Effect of alterations in test meal composition on episodic transpyloric fluid movement in humans

Using real-time ultrasonic imaging we have observed the effect of four different liquid test meals on transpyloric fluid movement and related gastroduodenal motor activity in 10 normal subjects. The mean interval between antral contractions (cycle times), and the frequency of occurrence of related proximal duodenal contractions were similar with all four meals (F = 0.3, for both). Forward (gastroduodenal) flow through the pylorus was observed in 95% of cycles and occurred as up to four brief episodes per cycle, each lasting 2-3 sec. The duration of these episodes with pH 2.8 and pH 7.0 meals was longer than with protein and glucose meals (P less than 0.05). There were, however, fewer episodes of forward flow in each cycle with the pH 2.8 and pH 7.0 meals with the protein and glucose meals (P less than 0.05). Retrograde (duodenogastric) flow was observed in 56% of cycles and occurred, on average, as less than one brief episode lasting about 2 sec each cycle. The pattern of retrograde flow was similar with all meals. Gastric emptying and duodenogastric fluid movement both occur in intermittent brief episodes lasting a few seconds only. Changes in the nature of the test meal cause subtle alterations in the basic pattern of transpyloric fluid movement, presumably reflecting the influence of the meal on control mechanisms governing gastric emptying.