Abstract
We investigated the hypothesis that ketamine-induced respiratory depression might be mediated through the opiate system that can be eliminated by naloxone. The steady-state respiratory responses to iv. ketamine (2mg•ml-1•kg-1) and their antagonism by naloxone (0.4mg•ml-1•kg-1) were studied in anesthetized, paralyzed, vagotomized, and artificially ventilated cats. We found that ketamine depressed central respiratory output, assessed from the phrenic nerve electroneurogram, leading to apneustic breathing, which was not antagonized by naloxone. The apneustic respiratory depression by ketamine was thus mediated through mechanism other than the opiate system.
