Effect of rabbit antimotilin serum on myoelectric activity and plasma motilin concentration in fasting dog

It is known that a cyclic increase in plasma motilin concentration occurs during the interdigestive state of dog and the increase coincides with migrating myoelectric complexes (MMCs) of the antrum as well as proximal duodenum. The purpose of the present study is to determine the role of endogenous motilin in the occurrence of MMCs in 10 dogs prepared with a gastric cannula and platinum monopolar electrodes in the gastric antrum, duodenum, jejunum, and ileum. After recording at least two consecutive cycles of MMCs from the proximal duodenum, each dog received an intravenous infusion of highly specific rabbit antimotilin sera in varying doses ranging from 3.5 to 15 ml for a period of 60 or 90 min. During the motility recording period ranging from 6 to 30 h following the administration of the antimotilin serum, several changes in the motility were observed. 1) The occurrence of MMCs in the antrum, duodenum, jejunum, and ileum was temporarily interrupted for varying periods depending on the individual dog studied and the amount of antiserum administered. When the higher dose of antimotilin was administered, a more profound and prolonged inhibition occurred. 2) Phase I activity rarely occurred. Instead, a phase II-like activity continued throughout the recording period. 3) MMCs in the jejunum or ileum occurred at irregular intervals without aboral propagation of MMCs from the duodenum or jejunum. 4) The plasma motilin concentration decreased to levels lower than that observed during phase I of the duodenum and exhibited no cyclic increase until the MMCs reappeared in the proximal duodenum.(ABSTRACT TRUNCATED AT 250 WORDS)