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GASTROINTESTINAL, HEPATIC, PULMONARY, AND RENAL

Isothiocyanate Inhibits Restitution and Wound Repair after Injury in the Stomach: Ex Vivo and in Vitro Studies

Department of Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts (R.R., E.N., L.M., S.Y., S.J.H.); and Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan (E.N., S.H., K.T.)

The role of isothiocyanate (ITC) in blocking epithelial restitution after injury and in the recovery of round wounds was examined in the ex vivo guinea pig stomach and in rat gastric mucosal-1 (RGM1) cells, respectively. For this, recovery of transepithelial electrical resistance and morphology after injury or the closure of round wounds was evaluated in the presence of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or 4,4-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid (H₂DIDS) (two ITC groups), 4-acetamido-4-isothiocyanatostilbene-2,2'-disulfonic acid (SITS) (one ITC group), or 4,4-diinitrostilbene-2,2'-disulfonic acid (DNDS) (no ITC groups). Wounded RGM1 cells were also incubated with bicarbonate-free buffer, ATP, barium, or phloretin to determine the mechanism of ITC inhibition. At 300 µM, DIDS or H₂DIDS blocked restitution and wound repair by 100%, SITS blocked wound repair by 50%, and DNDS blocked wound repair by 2%. These results demonstrate the dependence of restitution and wound repair on ITC. ITC-binding purino (ATP) receptors and K_ATP channels were investigated as potential sites of inhibition, but they were found not to be the target of ITC in wound repair. Phloretin, blocking the monocarboxylate transporter (MCT), dose-dependently inhibited wound repair, and this result was exacerbated when the sodium bicarbonate cotransporter (NBC) was also blocked by bicarbonate-free conditions, resulting in 100% inhibition of wound repair with no reduction in viability when both transporters were blocked simultaneously. ITC potently inhibits both MCT and NBC, which may account for the inhibitory action of DIDS during restitution and wound repair. Reverse transcription-polymerase chain reaction data verified that MCT-1 is expressed in RGM1 cells. In conclusion, our results suggest that bicarbonate and monocarboxylate transport may work cooperatively to facilitate restitution of the gastric mucosa after injury.

Address correspondence to: Dr. Susan J. Hagen, Department of Surgery, E/DA-805, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215. E-mail: shagen{at}bidmc.harvard.edu