Intragastric nicotine protects against 40% ethanol-induced gastric mucosal injury despite pretreatment with propranolol or N-ethylmaleimide in rats.
We tested the hypotheses that the protective effect of intragastric nicotine against ethanol-induced gastric mucosal injury is dependent on propranolol- or N-ethylmaleimide-sensitive mechanisms. Propranolol was administered in doses (2 and 20 mg/kg) that provided dose-related blockade of beta-adrenoceptors (significant decreases in heart rate). N-Ethylmaleimide was administered in doses that previously had been shown to increase gastric vascular permeability (10 mg/kg) or inhibit gastric mucosal sulfhydryl compounds (50 mg/kg). At 0.5 hr after these or control subcutaneous pretreatments, the rats received intragastric nicotine (4 mg/kg) or vehicle. One hour later 40% ethanol was given intragastrically. The gastric corpus mucosal lesions were recorded by polaroid photographs after another hour, and their areas measured unbiasedly by computerized image analysis. The results showed that N-ethylmaleimide, but not propranolol, aggravated ethanol-induced gastric mucosal injury. The protective effect of intragastric nicotine was not modified by either pretreatment. We conclude that the mechanism mediating intragastric nicotine protection against 40% ethanol-induced gastric mucosal injury is independent of propranolol- or N-ethylmaleimide-sensitive mechanisms.
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Research and Medical Services, Sepulveda Veterans Administration Medical Center, Center for Ulcer Research and Education, UCLA School of Medicine 91343.
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D000818:Animals; D004305:Dose-Response Relationship, Drug; D000431:Ethanol; D005033:Ethylmaleimide / Q000494:pharmacology*; D005753:Gastric Mucosa / Q000187:drug effects*; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D011292:Premedication; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013272:Stomach Diseases / Q000139:chemically induced / Q000517:prevention & control*
D000431:Ethanol; D009538:Nicotine; D011433:Propranolol; D005033:Ethylmaleimide