Abstract
Gastric secretion of acid and pepsin in response to graded doses of intravenous caffeine and corresponding plasma caffeine levels were studied in 4 healthy human volunteers. The threshold for both acid and pepsin secretion was found with an infusion of 160 mg caffeine benzoate per hour. At a plasma caffeine level of about 20 mg/litre the maximal acid response was obtained which corresponded to 44% of the pentragastrin-stimulated maximal output. Four to five cups of coffee consumed over 4 to 5 hours produced a similar plasma caffeine level. A linear relationship was demonstrated between the plasma caffeine levels and the corresponding gastric acid and pepsin outputs. There was in addition a high correlation between the acid outputs and the corresponding pepsin outputs. It was concluded that both acid and pepsin secretion are stimulated by intravenous caffeine administration, but that acid output is stimulated to a greater degree than pepsin output.
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