Abstracts
1999 Digestive Disease Week

# 2167 EFFECT OF FIVE DIFFERENT CATECHOLAMINES ON PERISTALSIS IN GUINEA PIG ILEUM
Stefan Scheidl, Thomas Petnehazy, Dept of Internal Medicine, Univ, Graz Austria; Peter Holzer, Dept of Pharmacology, Univ, Graz Austria; Heinz F Hammer, Dept of Internal Medicine, Univ, Graz Austria;

Background: Disturbances of intestinal motility may occurr as a complication of a variety of surgical and nonsurgical conditions and may be exacerbated by the therapeutic use of catecholamines. Aim of the study: To evaluate the effect of dopexamine (dopex), dobutamine (dob) and dopamine (dop), as compared to norepinephrine (nor) and epinephrine (epi), on ileal peristalsis in an experimental model which excludes an effect on blood supply. Methods: A 6-cm segment of guinea pig ileum was mounted in oxygenated Krebs-Henseleit solution. Peristaltic contractions were induced by luminal perfusion with Krebs-Henseleit solution at a rate of 0.35 ml/min against an aboral pressure of 5 cm H2O. Intraluminal pressure was recorded at the oral end of the segment. After 15 min of control either epi (1 nM to 100 nM), nor (1nM-1µM), dop (1nM-50µM), dopex (1nM-50µM) or dob( 1nM-50µM) was added to the organ bath in different concentrations. Recordings were analyzed for pressure threshold required to trigger peristalsis. Each substance was compared to its individual control (paired t-test). Results: Each of the catecholamines tested, except epi, significantly decreased thresholds at low concentrations, reflecting a stimulant action on peristalsis. The most prominent effect, however, was a concentration-related increase in the pressure threshold, culminating in complete blockade of peristalsis at the highest catecholamine concentration used in the study. The potency with which peristalsis was inhibited varied widely for the different catecholamines, the rank order being epi > nor >> dop > dob = dopex. Nor and dop had flatter dose-response curves than the other substances. Summary: There are qualitative and quantitative differences in the effect of catecholamines on peristaltic motility. Dopex and dob are about 500 fold less active in blocking peristalsis than epi.

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