MOTOR-ACTIVITY AND TRANSIT IN THE AUTONOMICALLY DENERVATED JEJUNUM

The role of extrinsic (autonomic) innervation in postprandial contract ile activity of the small intestine is unknown. Using a canine model, we investigated the effects of complete extrinsic denervation on the p arameters of fasting and postprandial jejunal contractions and their r elationship to intestinal transit. Individual contractions were record ed using strain gauge transducers. Spatial a;ld temporal parameters of contractions were analyzed by computer methods. Bolus injection of C- 14-polyethylene glycol was used to calculate intestinal transit rates. Statistical comparisons of control and denervated animals were made b y nonparametric tests. Extrinsic denervation did not abolish fasting o r fed motor activity, but the following effects were observed: (1) the frequency of migrating motor complexes (MMCs) increased; (2) the onse t of fed motor activity was delayed, and the duration of fed activity was shortened; (3) frequency, mean amplitude, and mean area of postpra ndial contractions were decreased; (4) fewer contractions propagated d istally, and mean propagation distance was shortened; and (5) intestin al transit was slower for solids, but not for liquids. In the small in testine, extrinsic nerves modulate motor activity, which is under prim ary control of the intrinsic (enteric) nervous system.