Intestinal permeability in the irradiated ferret.

Abstract

Ferrets received whole-body irradiation (5 Gy, gamma). At different times post-irradiation (PIRR, 2, 24, and 48 hours), measurements of fluid and electrolyte fluxes, and of the blood-to-lumen clearance of $\sp{51}$Cr-EDTA, were compared between in situ perfused loops of jejunum and ileum. Intestinal permeation of $\sp{51}$Cr-EDTA was increased (4x control) in both the jejunum and ileum at 2 hours PIRR. At 24 hours PIRR, $\sp{51}$Cr-EDTA permeation was the same as control. At 48 hours PIRR, jejunal permeation of $\sp{51}$Cr-EDTA was not statistically different from control animals, whereas in the ileum, $\sp{51}$Cr-EDTA permeation was increased 10x control. Absorption of luminal fluid was abolished 2 hours PIRR in the ileum. Sodium and chloride fluxes were unaffected by radiation exposure, but at 48 hours PIRR there was a significant secretion of potassium in the ileum. Diarrhea rarely occurred after the first hour post-irradiation. Serotonin, acting via 5-HT$\sb3$ receptors, was investigated as a possible mediator of radiation-induced alterations in intestinal permeability. Pretreatment with the 5-HT$\sb3$ antagonist and anti-emetic BRL 43694 significantly reduced the severity of radiation-induced vomiting. It offered some therapeutic benefit to radiation-induced diarrhea. However BRL 43694 pretreatment had no effect on intestinal permeability. (Abstract shortened by UMI.)