Sieving of solid food by the canine stomach and sieving after gastric surgery

Present concepts on the gastric emptying of solid materials derive from experiments with plastic spheres now known to be emptied differently than food. Accordingly, experiments were undertaken with radiolabeled chicken liver to assess (a) the size of meat particles passed by the normal canine stomach and (b) the effects of ulcer surgery on the rate of emptying and the size of emptied meat particles. Control or ulcer-operated dogs were prepared with chronic duodenal fistulas from which chyme was collected after a standard meal of beefsteak + radioliver + water. Collected chyme was sieved over a stack of sieves of decreasing pore size, and the percent of radioactivity recovered on each sieve was determined each postcibal hour for 5 hr. Control dogs emptied the meal slowly, and virtually all recovered meat was emptied in particles equal to or less than 2.0 mm. Dogs with vagotomy (V), pyloroplasty (P), vagotomy + pyloroplasty (V + P), or antrectomy with end-to-end (A-BI) or end-to-side (A-BII) gastroduodenostomy did not empty the meal faster than the control dogs. In all ulcer-operated dogs except those with P, there were significant upward shifts in the size of meat particles emptied from the stomach; but changes were marked only dogs with V + P or A-BII. Although the experiments verify the antral sieving mechanism noted in earlier work with plastic spheres, the trituration of solid food is probably more complex than previously envisioned.