Vanadium-induced Cl−-secretion in rabbit descending colon is mediated by prostaglandins

Abstract Vanadium in the 4+ (vanadyl-ion) and 5+ (vanadate-ion) oxidation state stimulates furosemide-sensitive electrogenic Cl − secretion in isolated epithelia of rabbit descending colon. This effect is associated with an increased release of prostaglandin E 2 from the tissue. Inhibitors of phospholipase A 2 or cyclooxygenase abolish both vanadium-induced release of prostaglandin E 2 and Cl − secretion. Neuronal mechanisms are not likely to be involved, as tetrodotoxin does not affect the vanadate induced Cl − secretion. Although vanadate is known to inhibit Na + , K + -ATPase activity, no inhibition of active Na + transport was observed in intact colonic epithelia suggesting a rapid intracellular reduction of vanadate ions to vanadyl ions which have no inhibitory effect on the Na + , K + -ATPase. The present findings therefore indicate that vanadate stimulated colonic Cl − secretion involves intracellular conversion of vanadate to vanadyl and release of prostaglandin E 2 .