[Distribution of calcium ions in the muscle fibers of the rat diaphragm depending upon their state and the method of histochemical treatment].

Distribution of calcium ions in the rat diaphragm muscle fibers has been studied electron histochemically using various fixation techniques and chemical treatment of the tissue. When potassium pyroantimonate in water solution is used after a short perfusate fixation with aldehydes, the reaction product granules are revealed in mitochondria, in the disk I, in the center of the disk A, more seldom the precipitate is found in the sarcoplasmic reticulum (SR) and in the T-system. The presence of calcium ions in the precipitate is proved by means of treatment the preparations with ethylenglycol- and ethylen-diamine-tetra-acetic acids. When contracture is resulted from potassium rhodanide administration, in mitochondria the reaction product granules decrease in their number, the precipitate disappears from the central part of the disk A, while the number of the granules increases in the SR terminal cisterns. The data obtained are compared with calcium ions distribution observed at the freezing-substitution method without an additional chemical fixation, as well as the histochemical fixations after Oschman method and at a usual fixation with OsO4. Certain similarity is revealed in distribution of the calcium pyroantimonate granules at aldehyde fixation and when the freezing-substitution method is used.