Gastric emptying and its relationship to antral contractile activity

Gastric emptying and antral contractile activity were simultaneously measured in 3 dogs with gastric and duodenal fistulas. Contractile activity was monitored by two force strain gauge transducers on the serosal surface of the antrum of 2 dogs and a single strain gauge transducer on the serosal surface of both the antrum and fundus of the 3rd dog. Both the frequency and force (motility index) of antral contractions were determined for each 1 min period. Gastric emptying and contractile activity were recorded and compared minute by minute with test meals (154 mM saline) of 60, 120, 240, and 480 ml. Although the rate of gastric emptying increased with the frequency and force of antral contractions, up to 67 ml min-1 (mean 6.9 ml min-1) were emptied without measurable antral contractile activity and 0 to 96 ml min-1 (mean 19.4 ml min-1) were emptied during maximal antral activity (minute motility index greater than 119 mm). Antral contractile activity increased with the size of the test meal and decreased expoentially with the rate of gastric emptying. Fundal contractile activity was generally absent during the test meal. These studies suggest that although the antrum has a significant role in the emptying of liquids, other undefined factors may modify its effect on gastric emptying.