MedWire News: Changes in lung function occur over the course of the menstrual cycle in both asthmatic and nonasthmatic women, but through different mechanisms, research shows.
“Angiogenesis is a defining pathologic feature of airway remodeling and contributes to asthma severity,” write Samar Farha (Cleveland Clinic, Cleveland, Ohio, USA) and team in the American Journal of Respiratory and Critical Care Medicine.
They explain: “Women experience changes in asthma control over the menstrual cycle, a time when vessels routinely form and regress under the control of angiogenic factors. One vital function modulated over the menstrual cycle in healthy women is gas transfer, and this has been related to angiogenesis and cyclic expansion of the pulmonary vascular bed.”
To investigate whether changes in gas transfer and the pulmonary vascular bed occur in asthmatic women over the course of the menstrual cycle, and whether such changes are linked to worsening airflow obstruction, the team studied 13 nonsmoking women with asthma and 10 healthy women without the respiratory condition who were aged between 29 and 33 years. All the women had regular menstrual cycles.
Women with asthma were similar to healthy women in terms of age, height, race, and use of contraceptives.
Over a 4–5 week period, all the women underwent weekly spirometry tests to assess lung function, as well as weekly measurements of gas transfer, nitric oxide, hemoglobin, factors affecting hemoglobin binding affinity, and proangiogenic factors.
The researchers found that in all the women, FEV1 and gas transfer varied over the menstrual cycle, with peak levels at the end of the luteal phase through the start of menstruation and gradually declined thereafter.
In contrast to healthy women, changes in lung diffusing capacity (DLCO) in asthmatic women were associated with changes in membrane diffusing capacity.
In further contrast to healthy women, circulating proangiogenic progenitor cells were unrelated to DLCO in women with asthma.
However, DLCO did not differ overall between the two groups.
Farha and colleagues conclude: “The menstrual cycle is one of the most important biological rhythms that govern physiological processes of living beings.
“Here, airflow and gas transfer are shown to be among the many vital functions modulated over the menstrual cycle, but the cyclic respiratory changes occur by very different physiologic mechanisms in women with asthma as compared with healthy women.”
They add: “These findings begin to provide insight into understanding features of asthma unique to women, including perhaps the much greater prevalence of difficult-to-control and severe asthma among women and the phenomenon of perimenstrual asthma exacerbations.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009
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