Ricinoleic acid (castor oil) alters intestinal surface structure. A scanning electronmiscroscopic study

To determine if sodium ricinoleate, the active principle of castor oil, alters mucosal surface structure of the small intestine, rabbit ileum was perfused with isotonic buffer or buffer containing 10 mM of sodium ricinoleate. Mucosal biopsies were examined by scanning electron microscopy. Sodium ricinoleate produced deep clefts or holes at the tips of villi, and at the bases of these clefts unusual cells could be resolved. The microvillus surface of the intestine was also altered at the tips and sides of villi. Microvilli were clumped into "tufts" with numerous intervening "cracks" appearing on the surface. These changes may relate to the well-documented capacity of ricinoleate and dietary long-chain fatty acids to evoke fluid secretion in the intestine. The findings thus pertain to the pharmacology of castor oil and the pathophysiology of steatorrheal disease.