NICOTINE HAS NO EFFECT ON RAT GASTRIC-MUCOSAL PROSTAGLANDIN GENERATION IN-VITRO

Previous studies have shown that cigarette smoking depresses prostagla ndin generation by human gastric mucosa, but the component of smoke th at is responsible for that action is not known. To investigate whether nicotine has a direct effect on gastric mucosal prostaglandin generat ion, we performed the following study. Eight rats were sacrificed and the stomachs removed. Using a biopsy forceps, small pieces of gastric mucosa were resected and placed in incubation vials containing either buffered Krebs solution alone (control), Krebs solution plus indometha cin (5 mug/ml), or Krebs solution plus one of several concentrations o f nicotine ditartrate (10, 100, 500, 1000 ng/ml). The nicotine concent rations we used ranged below and above the plasma nicotine concentrati ons of smokers shortly after smoking cigarettes. Three separate incuba tions of gastric mucosa were performed per experimental group from eac h animal. After 30 min of incubation, prostaglandin E2 and 6-keto-pros taglandin F1alpha concentrations in the incubation medium were measure d by radioimmunoassay. We found that nicotine at any concentration tes ted had no effect on the generation of prostaglandin E2 and 6-keto-pro staglandin F1alpha by rat gastric mucosa. Thus, this study indicates t hat, if nicotine is involved in the depression of prostaglandin genera tion in the gastric mucosa of smokers, its role is an indirect one and not by direct action on the gastric mucosa.