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Ten hypoxic episodes induce similar ventilatory long‐term facilitation in Lewis and Brown Norway rats
Author(s) -
Dahlberg Jenny M,
Mahamed Safraaz,
Molter Christine M,
Wilkerson Julia ER,
Mitchell Gordon S
Publication year - 2006
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.20.4.a372-c
Subject(s) - intermittent hypoxia , hypoxia (environmental) , respiratory system , ventilation (architecture) , tidal volume , carotid body , hypoxic ventilatory response , medicine , endocrinology , respiratory minute volume , biology , anesthesia , chemistry , stimulation , oxygen , organic chemistry , mechanical engineering , obstructive sleep apnea , engineering
Acute intermittent hypoxia (3 to 5 episodes) elicits a form of respiratory plasticity known as long‐term facilitation (LTF), a prolonged increase in phrenic, hypoglossal, and/or ventilatory output after the final hypoxic episode. Preconditioning rats for 7 days with daily acute intermittent hypoxia (dAIH; 10, 5‐min episodes, 11±0.5% O2) enhances LTF in Brown Norway rats, an example of respiratory metaplasticity (Wilkerson et al., FASEB J. 2005). To begin exploring cellular/synaptic mechanisms of enhanced LTF following dAIH, we performed experiments to determine the magnitude of ventilatory LTF (vLTF) following the first day of dAIH, and harvested the tissues for protein and mRNA analyses. Here we report the ventilatory data for Lewis and Brown Norway rats, two inbred rat strains with differential phrenic LTF expression. Ventilation was measured in adult, male Lewis (Colony 202B, n=31) and Brown Norway (Colony 217, n=32) rats via whole body plethysmography before, during and 60 min following 10, 5‐min hypoxic episodes (10.5%; ie. 1 day of dAIH) or in normoxic time controls. Significant vLTF was observed in both rat strains relative to normoxic time controls at 25–30 (p<0.05), but not 55–60 min post‐hypoxia; vLTF was expressed primarily as increased tidal volume with variable frequency effects. Strain differences in vLTF were not observed. Thus, one day of dAIH elicits similar vLTF in the two inbred rat strains, although the magnitude and duration of this effect is limited. Supported by NIH HL65383, HL89209, and HL69064.