[Inhibition of the interdigestive myoelectric cycles in dogs by a single administration of bile acids into the branch of the cranial mesenteric artery].

Abstract

Experiments were performed on 10 fasted dogs equipped with perfused catheter which was placed into the branch of the cranial mesenteric artery supplying the short duodenal or jejunal segment. In addition, 9 bipolar electrodes for electromyographic examinations were implanted into the stomach and small bowel including the perfused intestinal segment. Na-taurocholate, Na-taurodeoxycholate (TD) and Na-taurochenodeoxycholate were infused for 2 hr in 2 different doses (reaching in blood, which supplies the intestine, the concentration about 7.5 and about 50 mumol.l-1) or injected for 0.5 min (reaching the concentration about 200 mumol.l-1 in the blood) close intraarterially to the animals. The lower dose of bile acid infused caused no significant changes in myoelectric activity. The higher dose of bile acid infused significantly inhibited the occurrence of action potentials (prolongation of phase I of the migrating myoelectric complex) for the period much longer than the bile acid infusion itself. Both stimulatory (the phase III-like myoelectric activity, vomiting) and inhibitory effects of action potentials as well as changes in frequency and amplitude of resting potentials were triggered by bile acid injection. Alterations induced by TD administration were the strongest. The immediate appearance of the inhibitory effect suggests the mediatory role of the nervous system in this response. In normal conditions the bile acids appear to regulate the motor function of the digestive tract solely when they enter the intestinal lumen. Their raised level in plasma, as observed in many liver and biliary tract diseases must give, as a consequence, an unfavourable effects which may be a cause for the arrival of gastrointestinal manifestations (the motor component) during a course of above affections.