Functional Genomics of Sleep and Circadian Rhythm: Selected Contribution: Genioglossus muscle activity at rest and in response to brief hypoxia in healthy men and women

• Published in: Journal of applied physiology (1985) Vol. 92; no. 1; p. 410
• Main Authors: Jordan, A. S, Catcheside, P. G, O'Donoghue, F. J, Saunders, N. A, McEvoy, R. D
• Format: Journal Article
• Language: English
• Published: Am Physiological Soc 01.01.2002
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00461.2001

1  Sleep Disorders Unit, Repatriation General Hospital, Daw Park 5041; 2  Department of Physiology, University of Adelaide, Adelaide 5005; and 3  School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia 10.1152/japplphysiol.00461.2001. Obstructive sleep apnea (OSA) is more common in men than in women for reasons that are not clearly understood. An underlying difference between men and women in the respiratory-related neural control of upper airway dilator muscles has been suggested as a possible reason for the gender difference. We have compared three aspects of upper airway dilator muscle function in healthy men and women: 1 ) resting inspiratory genioglossus electromyogram (EMGgg) activity, 2 ) the respiratory EMGgg "afterdischarge" after a brief hypoxic stimulus, and 3 ) the relationship between the EMGgg and pharyngeal airway pressure. Inspired minute ventilation ( I ), epiglottic pressure (P epi ), and EMGgg and diaphragm EMG (EMGdi) activity were measured in 24 subjects (12 men, 12 women in the luteal menstrual phase) and were compared between genders while lying supine awake. Every 7-8 min over 2 h, subjects were exposed to 45-s periods of isocapnic hypoxia (9% O 2 in N 2 ) that were abruptly terminated with one breath of 100% O 2 . The relationship between P epi and EMGgg activity was also compared between genders. The results of 117 trials with satisfactory end-tidal P CO 2 control and no sighs or swallows are reported. There was no gender difference in the resting level of peak inspiratory EMGgg [3.7 ± 0.8 (women) vs. 3.2 ± 0.6% maximal activity (men)]. Repeated-measures ANOVA showed no gender or gender-by-time interaction effect between men and women in I or EMGgg or EMGdi activity during or after the hypoxic stimulus. The relationship between P epi and EMGgg was not different between men (slope 0.63   ± 0.20) and women (slope 0.69 ± 0.33). These results do not support the hypothesis that the higher prevalence of OSA in men is related to an underlying gender difference in respiratory neural control of upper airway dilator muscles. upper airway muscle control; ventilatory afterdischarge; obstructive sleep apnea; gender