ABSTRACT
In the late 1940s and early 1950s considerable advances were made in the study of intestinal absorption: these eventually led to an understanding of the principles underlying the processes of intestinal epithelial transport. The advances were based on new methods of studying absorption in vitro and on new analytical techniques. It became realized that to sustain successfully the small intestine in vitro it was necessary that the mucosal surface of the segment was exposed to a well-oxygenated, buffered, balanced saline solution. Glucose in the lumen stimulated fluid and salt transport, the nonmetabolized galactose having no such effect. Thus by the mid 1950s, the notion of metabolism by the epithelium of absorbed carbohydrate was well established. Possibly the manometric method used to measure glutamate also measured glutamine so that what was observed was glutamine utilization by the dog intestine. In fact, glutamate and aspartate disappeared from the system and it was suggested that these amino acids had been subjected to transamination.
