[Ultrastructural changes in the muscle fibers of the rat diaphragm and the dynamics of intracellular calcium redistribution as affected by an anticholinesterase substance--chlorophos].

Ultrastructural changes of the rat diaphragm muscle fibers and electron histochemical distribution of calcium ions were studied following chlorophos administration in 5, 15 and 45 minutes (dose - 300 mg/kg, intraperitoneally). The local swelling of mitochondrial matrix and the appearance of contractures were found first in postsynaptical region. Then the postsynaptical alterations increased; the swelling and fragmentation of sarcoplasmic reticulum were observed in addition to desorganization of mitochondrial ultrastructure. Granules of the histochemical product were revealed in mitochondria, in the sarcoplasmic reticulum and in filaments. Changes in distribution of calcium ions in the rat diaphragm muscle fibres after chlorophos administration and the role of Ca++ the in the mechanism of muscle alteration discussed.