S90

BOMBESIN RELEASES MOTILIN IN DOG. P.Poitras, D.Tass~ and P.Laprise. St-Luc Hospital, Clinical Research Center, Montreal, Canada.

In conscious dogs with 8 electrodes implanted in the small intestine bombe- sin (BBS) effects on motilin release and myoeleetrical intestinal activity we- re verified. A) In a first set of experiments, BBS infusion started precisely 30 minutes after the end of a recorded activity front in ~roximal duodenum. BBS was administered stepwise at 0.25, 0.5 and 1.0 ~g kg- hr -I for 20 minutes each in 4 dogs. During BBS administration, blood levels of motilin were signi- ficantly higher than those measured at the exact corresponding times of the preceeding interdigestive complex during infusion of saline. BBS ~g kg -~ hr ~ Minutes after activity front +30 +40 +50 +60 +70 +80 +90 Mean Motilin Saline 120.25 120.5 108.25 i01.0 116.5 146.0 136.0 c o n e .

Fmol m1-1 BBS 116.75 141.5 206.75 233.5 256.75 238.25 250.25 P N.S. N.S. <0.025 <0.025 <0.01 <0.05 <0.025

B) BBS was then infused at 0.5 pg kg -i hr -~ for 40 minutes in 8 fasting dogs, but without any knowledge of the intestinal activity, and blood was obtained each 10 minutes. In comparison with preinfusion levels, no rise in serum moti- lin could be detected. C) When BBS was infused at 0.125 or 0.5 pg kg -1 hr -l for 3 hours, no activity fronts were observed in any of the 4 dogs despite elevated motilin blood levels. A specific pattern of myoelectrical activity characterized by an increased frequency and a decreased amplitude of the pace- setter potentials was promptly induced. After a mean time of 42 minutes, a mo- derate spike activity superimposed on a hardly discernable and often irregular basal electrical rythm took place and lasted until the end of the infusion. Conclusion: i) BBS releases motilin in the fasting dog; 2) a specially design- ed experimental protocol taking into account the irregularity of the inter- digestive process is absolutely required to detect the effect of BBS; 3) BBS inhibits the occurence of activity fronts and induces a specific myoelectrical pattern; 4) the ¢contradictory~ effects of BBS on motilin release and intesti- nal motility are of doubtfull physiological importance.

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EFFECTS OF XYLITOL ON GASTRIC EMPTYING, INTESTINAL TRANSIT AND MOTII_IN RELEASE. Salminen, S,, Salminen E,, Porkka, L,, Kwasowski, P~, Marks, V.

University of Surrey, Guildford, Surrey GU2 5XH, United Kingdom.

The effects of xyl i toI and glucose on gastric emptying and intestinal mot i l i ty were studied in human volunteers. The volunteers were served 30 g of xyl i to l or )0 g of glucose in random order after a 12-hour fast. Each dose was mixed with 200 ml of distil led water. Gastric emptying and intestinal transit were observed using a 99m-Tc-tin colloid marker mixed with the carbohydrate solutions. The passage of the marker Was followed for 70 minutes by gamma camera techniques. Plasma levels of moti l in following ingestion of xyl i tol and glucose solutions were deter- mined from serial samples of venous blood collected for 120 minutes. Moti l in was analysed by a radioimmunoassay developed at the University of Surrey. The volunteers had not previously taken xyIitol. The results indicated that xyl i toI caused a transient but significant increase in plasma moti l in levels when compared with glucose. The subjects receiving xyl i to l complained of diarrhoea, nausea and early satiety. No untoward effects were observed after glucose consumption. Gastric emptying was significantly delayed after xyl i to l ingestion when compared with glucose ingestion. However, the init ial dose of xyl i to l reaching the upper duodenum passed through the whole lower gastrointestinal system in 60-80 minutes resulting in diarrhoea in 50% of the subjects. The transient xylitol-induced