[Effects of buprenorphine on gastrointestinal interdigestive myo-electric complex in dogs].

The effect of buprenorphine on the interdigestive myoelectric complex (IMC) was studied by gastrointestinal electromyogram in 3 mature mongrel dogs. The electromyograms were used to study the IMC cycle and total elapsed time (TET). Buprenorphine had very strong hyperkinetic action on the gastrointestinal tract at doses of 1 and 2 micrograms/kg which revealed phasic contraction, but since this action disappeared when atropine was administered. The phasic contraction originated in the upper jejunum just under the ligament of Treitz and then showed a migration pattern of J-->D and J-->I in 11 out of 23 cases (47.8%), D-->J-->I in nine cases (39.1%), J-->D-->J-->I in one case and no response in two cases. TET (min) showed a mean value of 90.3 +/- 11.2 (n = 23), which was not significantly different from the controls (106.1 +/- 14.3) (n = 24), but tended to be longer (0.1 > p > 0.05). After administration of buprenorphine at a dose of 20 micrograms/kg, phasic contraction migrated to ileum, which was disappeared an interval of 6-7 hours until next IMC. At low doses of buprenorphine were administered after a meal, the postprandial pattern was restored and converted to fasted pattern only one IMC cycle. Buprenorphine is partial agonist for the mu receptor. Ahmad et al. (1989) reported that alpha 2 adrenergic receptor and opiate receptors (mainly mu) were presented in submucosal plexus. In concludes that alpha 2 adrenergic activity and other humoral factors seems to take an important role for the initiation of phasic contraction and to control maintenance of IMC cycle.