Cholinoceptive pontine reticular mechanisms cause state-dependent respiratory changes in the cat

This study tested the hypothesis that cholinoceptive regions of the medial pontine reticular formation (mPRF), long known to play a role in regulating the sleep cycle, can also causally alter the respiratory cycle. In 4 cats, sleep and wakefulness were polygraphically recorded while simultaneous measures were taken of rate of breathing, tidal volume, minute ventilation, respiratory cycle timing, and end-tidal CO2 concentration. Respiration during naturally occurring rapid eye movement (REM) sleep was compared to breathing during wakefulness and during the REM sleep-like state (D Carb) caused by mPRF microinjections of the cholinergic agonist carbachol. The results demonstrate for the first time that non-respiratory regions of the cholinoceptive mPRF can cause statistically significant state-dependent alterations in respiration.