Abstract
During the course of an investigation by one of us 1 of the effect of vagal stimulation on the production of gastric secretion, it was observed that artificial ventilation considerably diminished the volume of the secretion. To ascertain the factors involved in this effect the following experiments were performed on dogs anesthetized with a chloralose and urethane mixture given intravenously.
1. Gastric secretion was obtained by vagal stimulation in the neck. The right and left nerves were stimulated alternately for 10 minutes each throughout the experiment. 2. Hyperventilation was applied. 3. Hyperventilation was continued at the same rate using an artificial air-carbon-dioxide mixture.
A study was made of the gastric juice, the collecting tubes being changed every 10 minutes. Total and free acid were determined by titration, and total chlorides by the method of Wilson and Ball. 2 The arterial (carotid) plasma carbon dioxide content was determined by the volumetric method of Van Slyke, and the plasma pH by the colorimetric method of Cullen. 3
While the vagi were stimulated the volume of gastric secretion rose gradually over a period of 2 hours to a value of from 8 to 10 cc. in 10 minutes. The free and total acid also rose, the former to a concentration of 0.24 mg. %. The initial arterial CO2 content was 34.8 vols. %, and the pH 7.27; both somewhat low, due probably to primary ether anaesthesia. After this period the CO2 content was 43.3 and the pH 7.33. Artificial hyperventilation was then applied at the rate of 64 per minute, and later at 84 per minute, the respiratory rate up to this point having been 12. The sample immediately following this showed a large increase in volume but no appreciable change in free or total acidity.
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