Histological and histochemical examinations of the myocardium of rats kept on low-magnesium diet and treated with cyclophosphamide.

Cyclophosphamide administered intraperitoneally in 20 mg/kg doses at intervals of six days for six weeks caused focal morphological and histochemical lesions of low intensity in rat myocardium. From the third week of the experiment focal eosinophilia and fuchsinophilia of the cytoplasm of a part and later on, of the whole cytoplasm of myocardial fibres, contraction nodes, undulant shape of the fibres, rupture of intercalated discs, very rarely in the sixth week small focal infiltrations composed of mononuclear cells at the site of damaged and disintegrated myocardial fibres, small amount of glycogen, focal increase of acid phosphatase activity and low-grade loss of alkaline phosphatase and magnesium and calcium-dependent ATPases in the sixth week, and unchanged activity of succinic dehydrogenase. Simultaneous use of cyclophosphamide and low-magnesium diet increased the intensity of degenerative changes, which appeared from the second week on, and necrotic changes appearing from the third week on, with more pronounced disturbances in the activity of all studied enzymes, including succinic dehydrogenase, in the sixth week.