Effect of intragastric bile salts on ionic movement across normal human gastric mucosa after intravenous atropine

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Abstract
The effect of intravenous atropine (2·0 mg/70 kg) and intragastric bile salts (5·0-5·5 mM) on ionic fluxes across the gastric mucosa was studied. Serial instillations of bile salts, in 200 ml 160 m-equiv/l HCl with 51Cr as a non-absorbable indicator, were performed in eight normal subjects. Five subjects received a bile salt mixture of 84% taurocholic acid, 14% taurodeoxycholic acid, and 2% taurochenodeoxycholic acid. With HCl alone (controls) the mean net flux into the lumen was 1·4 m-equiv H+, 2·9 m-equiv Cl−, 1·5 m-equiv Na+, and 0·26 m-equiv K+ per 15 minutes after the first instillation. Where atropine plus bile salt was given the loss from the lumen was 5·4 m-equiv H+ (p < 0·01) and 1·9 m-equiv Cl− (p < 0·05) and movement into the lumen was 3·2 m-equiv Na+ (p < 0·01) and 0·20 m-equiv K+ in the corresponding period. Similar but smaller ion flux changes occurred in three subjects who received atropine and pure taurodeoxycholic acid. The net loss of H+ from the gastric lumen was greater after atropine-bile salts than that shown in previous studies with bile salts alone. It is postulated that atropine reduced the volume of endogenous HCl secretion unmasking the loss of H+.