Initiation of motility in canine ileum by short chain fatty acids and inhibition by pharmacological agents

We have previously shown that short chain fatty acids (SCFA) stimulate motility in the canine ileum. Concentrations of SCFA in the ileum are normally low but would be expected to increase after coloileal reflux; thus, this phenomenon could have pathophysiological relevance. The present studies were designed to seek pharmacological means by which this response could be blocked. Four dogs were prepared with isolated, ileocolonic fistulae into which physiological concentrations of SCFA could be instilled so as to stimulate ileal motility. Pretreatment of the ileum with topical lidocaine abolished the response to luminal SCFA but general anaesthesia did not. Indomethacin stimulated ileal motility and prostacyclin abolished the ileal response to SCFA. Naloxone and a calcium channel blocker also negated the response to SCFA; blockage of muscarinic, adrenergic and 5-HT receptors did not. We conclude that the motor response to SCFA is probably a local neural reflex which is sensitive to local anaesthetics, opiates and the prostanoids.