dissociation of oxidative phosphorylation and disruption of macroerg deposition in the form of creatine phosphate. Ultrastructural findings included swelling of mitochondria, matrix clarification, partial reduction of the number of crists, and myeline-like bodies in the matrix. Observed were high nucleus structural polymorphism with extension of the perinuclear space, spotted distribution of chromatin, and modification of the myofibril structure. These morphofunctional changes can be considered as reflection of apoptosis associated with activation of peroxidation.