Antral control of canine gastric emptying of solids

We wondered whether antral mucosal nerves sense the size of particles in gastric chyme and then activate motor mechanisms that allow only small particles to empty. Four conscious dogs with duodenal Thomas cannulas were fed 100 g of bovine liver, half of which was labeled with cyano[57Co]cobalamin. Duodenal chyme was then collected in 15-min periods for 5 h and poured through a stack of sieves of decreasing pore size, and the percentage of radioactivity recovered on each sieve was determined per hour. Five studies were carried out on each dog before and beginning 2 wk after antral mucosal neurolysis, during which the antral mucosal nerves were divided by dissecting the entire antral mucosa circumferentially free from the surrounding antral muscularis. In the control tests, nearly all liver (93%) emptied as particles less than 1.4 mm in diameter, but the percentage emptied as larger particles increased in the 3rd through 5th postprandial h. After antral mucosal neurolysis, the increase in the percentage of larger particles emptied occurred sooner and to a greater extent, but the overall rate of emptying of liver was not changed. We concluded that antral mucosal nerves have a role in regulating the size of gastric particles emptied, but a minor one.