Background/Aims: The role of nitric oxide (NO) in general anesthetic drug action is controversial. The present
study was carried out to determine the role of NO in the loss of righting reflex induced by injectable sedative and
Methods: Under isoflurane anesthesia, male NIH Swiss mice received an intracerebroventricular microinjection of the NOdonor
3-morpholinosydnoimine (SIN-1) 30 min prior to an i.p. injection of chloral hydrate, sodium barbital, midazolam or
ketamine/xylazine. Mice were monitored for onset and duration of loss of righting reflex (LORR).
Results: Pretreatment with SIN-1 reduced the mean duration of LORR induced by chloral hydrate, sodium barbital and
midazolam but not ketamine/xylazine. Pretreatment with SIN-1 had no effect on the mean latency to LORR.
Conclusion: It is concluded that there may be a differential involvement of NO in the LORR response, depending upon
whether the primary drug action is through GABAA or NMDA receptors.