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

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 (51)Cr 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(+).