Comparison of the rates of gastric acid secretion in man after ingestion of food and after maximal stimulation with histamine.

The mode of stimulating the parietal cells during gastric function tests in man has changed many times since the introduction of the stomach tube first made this kind of investigation possible. For many years 'the fractional test meal' (Ewald) was used, but the response was often too arbitrary, presumably because the stimulation was inadequate. Other test meals composed of liquid food, with a higher protein content than the Ewald meal, were subsequently introduced. This group of tests gives good information on the acidity occurring in the stomach, but quantitative determination of the acid secretion is not possible owing to the lack of information on the amount and composition of the juice passing through the pylorus. In contrast, the widely used augmented histamine test of Kay (1953) today makes it possible to measure the gastric secretory capacity in milliequivalents H+ secreted per hour. Its greatest theoretical limitation is that it gives information only on the performance of the parietal cell mass under the specific test situation and leaves the important question open, Does the maximal histamine stimulation represent a completely unphysiological stress, provoking an excessive acid output which bears little or no relation to the acid secretion following ingestion of food? In other words, How intense is the gastric acid secretion when we eat normal food? In order to answer this question a technique was developed for measuring the gastric secretion of acid without involving aspiration of the stomach contents (Rune, 1965). It is based on the concept that for each equivalent amount of hydrochloric acid secreted into the stomach lumen an equivalent acid deficit will arise in the rest of the body. Calculating this acid deficit from measurements of the base content in multiple arterial blood samples allows estimation of the gastric acid secretion in man during the augmented histamine test. This paper presents the results obtained by applying the same method during digestion of normal solid food in human subjects.