Botulinum toxin in the alimentary tract.

Abstract

The great variation in the susceptibility of different animal species to oral injections of botulinum toxin may conceivably be due either (1) to the destruction or adsorption of the toxin by the intestinal contents, or (2) to the difference in permeability of the intestine to the toxin. Type A botulinum toxin was used in these experiments.

There was no evidence that botulinum toxin was adsorbed by the intestinal contents of guinea pigs in vitro, even where the pH was shifted with M/3000 HCl or Na₂HPO₄.

A loop of small intestine in each of six rabbits was injected with botulinum toxin and perfused with blood from the same animal for intervals varying from 30 minutes to 2 hours and 20 minutes. Very small quantities of toxin were demonstrated in the perfused blood, often only sufficient to produce symptoms of botulism in mice receiving 0.5 cc. quantities. No toxin was ever demonstrated in 0.1 cc.

In each of two hogs a loop or small intestine was perfused in a similar manner. In one case a very small amount of toxin was found in the blood, a mouse receiving 0.5 cc. of serum taken after an hour and a half of perfusion died in 4 days. In the other case toxin was not demonstrated. The toxin introduced into the ligated loop of intestine showed little if any decrease in potency during the course of the perfusion experiments.

Hogs were found to be very resistant to large oral doses of toxin; in some cases as much as ten million M. L. D.'s for mice were fed without producing any ill effects. Toxin was not demonstrated in one cc. of blood taken after 90 minutes from a hog which had been fed nine million (mouse) M. L. D.'s.