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Peak expiratory nitric oxide differences in men and women: relation to the menstrual cycle
S A Kharitonov1, R B Logan-Sinclair, C M Busset
1Department of Paediatrics, Royal Brompton National Heart and Lung Hospital, London.
Objective:
To develop a method to measure end expiratory nitric oxide concentration and to use it to determine whether there are sex related differences between healthy men and women.
Design:
Modification of commercially available chemiluminescent analyser to allow endogenous nitric oxide (endothelium derived relaxing factor) to be measured in a single slow forced vital capacity manoeuvre with evaluation of between and within subject variability. Serial measurements in women throughout the menstrual cycle.
Setting:
Specialist referral hospital.
Subjects:
59 healthy volunteers (40 men and 19 women).
Results:
Mean (SD) peak expiratory concentrations of nitric oxide in men (75 (20) ppb (parts per billion)), and women (70 (37) ppb (first measurement)) were > 5 times those previously recorded. In women concentrations at midcycle (150(39) ppb) were significantly higher (mean difference 94.9(41), P < 0.001) than during menstruation (59(25) ppb).
Conclusion:
Nitric oxide production (endothelium derived relaxing factor activity) is influenced by cyclical hormonal changes in women. There was an increase of more than 100% at mid cycle. This may be pertinent to the lower risk of cardiovascular disease in premenopausal women.