Marked increase in gastric histidine decarboxylase activity in patients with hypergastrinemia.

Histidine decarboxylase (HDC) activity and histamine content were measured in endoscopic gastric biopsy specimens of 19 control subjects with normogastrinemia and 6 patients with hypergastrinemia. In controls, the HDC activity was 3 fold higher in fundic mucosa (120 +/- 13 fmol/min/mg protein, mean +/- S.E.) than in antral mucosa (39 +/- 5 fmol/min/mg protein). In patients with hypergastrinemia, an extremely high HDC activity (713 +/- 181 fmol/min/mg protein) was observed in fundic mucosa, although the HDC activity in antral mucosa was not significantly different from that of controls. The histamine content in fundic mucosa was also significantly higher in patients with hypergastrinemia than in controls but no significant difference was seen in histamine content in antral mucosa between the two groups. These results are compatible with the hypothesis that in man, as well as in rat, histamine synthesis in fundic mucosa is enhanced by gastrin.