Does nicotine administration influence intragastric acidity?

Smokers have an increased incidence of duodenal ulcer with a high relapse rate whether they receive maintenance therapy with H2-receptor antagonists or not. They also tend to be slow healers. The etiology behind this is still unknown, and there is general disagreement as to whether smoking affects gastric secretion. In an earlier study we found a small but significant decrease in intragastric pH a short time after smoking a cigarette. The aim of the present investigation was to study whether intragastric pH changed during nicotine administration per se. Nicotine was given as a nasal spray to eight healthy smokers. Nicotine did not induce any acute detectable changes in gastric acidity when the 5-min period before spraying was compared with the 35-min period after spraying (median pH, 1.47 (25-75 percentiles, 1.40-2.32) and 1.55 (25-75 percentiles, 1.42-2.06), respectively). When different time periods during a day with hourly nicotine administration were analyzed, and the results compared with those of a similar day when placebo was given, nicotine was found to impair postprandial gastric neutralization. Median pH during the lunch hour was 1.93 (25-75 percentiles, 1.80-2.37) after nicotine and 2.86 (25-75 percentiles, 2.37-3.70) after placebo; p less than 0.025. Possible explanations for this might be nicotine-mediated effects on gastric motility or gastrin release.