Mutagenicity in gastric juice.

Mutagenicity has been measured in the gastric juice of 228 patients using the Ames bacteriological test system; while mutagenicity in control and duodenal ulcer patients did not differ from saline controls, mutagenicity was significantly increased compared with controls in patients suffering gastric ulcer (p less than 0.002), carcinoma (p less than 0.002), and in patients after gastric resection (p less than 0.01). A transient rise in mutagenicity was seen following H2 antagonist ingestion (p less than 0.002). Increased levels of mutagenicity were found to correlate closely with gastric juice pH and bacterial count. Histidine concentrations in gastric juice did not explain the mutagenicity results.