[Development of an animal model of autonomic over-activity in tetanus]

Although present day progressive respiratory management has decreased the tetanus mortality rate, tetanus-related autonomic overactivity remains a lethal condition. The cause, pathophysiology, and treatment of this condition are controversial and no animal model has ever been reported. So we tried to make a rabbit model of this condition. At first we injected 30 micrograms of purified tetanus toxin intravenously. Blood pressure oscillation occurred, but the degree of oscillation was smaller than that was seen in the clinical cases. The degree of oscillation had not changed by addition of 30 micrograms purified toxin 12 hours after first injection. Secondly, 7 days before the experiment we injected 0.5 micrograms of purified tetanus toxin intravenously. On the experiment day, we injected 30 micrograms of purified toxin again. By this method there occurred blood pressure oscillation as same as that was seen in the clinical cases. But no rabbits progressed to circulatory collapse by purified toxin. Then to the last group of rabbits, we injected crude tetanus toxin for purified toxin. The degree of blood pressure oscillation was same as that of cases in which purified toxin was injected, and all rabbits progressed to circulatory collapse.