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The magnitude of ventilatory long term facilitation and the hypoxic ventilatory response is affected by time of day
Author(s) -
Carney L M,
Anthouard M N,
Lee D S,
Badr M S,
Mateika J H
Publication year - 2009
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.23.1_supplement.621.18
Subject(s) - hypoxic ventilatory response , intermittent hypoxia , morning , evening , medicine , hypoxia (environmental) , anesthesia , apnea , respiratory system , obstructive sleep apnea , chemistry , oxygen , physics , organic chemistry , astronomy
Purpose To determine if the magnitude of ventilatory long term facilitation (vLTF) and the hypoxic ventilatory response (ΔV E /ΔSaO 2 ‐ HVR) following exposure to intermittent hypoxia (IH) is affected by time of day. Methods 7 male subjects with obstructive sleep apnea were exposed to IH daily for 11 days. The protocol included 12 4‐minute episodes of hypoxia (P ET O 2 ‐ 50 mmHg, P ET CO 2 ‐ 3 mmHg above baseline) followed by a 30 minute end‐recovery period. On days 1 and 11 IH was applied in the evening (PM), and in the morning (AM) on days 2‐10. Before and after daily exposure to IH the HVR was measured. Results On Day 1 & 11 (PM) and Day 2 & 10 (AM), V E and the HVR were significantly greater after IH compared to baseline, consistent with our other findings (data not shown ‐ see abstracts from Gerst et al. and Lee et al.). However, vLTF was less (p = 0.004) and the HVR was greater (p = 0.01) during the AM compared to the PM studies before (Days 1 & 2) and after (Days 10 vs. 11) 11 days of IH. Additionally, the vLTF and HVR responses after IH were greater on Days 10 & 11 compared to Days 1 & 2 (vLTF ‐ p = 0.01; HVR ‐ p = 0.05). Conclusions The magnitude of vLTF is less and the HVR is greater after AM compared to PM exposure to IH. This relationship persists following chronic IH. Funding NIH (HL‐085537)