Does the cholinergic system modulate gastrointestinal slow waves during less active phases of migrating myoelectric complex in healthy rams?

In six healthy rams possessing seven bipolar electrodes sewn onto the antrum and entire small intestine, the myoelectric activity recordings were performed in order to further elucidate the problem of possible contribution of cholinergic system in the control of slow wave amplitude and frequency. Experiments were carried out in fasted and non-fasted animals before and after feeding and intravenous cholinergic drug administration during phase 2b of the migrating myoelectric complex (MMC) (carbachol) and during phase 1-2a MMC (hexamethonium, atropine and pirenzepine). Antral slow wave amplitude was unaltered by cholinergic drugs with some exceptions. Small intestinal slow wave amplitude (principally examined in the jejunum) was also unchanged. Antral slow wave frequency was mostly unchanged with an increasing tendency but in some of experimental groups the results were statistically significant. Small intestinal slow wave frequency was diminished by carbachol and was partially increased (mostly increasing tendency) by the anticholinergic drugs. Thus, it is concluded that the cholinergic system can affect slow wave frequency in ovine antrum as well as in the small intestine in various phases of the MMC.