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(Stroke. 2004;35:e71.)
© 2004 American Heart Association, Inc.

Letters to the Editor

Smoking, Estrogen, and Membrane Microviscosity in Women

Division of Cardiology, Department of Medicine, Wakayama Medical University, Wakayama, Japan

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

We read with great interest the recent article by Dr. Kurth et al¹ dealing with the relationship between smoking and hemorrhagic stroke in women. The results of their prospective study demonstrated that the risk of total hemorrhagic stroke, such as intracerebral hemorrhage and subarachnoid hemorrhage, was increased in women who are current cigarette smokers. The authors proposed that smoking may cause structural damage to the arterial wall and be a risk factor for both ischemic and hemorrhagic stroke in women.

Numerous studies have shown that estrogen may protect the brain from experimental stroke, such as global brain ischemia and subarachnoidal hemorrhage.² One of the mechanisms underlying the protective effect of estrogen may be the enhancement of nitric oxide (NO) production. There is evidence showing that vascular endothelial function is markedly influenced by estrogen, and is improved by hormone replacement therapy in postmenopausal women.³ In an in vitro study presented earlier, we demonstrated that 17 ß-estradiol increased membrane fluidity (a reciprocal value of membrane microviscosity) of erythrocytes and improved the rigidity of cell membranes in postmenopausal women via the NO- and cGMP-dependent mechanisms.⁴ In a separate series of experiments, we showed that hormone replacement therapy restored the membrane microviscosity in elderly women with a concomitant increase in plasma NO metabolite level.⁵ These findings suggest that, because abnormalities in membrane microviscosity could cause a disturbance in rheological behavior and microcirculation, estrogen-deficiency might be involved in the pathogenesis of vascular complications in women. In this context, it can be speculated . . . [Full Text of this Article]

Tobias Kurth, MD, ScD Julie E. Buring, ScD

Division of Preventive Medicine, Brigham and Women’s Hospital, Boston, Massachusetts