Perfusion of rabbit colon with ricinoleic acid: dose-related mucosal injury, fluid secretion, and increased permeability.

Morphology of the rabbit colon was examined by light and scanning electron microscopy after perfusion of the organ with 2.5, 5.0, 7.5, and 10 mM sodium ricinoleate. Colons perfused with control buffer showed the expected normal appearances, whereas ricinoleate produced desquamation of surface epithelial cells. Surface changes in the colon were comparable with those reported after similar treatment of the rabbit ileum. Concomitant with these histological changes was loss of DNA into the lumen of the colon. Dose-related changes in net fluid transport and mucosal permeability (as assessed by lumen to plasma flux of low molecular weight polyethylene glycols and plasma to lumen flux of urea and creatinine) were also associated with ricinoleate perfusion. These structural and functional alterations may contribute to intraluminal accumulation of fluid and catharsis that can result from administration of ricinoleic acid (castor oil). The findings might also pertain to the pathophysiology of steatorrheal diseases, because dietary fatty acids of similar chemical structure are known to have comparable effects on the intestinal mucosa.