Demonstration of the cardiotoxicity of the thermostable direct hemolysin (lethal toxin) produced by Vibrio parahaemolyticus.

Intravenous injection of the thermostable direct hemolysin (lethal toxin) produced by Vibrio parahaemolyticus caused rapid death of rats. Studies by electroencephalography and electrocardiography showed that after intravenous injection of the toxin the electroencephalogram remained normal for quite a long time after the heart of the animals had stopped beating. Depression of intraatrial and intraventricular conduction of electrical activation, including atrioventricular block, was observed in electrocardiograms of animals injected with the toxin. The toxin was also found to be toxic to cultured mouse heart cells. When it was added to the medium, the beating rhythm of the cultured heart cells increased temporarily and then soon stopped abruptly. The effect of the toxin on cultured mouse heart cells was blocked by preincubation of the toxin with a ganglioside mixture. From these results it is concluded that the thermostable direct hemolysin (lethal toxin) had cardiotoxic activity, and thus administration of the toxin causes rapid death of animals.