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Morphine suppresses augmented breaths independently of changes in hypoxic chemosensitivity or central respiratory drive
Author(s) -
Bell Harold James,
Kehoe Valerie,
Haouzi Philippe A
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.799.31
Subject(s) - morphine , hypoxia (environmental) , opioid , respiratory system , anesthesia , medicine , ventilation (architecture) , control of respiration , respiration , tidal volume , chemistry , oxygen , receptor , mechanical engineering , organic chemistry , engineering , anatomy
The link between opioid therapy and central sleep disordered breathing (SDB) is not known. Since augmented breaths (ABs) are known to destabilize breathing, we sought to determine whether opioid therapy increases the prevalence of ABs, and thereby exacerbates SBD. We therefore monitored unanesthetized, unrestrained male rats in room air RA and hypoxia (10% O 2 ), before and after a single dose of morphine (5 mg/kg s.c.). Morphine suppressed ABs from 2.0 ± 0.0 in a 5 min observation window, to nil (0.0 ± 0.0). The normal hypoxia‐induced facilitation of ABs was suppressed by morphine (14.8 ± 4.8 vs. 6.0 ± 2.6 ABs in 5 min). VE was increased slightly after morphine in RA (82 ± 6 vs. 115 ± 21 ml/min/100g). During hypoxia VE was unchanged by morphine administration (160 ± 16 vs. 160 ± 17 ml/min/100g), indicating that hypoxic chemosensitivity was unaffected at this dose. Breathing frequency was significantly depressed by morphine but only during exposure to hypoxia (170 ± 23 vs. 127 ± 10 bpm). Nevertheless, the suppression of ABs by morphine was 2.5 fold greater than the observed decrease in breathing frequency. Our results suggest that morphine does not exacerbate central SDB via an increased prevalence of ABs. Rather, morphine suppresses ABs, even at a dose that does not depress either hypoxic chemosensitivity or central respiratory drive.