Cyclic GMP-dependent cytoprotection against ethanol-induced damage in rabbit isolated gastric parietal cells.
Prostaglandin E2 stimulates a nitric oxide/cyclic GMP (NO/cGMP) pathway which activates basolateral Cl- channels in rabbit gastric parietal cells. We examined whether the NO/cGMP pathway protects parietal cells from ethanol (EtOH)-induced cytotoxicity, using a parietal cell-rich suspension purified from rabbit gastric mucosa. Cytotoxicity was assayed by measuring the release of a fluorescent dye from the cells. N2,O2-dibutyryl guanosine 3',5'-cyclic monophosphate (DBcGMP) showed a concentration-dependent protective effect against EtOH-induced cytotoxicity. The half-maximal effect of DBcGMP was observed at 24 microM. DBcGMP in a concentration-dependent manner opened the basolateral Cl- channels of parietal cells, the EC50 value being 44 microM. The EtOH-induced cytotoxicity decreased as the Cl- concentration of medium decreased. A 30-s treatment with 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), an inhibitor of the Cl- channel, had a cytotoxic effect which was not prevented by pre-incubation with DBcGMP. The cytotoxic effects of EtOH and NPPB were additive and the NPPB effects did not depend on the medium Cl- concentration. The present study showed that cGMP protects the gastric parietal cell from EtOH-induced cytotoxicity, and this cytoprotection is related to basolateral Cl- channel activity in the plasma membrane via an unknown mechanism(s).
Sakai
H
H
Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
Ikari
A
A
Shimizu
T
T
Sato
T
T
Takeguchi
N
N
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D018118:Chloride Channels / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000009:adverse effects*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009579:Nitrobenzoates / Q000009:adverse effects; D009599:Nitroprusside / Q000494:pharmacology; D010295:Parietal Cells, Gastric / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D018408:Patch-Clamp Techniques; D011817:Rabbits; D014665:Vasodilator Agents / Q000494:pharmacology; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D002121:Calcium Channel Blockers; D018118:Chloride Channels; D002712:Chlorides; D009579:Nitrobenzoates; D014665:Vasodilator Agents; D062367:ortho-Aminobenzoates; D009599:Nitroprusside; D003995:Dibutyryl Cyclic GMP; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D000431:Ethanol; C001209:fenamic acid; D006152:Cyclic GMP