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Combined Effects of Intermittent Hyperoxia and Intermittent Hypercapnic Hypoxia on Respiratory Control
Author(s) -
Millstrom Alexandra,
Kim Song,
Asklof Kendra,
McDonough Amy,
Bavis Ryan
Publication year - 2015
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.29.1_supplement.659.16
Subject(s) - hyperoxia , intermittent hypoxia , carotid body , hypoxia (environmental) , hypoxic ventilatory response , hypercapnia , anesthesia , plethysmograph , medicine , control of respiration , respiratory system , respiration , ventilation (architecture) , lung , endocrinology , chemistry , oxygen , anatomy , electrophysiology , mechanical engineering , organic chemistry , obstructive sleep apnea , engineering
We previously observed that chronic intermittent hyperoxia attenuates the hypoxic ventilatory response (HVR) in neonatal rats. In clinical situations, however, intermittent hyperoxia alternates with bouts of hypercapnic hypoxia. In the present study, we exposed rats from birth through 14 days of age to one of three treatments: control (21% O 2 /0% CO 2 ), intermittent hypercapnic hypoxia (10% O 2 /6% CO 2 , 5 episodes h ‐1 ; I 21/10 ), or intermittent hyperoxia + hypercapnic hypoxia (30% O 2 /0% CO 2 to 10% O 2 /6% CO 2 , 5 episodes h ‐1 ; I 30/10 ). I 30/10 rats exhibited slightly greater baseline ventilation than controls (measured by head‐body plethysmography) at P14, but this corresponded to a greater resting metabolic rate (in both I 30/10 and I 21/10 vs. controls). Although I 21/10 and I 30/10 treatments reduced single‐unit carotid chemoafferent responses to hypoxia (measured in vitro ), the HVR was not different from that of control rats in either of these groups. Similarly, I 21/10 and I 30/10 treatments did not alter the hypercapnic ventilatory response. I 21/10 and I 30/10 rats had larger mass‐specific dry lung weight compared to controls, while continuous hyperoxia (60% O 2 ) decreased lung size. Our results suggest that intermittent hypercapnic hypoxia counteracts the effects of intermittent hyperoxia, either by presenting an opposing stimulus (e.g., carotid body activation vs. inhibition) or by eliciting a more prominent plastic response.