thromboxane-a2 and Gastritis

Chronic non-specific pulmonary diseases are frequently followed by the development of inflammatory-degenerative and erosive-ulcerative processes in the mucous membrane of the stomach and duodenum. The literature date are presented on the frequency of combination of these conditions, the attempt is made to assess their link from the viewpoint of pathogenesis. Disturbances of respiratory lung function and hypoxia as well as non-respiratory metabolic functions of the pulmonary tissue are regarded as etiological factors of pathological processes in the gastro-duodenal area.

Topics: Adult; Angiotensins; Arachidonic Acid; Arachidonic Acids; Chronic Disease; Duodenal Diseases; Duodenitis; Female; Gastritis; Histamine; Humans; Hypoxia; Leukotriene B4; Lung; Lung Diseases; Male; Middle Aged; Peptic Ulcer; Prostaglandins; SRS-A; Stomach Diseases; Thromboxane A2

Aspirin causes peptic ulcers predominately by reducing gastric mucosal cyclooxygenase (COX) activity and prostaglandin synthesis. Because aspirin circulates for only a few hours, we hypothesized that aspirin's inhibitory effect on gastric COX activity must be prolonged. We performed a placebo-controlled experiment in healthy humans to determine the duration of inhibition of aspirin on gastric mucosal COX activity (PGE(2) and PGF(2alpha) synthesis rates). Recovery of gastric COX activity after stopping aspirin was slow and linear. Seventy-two hours after 325-mg aspirin, gastric COX activity was still reduced by 57% (P < 0.001). Duration of inhibition of gastric COX activity was estimated to be 7-8 days after 325-mg aspirin and 5 days after 81-mg aspirin. Recovery of gastric prostaglandin synthesis after 325-mg but not after 81-mg aspirin occurred at slower rates in subjects with Helicobacter pylori-associated gastritis than in those with normal histology. In conclusion, aspirin inhibits gastric COX activity for much longer than predicted from its pharmacokinetic profile, explaining why aspirin at widely spaced intervals is ulcerogenic.

Topics: Adolescent; Adult; Aspirin; Blood Platelets; Cyclooxygenase Inhibitors; Dinoprost; Dinoprostone; Female; Gastric Mucosa; Gastritis; Helicobacter Infections; Helicobacter pylori; Humans; Male; Middle Aged; Prostaglandin-Endoperoxide Synthases; Regression Analysis; Stomach Ulcer; Thromboxane A2; Time Factors