Ultrastructural Changes of Heart Muscle in Cyanide Poisoning

Abstract

Electron-microscopic changes of the heart muscle of rats after administration of cyanide were described in detail with the purpose of demonstrating the direct effects of cyanide on the heart muscle.
The most prominent electron-microscopic changes were elongation of the sarcomere, dissociation of the myofibrils at the level of I band, swelling, destruction and disappearance of the mitochondria, enlargement of the vesicles of sarcoplasmic reticulum, margination of chromatin granules in the nucleus, and swelling of the capillary endothelial cells. These findings were most prominent in cases of death in 10 to 15 minutes after injection of 10 mg per kg of potassium cyanide. On the other hand, the above changes were slight in cases of death within 5 minutes after the same dosage, because the rats died rapidly from paralysis of the respiratory center rather than cardiac disturbances. The rats with the dosage of 2 mg per kg of potassium cyanide survived cyanide poisoning, and the ultrastruc-tural changes in 15 minutes after the injection were only slight swelling of mito-chondria and of vesicles of sarcoplasmic reticulum, and these changes were not found in 60 minutes after the injection.
These results suggest that the cyanides in a larger dose exert a direct influence nott only on the metabolic systems but also on the contractile elements of the heart, muscle, but those in a smaller dose cause only slight and reversible changes in the metabolic systems.