Does calcium mediate slowing of gastric emptying by fat in humans?

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.