RHYTHMIC OSCILLATING COMPLEX - CHARACTERIZATION, INDUCTION, AND RELATIONSHIP TO MMC IN CHICKENS

Migrating myoelectrical complexes (MMCs) and rhythmic oscillating comp lexes (ROCs) have been investigated in chickens prepared for electromy ography. Animals were chronically implanted with electrodes in stomach , duodenum, jejunum, ileum, ceca, and rectum. MMCs showing phases I-II I were found in the jejunum and ileum both in fed and fasted states. R epetitive spike bursts were recorded in the duodenum (0.5-1/h), disrup ting the gastroduodenal coordination and preceding a phase III in the jejunum. ROCs appeared spontaneously in fasted animals and in 75% of t he recordings during the dark period. Four consecutive intestinal myoe lectrical patterns have been described during a ROC. Briefly, they con sisted in series of high-speed propagated aborad contractions of great amplitude that progressively changed into others of orad direction. I n relation to the MMC, the ROC pattern appeared just after a phase III reached the distal ileum, and a pattern of duodenal repetitive spike bursts, followed by a migrating phase III in the jejunum, started at t he duodenum after a ROC. No myoelectrical changes were recorded in cec orectal activity during ROC. Vagotomized animals showed the ROC patter n. Neither apomorphine (5-100 mu g/kg iv) nor cholecystokinin (10(-9) mol/kg iv) induced ROCs. Naloxone (5 x 10(-7) mol/kg iv) and atropine (0.1 mg/kg iv) induced isolated orad contractions. Myoelectrical and f unctional similarities can be found between retrograde giant contracti ons, described in mammals, and ROCs. However, they differ in their ori gin and mechanism of induction.