Effects of NMDA receptor antagonists on visceromotor reflexes and on intestinal motility, in vivo

Abstract

Antagonists of NMDA receptors can inhibit both the transmission of pain signals from the intestine and enteric reflexes. However, it is unknown whether doses of the NMDA antagonist, ketamine, that are used in anaesthetic mixtures suppress motility reflexes and visceromotor responses (VMRs). In fact, whether intestinal motility is affected by NMDA receptor blockers in vivo has been little investigated. We studied the effects of ketamine and memantine, administered intravenously or intrathecally. Rats were maintained under α-chloralose plus xylazine or pentobarbitone anaesthesia; VMR and jejunal motility were measured. Under α-chloralose/xylazine anaesthesia, i.v. ketamine inhibited VMRs at 6 ..