Study of the duodenal contractile activity during antral contractions.

Aim: To investigate the hypothesis that duodenal bulb (DB) inhibition on pyloric antrum (PA) contraction is reflex.

Methods: Balloon (condom)-tipped tube was introduced into 1(st) duodenum (DD) and a manometric tube into each of PA and DD. Duodenal and antral pressure response to duodenal and then PA balloon distension with saline was recorded. These tests were repeated after separate anesthetization of DD and PA.

Results: Two and 4 mL of 1(st) DD balloon distension produced no pressure changes in DD or PA (10.7 +/- 1.2 vs 9.8 +/- 1.2, 11.2 +/- 1.2 vs 11.3 +/- 1.2 on H(2)O respectively, P > 0.05). Six mL distension effected 1(st) DD pressure rise (30.6 +/- 3.4 cm H(2)O, P < 0.01) and PA pressure decrease (6.2 +/- 1.4 cm H(2)O, P < 0.05); no response in 2(nd), 3(rd) and 4(th) DD. There was no difference between 6, 8, and 10 mL distensions. Ten mL PA distension produced no PA or 1(st) DD pressure changes (P > 0.05). Twenty mL distension increased PA pressure (92.4 +/- 10.7 cm H(2)O, P < 0.01) and decreased 1(st) DD pressure (1.6 +/- 0.3 cm H(2)O, P < 0.01); 30, 40, and 50 mL distension produced the same effect as the 20 mL distension (P > 0.05). PA or DD distension after separate anesthetization produced no significant pressure changes in PA or DD.

Conclusion: Large volume DD distension produced DD pressure rise denoting DD contraction and PA pressure decline denoting PA relaxation. PA relaxation upon DD contraction is postulated to be mediated through a reflex which we call duodeno-antral reflex. Meanwhile, PA distension effected DD relaxation which we suggest to be reflex and termed antro-duodenal reflex. It is suggested that these 2 reflexes, could act as investigative tools in diagnosis of gastroduodenal motility disorders.