Jerry S. Walker

NEUROLOGICAL AND PHYSIOLOGICAL RESPONSES OF THE PRIMATE TO ANTHRAX TOXIN

Abstract : Anthrax toxin depressed the cerebral cortical electrical activity of both anesthetized and non anesthetized monkeys and anesthetized chimpanzees. Recordings on a physiograph recorder revealed changes in electrocardiogram and hypoxic hypertension that progressed with the degree of intoxication to final cardiovascular collapse. Changes in cortical electrical activity were either partial or complete, and in some cases cortical activity was depressed in cyclic patterns that appeared independent of other observed physiological changes. Subcortical changes in electrical activity occurred simultaneously with the surface cortical changes. The protective antigen component of the toxin alone caused the initial changes in surface cortical activity. Those animals that died showed a respiratory failure that appeared to be of central nervous system origin involving the respiratory center of the brain. Survival with no changes in physiological or cortical electrical activity occurred in monkeys pretreated (30 min) or postreated (up to 8 hours) with specific antiserum.

Effect of Temperature and Drug Therapy on Anthrax Intoxication

Summary In contrast to other known bacterial toxins and venoms, challenge with anthrax toxin resulted in a hypothermia which is as great as 14-15°C in animals stressed by holding at 4°C. In comparison with animals held at room temperature following challenge, mean time to death is shortened in those animals held at 37°C and extended at 4°C became more susceptible to anthrax toxin, being killed by 8 rat units of toxin, whereas 16 units were required to kill animals held at room temperature. Antiserum, if administered through 60 minutes, prevented death of rats challenged with 15 units of toxin and tended to extend time to death of rats challenged with higher dosages of toxin. For animals challenged with 30 units of toxin and held at 24°C, the drugs, caffeine, N-allyl-morphine, ACTH, hydrocortisone and barbituate were ineffective except for barbituate which extended time to death. All drugs were ineffective for rats stressed at 4°C.