Antral myoelectric activity in sheep: the effect of feeding and anti- cholinergic drug administration during various. phases of migrating myo- eiectric complex... *

Abstract

In six adult rams, chronic experiments were performed to assess the role of fasting, feeding, phase of migrating myoelectric complex (MMC) and anticholinergic drugs in antral myoelectric activity. Accordingly, animals underwent surgical implantation of five bipolar electrodes in to the antrum duodenum and jejunum for continuous myoelectric activity recordings. Normal control spike burst amplitude in non-fasted sheep during phase 2b MMC and during feeding was 103±19 vs. 155±10[iV (p<0.01) whereas spike burst duration was 2.8±0.12 vs. 3.0±0.09 s (N.S), respectively. Feeding increased significantly the percentage of antral spike burst mean amplitudes while slow intravenous administration of graded doses ofatropine and pirenzepine as well as of hexamethonium, alone and in combinations, usually depressed the antral spike bursts. Complete inhibition was observed occasionally. In non-fasted sheep equivalent values obtained during phase 2b MMC were 84±8 71 ±3, 74±3 (control) and 18±6, 17±2, 28±2 (p<0.001, moderate drug doses) respectively. These change were more pronounced during feeding and when the drugs were given during phase 2b or phase 3 of MMC. Further increase of the cholinergic blocking drug doses evoked relatively lower inhibition. It is concludedthat the cholinergic system is important in the control of antral myoelectric activity in sheep. Moreover, it appears that during various MMC phases, different mechanisms can be activated.