Impact of intermittent hypoxia on long-term facilitation of minute ventilation and heart rate variability in men and women: do sex differences exist?

• Published in: Journal of applied physiology (1985) 2008-06, Vol.104 (6), p.1625-1633
• Main Authors: Wadhwa, Harpreet, Gradinaru, Ciprian, Gates, Gregory J, Badr, M. Safwan, Mateika, Jason H
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Adult; Biological and medical sciences; Carbon Dioxide - administration & dosage; Female; Fundamental and applied biological sciences. Psychology; Gender differences; Heart - innervation; Heart - physiopathology; Heart Rate; Human exposure; Humans; Hypercapnia - physiopathology; Hypoxia; Hypoxia - physiopathology; Impact analysis; Lung - innervation; Lung - physiopathology; Male; Nervous system; Nitrogen - administration & dosage; Pulmonary Ventilation; Respiratory Mechanics; Sex Factors; Sympathetic Nervous System - physiopathology; Vagus Nerve - physiopathology
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01273.2007

Departments of 1 Physiology and 3 Internal Medicine, Wayne State University School of Medicine, Detroit; 4 Department of Biomedical Engineering, Wayne State University, Detroit; 2 John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; and 5 Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, New York Submitted 3 December 2007 ; accepted in final form 7 April 2008 Following exposure to intermittent hypoxia, respiratory motor activity and sympathetic nervous system activity may persist above baseline levels for over an hour. The present investigation was designed to determine whether sustained increases in minute ventilation and sympathovagal (S/V) balance, in addition to sustained depression of parasympathetic nervous system activity (PNSA), were greater in men compared with women following exposure to intermittent hypoxia. Fifteen healthy men and women matched for age, race, and body mass index were exposed to eight 4-min episodes of hypoxia during sustained hypercapnia followed by a 15-min end-recovery period. The magnitude of the increase in minute ventilation during the end-recovery period, compared with baseline, was similar in men and women (men, 1.52 ± 0.03; women, 1.57 ± 0.02 fraction of baseline; P < 0.0001). In contrast, depression of PNSA and increases in S/V balance were evident during the end-recovery period, compared with baseline, in men (PNSA, 0.66 ± 0.06 fraction of baseline, P < 0.0001; S/V balance, 2.8 ± 0.7 fraction of baseline, P < 0.03) but not in women (PNSA, 1.27 ± 0.19 fraction of baseline, P = 0.3; S/V balance, 1.8 ± 0.6 fraction of baseline, P = 0.2). We conclude that a sustained increase in minute ventilation, which is indicative of long-term facilitation, is evident in both men and women following exposure to intermittent hypoxia and that this response is independent of sex. In contrast, sustained alterations in autonomic nervous system activity were evident in men but not in women. carbon dioxide; parasympathetic nervous system; sympathovagal balance Address for reprint requests and other correspondence: J. H. Mateika, John D. Dingell VA Medical Center, 4646 John Rd. (11R), Rm. 4332, Detroit, MI, 48201 (e-mail: jmateika{at}med.wayne.edu )