Aggregation of platelets in the mesenteric microcirculation of the rat induced by alpha-toxin (phospholipase C) of Clostridium perfringens.

We have investigated the effects of purified α-toxin (phospholipase C) of Clostridium perfringens (Yamakawa and Ohsaka, 1977) on the behavior of cellular components in the microcirculation, using cinematography on a microscopic level and electron microscopy. We demonstrated that after topical application of α-toxin to the mesentery of the rat, rolling of leucocytes along the vessel wall and sticking of leucocytes to the vessel wall occurred in venules but not in arterioles. Some of the leucocytes remained attached to the vessel wall. Thrombi were formed frequently in venules and capillaries, and at a later stage, in arterioles. With time, thrombi increased in number and size, leading eventually to stasis of the blood stream. Thrombi were also observed frequently in the mesenteric microcirculation when toxin was injected into the jugular vein of the rat. The experiments with adenosine pretreatment followed by topical application of α-toxin to the mesentery suggested that the formation of thrombi induced by this toxin does not involve the mediation of ADP. Electron-microscopic examination confirmed the formation of thrombi consisting solely of platelets. It was concluded that thrombosis must be involved as an early step in the pathogenesis of necrosis caused by α-toxin. The death of the animals injected intravenously with α-toxin may be due, at least in part, to thrombosis. It is possible that thrombosis induced by α-toxin may be one of the factors involved in the causation of toxemia often manifested in the late stage of gas gangrene.