An experimental study of the gastrointestinal motility in conscious dogs with strain gauge force transducers

Abstract

Interdigestive motor complex (IMC) from the stomach to the ileum and colonic migrating motor complex (CMMC), and the effects of motilin and PYY to them were studied in conscious dogs with strain gauge force transducers (SG). In fasted dogs, IMC cycle times were 100.5 +/- 7.5 min in from the antrum to the ileum and propagation velocity of the small intestine was fastest in the proximal jejunum (4.85 +/- 0.81 cm/min), slowest in the distal ileum (0.81 +/- 0.08 cm/min). The duration of postprandial interruption of motor complex (DIMC) was longer in the antrum and duodenum in 8 dogs of the twelves than the middle and lower intestines. Ileo-colonic propagation rates of IMC that reached to the terminal ileum were 95/116 (81.9%), but the frequency of CMMCs was about 4 times higher than that of IMCs. Each colonic motor complex were classified into four patterns, such as aboral migrating complex (A), oral migrating complex (O), discrete complex (D) and giant migrating contractions (G), and the starting point of migrating complex was marked with -, like A, O or G. Thus, independency index (I I) in each site was defined as: I I = (sum of number of A, O, G and D)/(total number of colonic motor complex). I I was highest in colon 1 (70-80%) and next in colon 4. Motilin (0.5 microgram/kg.hr) elicited IMC like activities in the antrum, duodenum and proximal jejunum, but no effects in the middle and lower small intestine, and the colon. PYY infusion caused dose dependent inhibitions of IMC in the antrum and duodenum, but no effects in the below intestines as same as motilin. These findings suggest that IMCs are basal rhythms of gastrointestinal motility and IMCs occurring from the antrum to the proximal jejunum are more sensitive to the factors as eating or gut peptides.