The effect of intrathecal medetomidine on small bowel transit in the rat.

BACKGROUND AND OBJECTIVE

Gastrointestinal motility is influenced by abdominal trauma, laparotomy and particularly by intestinal ischaemia. The reflex inhibition of gastrointestinal motility is mediated mainly by the sympathetic nervous system. There are reports on the effects of systemically applied alpha2-adrenoceptor agonists on gastric emptying and recovery of bowel motility, but the effect of spinally applied alpha2-adrenoceptor agonists on intestinal motility has not been studied. The aim of this study was to investigate the effects of intrathecal medetomidine on gastrointestinal transit in rats after transient intestinal ischaemia.

METHODS

Forty rats were randomly assigned to four groups of 10 each. Intrathecal catheter insertion and laparotomy were performed on each rat. Saline (10 microL) was injected intrathecally in Groups A and B. Medetomidine (10 microg in 10 microL) was injected intrathecally in Groups C and D. Intestinal ischaemia was induced in Groups B and D. Gastrointestinal transit was determined by measuring the length that a standardized marker meal of activated charcoal had travelled. Intrathecal medetomidine was compared to intrathecal saline in their effect on intestinal motility after 30 min period of bowel ischaemia.

RESULTS

Laparotomy and intestinal ischaemia slowed gastrointestinal transit. Intrathecal medetomidine accelerated transit in both ischaemia and non-ischaemia groups.

CONCLUSION

Intrathecal medetomidine markedly accelerated small intestinal transit and may also hasten the recovery from post-ischaemic paralytic ileus.