Intragastric PCO2 in man and calculated gastric bicarbonate concentrations: effect of carbenoxolone sodium

In six normal subjects, ten patients with either gastric or duodenal ulcer or combined duodenal and gastric ulcers and in one with gastric carcinoma, the fasting intragastric PCO2 was measured using a new silicon-coated teflon intragastric catheter connected to a mass spectrometer. PCO2 values ranged from 9 to 38 mm Hg in normal subjects and from 23 to 75 mm Hg in patients. In some patients sharp peaks up to 170 mm Hg were obtained. The pH of the resting juice was measured and the intragastric HCO-3 concentration calculated using the Henderson-Hasselbach equation. Intragastric HCO-3 concentration was 5--136 nmol per litre in normals and 12 nmol-960 mumol per litre in those with dyspepsia, and 6.05 mmol per litre in the patient with gastric carcinoma. Five dyspeptic patients and the one with stomach cancer were given 100 mg carbenoxolone t.d.s. for 72 hours. The fasting PCO2 decreased from a mean of 34.6 +/- 4.89 to 26.6 +/- 2.24 Se mmHg (p less than 0.05) with corresponding changes in HCO-3 concentration. These results suggest that carbenoxolone increased the thickness of the unstirred layer of mucus, making it more resistant to H+ penetration and thus reducing H+ and HCO-3 interaction with consequent lowering of PCO2.