Kinetics of absorption of toxin of Vibrio cholerae.

Autoradography of rabbit intestine exposed in vivo to purified tritiated toxin of Vibrio cholerae showed that pharmacologically important amounts of toxin can be rapidly absorbed despite the relatively large size of the toxin molecule and its affinity for binding to the brush border. Cholera toxin and tritiated nontoxic and tritiated nontoxic control substances of comparable size followed a similar time course in spreading down the surface of the villus, and with respect to the villus greater than crypt gradient of labeling of cytoplasm of the mucosal epithelial cells. Absorption of toxin or biologically active toxin fragments provides a mechanism whereby the basal and lateral areas of the cell, which are rich in adenyl cyclase, could participate in the hypersecretory process.