Ricinoleic acid stimulation of active anion secretion in colonic mucosa of the rat.

Perfusion of the colon with ricinoleic acid produces fluid and electrolyte accumulation. The mechanism of these changes in water and electrolyte movement is uknown. These studies were designed to determine whether ricinoleic acid effects active ion transport across isolated rat colonic mucosa. 0.5 mM Na ricinoleate produced significant increases in potential difference (3.8 +/- 0.5 mV) and short-circuit current (Isc) (99.2 +/- 10.1 muA/cm2). The increases in Isc produced by Na ricinoleate were inhibited by both removal of bicarbonate and chloride and by the presence of theophylline. The hydroxy fatty acid also resulted in a significant decrease in net Na absorption from 4.7 +/- 0.8 to 0.1 +/- 0.7 mueq/h cm2 and reversed net Cl transport from absorption (+ 4.5 +/- 0.9) to secretion (-2.2 +/- mueq/h cm2). In parallel studies 0.5 mM Na ricinoleate increased mucosal cyclic AMP content by 58%. The concentrations of Na ricinoleate required to produce detectable and maximal increases in both Isc and cyclic AMP were the same. These results provide evidence in support of the concept that hydroxy fatty acid-induced fluid and electrolyte accumulation is driven by an active ion secretory process.