Cytoprotection by sucralfate: role of sulfate ions.

Sucralfate and its component, sucrose octasulfate, are both SO4(2-)-containing compounds shown to protect against acid-peptic injury in rabbit and/or cat esophagi. To determine if sulfate ions (SO4(2-) contributed to this protection, a series of in vitro and in vivo experiments were performed in acid-exposed rabbit esophagi. In the Ussing chamber SO4(2-)-containing solutions significantly reduced the acid-induced decline in electrical resistance (R) observed in controls. This effect was unrelated to buffering of H+, accompanying cation or changes in luminal solution osmolality. Protection by SO4(2-) was specific since other divalent (HPO4(2-] or impermeant anions (gluconate-) failed to reduce the acid-induced decline in R. Protection was confirmed in vivo by showing that acid-perfused esophagi exposed to SO4(2-) had less morphologic damage, higher R and lower permeability to 14C-mannitol and H+ than controls. These results indicate that SO4(2-) have a unique protective action against acid injury to esophageal epithelia, and this action appears to explain the cytoprotective properties of sucralfate.