A new method for quantitation of ion fluxes across in vivo human gastric mucosa: effect of aspirin, acetaminophen, ethanol, and hyperosmolar solutions.

A new, sensitive, and reproducible method for measuring hydrogen and sodium ion fluxes across the human gastric mucosa was developed and validated. By the use of a double-balloon tube that obstructed the pylorus, the stomach was converted into an in vivo Pavlov-type pouch. Duodenogastric reflux was prevented, and emptying of gastric contents into the duodenum was, on the average, 6%, thereby eliminating two important sources of error in quantitative gastric ion fluxes in humans. Transmucosal potential difference and endoscopic appearance of the gastric mucosa were also evaluated during each experiment. The mean percentage variation between duplicate tests for hydrogen ion was 3.2%, for sodium 17.5%, and the potential difference was 2.5%. Instillation of acetylsalicylic acid (36 mM, 1300 mg) in 200 ml of 100 mM hydrochloric acid for just 15 min resulted in a mean net hydrogen ion loss of 3.4 mmol/15 min, a net sodium ion gain of 1.9 mmol/15 min, a decrease in the potential difference of 23 mV, and marked gastric mucosal changes. Furthermore, exposure for 15 min to 20% ethanol (vol/vol, in 200 ml of 100 mM hydrochloric acid) and two separate hyperosmolar solutions (3600 mosmol/kg and 1800 mosmol/kg, both in 200 ml of 100 mM hydrochloric acid) also resulted in marked changes of net hydrogen ion loss (3.1, 4.8, 5.2 mmol/15 min, respectively), net sodium ion gain (2.4, 3.3, 2.4 mmol/15 min, respectively), decrease in potential difference (32, 30, 36 mV, respectively), and gross damage to the gastric mucosa. Each parameter was significantly different from the control test. Acetaminophen (86 mM, 2600 mg) or 10% ethanol (vol/vol) in 200 ml of 100 mM hydrochloric acid did not significantly alter ion fluxes or potential difference. Acetaminophen also did not significantly alter the endoscopic appearance of the gastric mucosa, whereas 10% ethanol had only a modest effect. In the control, aspirin, and acetaminophen experiments, maximal changes in the four parameters (i.e., hydrogen and sodium ion fluxes, potential difference, and endoscopic score) were significantly correlated with one another.