AJP - Gastrointestinal and Liver Physiology, Vol 244, Issue 1 89-G94, Copyright © 1983 by American Physiological Society
Does calcium mediate slowing of gastric emptying by fat in humans?
J. N. Hunt
The relative potencies of 47 compounds in slowing gastric emptying in one
subject are given. The majority of the most effective compounds are
detergent, but all detergents do not slow gastric emptying. It is proposed
that the property common to those detergents that slow gastric emptying is
the binding of ionized calcium. Disodium edetate (EDTA) is not a detergent.
It has a high affinity for calcium, and it slows gastric emptying strongly.
Reasons are given for proposing that decreasing the volumes of the lateral
intercellular spaces of the luminal half of the duodenal villi mediates the
slowing of gastric emptying by carbohydrate, protein, fats, and acids.
Osmotic stimuli in the duodenal lumen, or in the enterocytes, reduce the
flux of water into the lateral intercellular spaces. Anions of fatty acids
and hydrogen ions displace calcium from a site on the tight junctions at
the luminal border of the enterocytes. As a result, the tight junctions
become more permeant to water and the lateral intercellular spaces shrink
as their content drains into the duodenal lumen. Shrinking of the lateral
intercellular space is proposed as the final common event in the
transduction of the duodenal stimuli that slow gastric emptying.
