State dependent modulation of breathing in rats during urethane anesthesia

Abstract

Breathing is an automatic process that is highly influenced by brain state, with abnormalities occurring more frequently during sleep. Although rodents are commonly used for respiratory neurobiology studies, they show irregular sleep patterns and cycles, which make studies of sleep‐dependent breathing challenging. The objective of this study was to determine if sleep‐like brain state alternations apparent under urethane anesthesia are correlated to changes in breathing parameters and respiratory muscle modulation, and to determine if they mimic changes occurring during natural sleep.Rats were anesthetized and respiratory parameters (rate, minute ventilation and EMG activity in diaphragm, genioglossus, abdominal and facial muscles) were recorded across different brain states as assessed by neocortical and hippocampal EEG. Results were compared with recordings in natural sleep. Our data show that brain state alternations under urethane anesthesia are correlated with changes in breathing rate, variability and respiratory muscle modulation and closely reproduce changes observed in natural sleep. Of particular interest is the present demonstration of prominent state dependent modulation of both genioglossus and abdominal muscle activity, which is a robust feature of sleep and sleep‐like brain state transitions.Supported by CIHR (JJG) and NSERC (CTD). SP is a Parker B. Francis fellow.