Effect of cholera enterotoxin preparations on cutaneous response in rabbit under varied conditions.

Enterotoxic activity of two preparations obtained from Vibrio cholerae, B-53-6 Inaba and B-53-10 Ogawa was tested in ligated ileal loops of rabbit. The biologically active enterotoxic preparations were further used to study the permeability reaction in rabbit skin. Cutaneous response tended to be linear only with higher concentrations of the toxin and showed maximum blueing intensity between 16 and 24 hrs of intracutaneous inoculation. Exposure of enterotoxin preparations to elevated temperatures greatly reduced the cutaneous response and the activity was completely lost at 100 degrees C. Change in pH towards alkaline side lowered the permeability activity to lesser extent as compared to a shift on acidic side. However, a residual activity could still be detected when pH of the enterotoxins was lowered to 3 at 30 degrees C for 4 hrs.