Chronic intermittent hypoxia enhances ventilatory long-term facilitation in awake rats.
This study examined the effect of chronic intermittent hypoxia (CIH: 5 min 11-12% O2/5 min air, 12 h/night, 7 nights) on ventilatory long-term facilitation (LTF) and determined the persistence period of this CIH effect in awake rats. LTF, elicited by 5 or 10 episodes of 5 min 12% O2, was measured four times in the same Sprague-Dawley rats by plethysmography, before and 8 h, 3 days, and 7 days after CIH treatment. Resting ventilation was unchanged after CIH. Five episodes of 12% O2 did not initially elicit LTF but elicited LTF (23.5 +/- 1.4% above baseline) 8 h after CIH, which partially remained at 3 days (11.4 +/- 2.2%, P < 0.05) and disappeared at 7 days. Ten episodes initially elicited LTF (17.7 +/- 1.1%, 45-min duration) and elicited an enhanced LTF (29.1 +/- 1.5%, 75 min) 8 h after CIH. These results demonstrated that CIH enhanced ventilatory LTF in conscious, freely behaving rats in two ways: 1) a previously ineffective protocol induced LTF; and 2) LTF magnitude was increased and LTF duration prolonged, and this CIH effect on LTF persisted for at least 3 days.
McGuire
Michelle
M
Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Ave., Boston, MA 02115, USA.
Zhang
Yi
Y
White
David P
DP
Ling
Liming
L
D000280:Administration, Inhalation; D000818:Animals; D002908:Chronic Disease; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D015656:Respiratory Mechanics; D013997:Time Factors
D010100:Oxygen