Ultrastructural Changes in Heart Muscle Associated with Anaphylaxis in the Guinea Pig

The ultrastructural changes of heart muscle following anaphylactic shock induced by egg white injection have been studied with guinea pigs to elucidate the exact nature of the cardiac anaphylaxis. The main changes were observed in the contractile elements and they consisted of dissociation of myofibrils from intercalated discs, fragmentation of intercalated discs, lengthening of sarcomere with contraction of adjacent several sarcomeres, and fragmentation and disarrangement of myofilaments. The other changes were shrinkage or disruption of mitochondria, dilation of endoplasmic reticulum, appearance of numerous vacuoles between and inside the myofibrils, and slight increase of glycogen granules. In these changes of the heart muscle, those of the contractile elements and the mitochondria seemed to have resulted from the direct effects of anaphylactic reaction, and dilation of endoplasmic reticulum and appearance of numerous vacuoles were considered to be caused by anoxic effects of respiratory disturbance or reduction of coronary blood supply due to anaphylactic reaction. The increase of glycogen granules seemed to be caused by disturbance of oxidative enzymes in the mitochondria. These findings suggested that the effects of anaphylactic reaction on the heart muscle resulted from the direct toxic effects of anaphylactic reaction rather than the hypoxia or ischemia due to respiratory disturbance or reduction of coronary blood supply, and they seemed to support the conception that the heart should be considered to be a potential “shock organ” in the anaphylactic reaction.