Acute reverse microdialysis (MD) of atropine into the pontine respiratory group (PRG) of goats at night has no affect on breathing, but does tend to increase NREM and REM sleep

Abstract

Acetylcholine is an important neurotransmitter in the PRG (Respir. Physiol. Neurobiol. 2004 Nov 15;143(2‐3):235‐49). Tonic pontine influences may have increased importance during sleep to stabilize and prevent large fluctuations in breathing. Abnormalities in this tonic facilitation, such as attenuation of cholinergic modulation (Respir. Physiol. Neurobiol. 131:135‐144, 2002.), may contribute to sleep‐disordered breathing. Accordingly, we chronically implanted microtubules into the PRG of 7 goats to assess the response of MD of atropine (50mM) into the PRG at night. MD of atropine at night did not have a significant effect on pulmonary ventilation (VI), breathing frequency, or tidal volume compared to MD of mock cerebral spinal fluid (mCSF). However, a normal state‐dependent respiratory depression was observed, where VI during REM < VI during NREM < VI during wakefulness. The percent of NREM and REM sleep tended to increase from the first night of ipsilateral MD, to the second night of contralateral MD, and to the third night of bilateral MD. We conclude that MD of atropine into the PRG at night does not affect breathing, but does tend to increase both NREM and REM sleep. Supported by the Department of Veterans Affairs and NIH 25739.