A comparison of endothelial function in Caucasian and Chinese women before and after the menopause
Introduction
The apparent atheroprotective effect of female gender is most evident in the premenopausal years. Although women continue to have lower cardiovascular morbidity and mortality than age-matched males until late in the eighth decade [1], this gender difference begins to decline in the early postmenopausal period. In particular, arterial endothelial dysfunction, which is an early event in atherosclerosis, declines significantly in Caucasian females in the postmenopausal age group and at a greater rate than is observed in males [2], [3]. Endothelial dysfunction, together with a more atherogenic lipid and coagulation profile after the menopause, have been postulated as contributors to the higher cardiovascular morbidity and mortality in this age group, and focus placed on the probable atheroprotective effects of premenopausal female sex steroids such as oestrogen. Importantly, however, almost all such data have been collected from Caucasian populations. Whether similar observations can be demonstrated in the Chinese population (who contribute about one-quarter of the world’s population) and, more specifically, in Chinese women in the postmenopausal years has not previously been assessed.
Mainland Chinese (in particular, southern Chinese) have a much lower risk of coronary artery disease than ‘westernised’ Caucasian populations. We have previously shown that the decline in endothelial function with increasing age observed in healthy Caucasian populations does not appear to occur in southern Chinese subjects—a finding independent of cholesterol, blood pressure and vessel size [4]. In this study, we specifically examine the effect of menopausal status on endothelial function in healthy southern Chinese females from a village in Southern China as compared with age-matched Caucasian females from Sydney, a typical industrialised city in Australia.
Section snippets
Subjects
We studied 40 females (20 Chinese and 20 Caucasian subjects) aged 20–66 years of age; none had a history of hyperlipidaemia, hypertension, family history of premature vascular disease or exposure to active or passive smoking. None of the postmenopausal females had had menses for at least 2 years, and none were taking hormone replacement therapy. All women were recruited from community volunteers, all gave consent and historical details in their native language, and the study was approved by our
Results
Baseline characteristics for each group are outlined in Table 1. Endothelium-dependent dilatation was significantly reduced in Caucasian women after the menopause compared with those who were premenopausal (8.4±2.7% versus 2.7±2.9%; P<0.001), but was not different in the two groups of Chinese women (9.8±3.3% versus 8.3±1.6%, for pre- and postmenopausal Chinese females respectively; P=0.22) (Fig. 1). Similarly, endothelium-independent responses assessed with sublingual GTN were significantly
Discussion
This study documents a decline in vascular reactivity in Caucasian but not Chinese females, in the postmenopausal period. This is an important observation, as many studies (predominantly involving westernised Caucasian female populations) [2], [10], [11] have suggested that women as a group experience a decline in endothelial function in the postmenopausal years and that hormone replacement therapy may ‘prevent’ or ‘ameliorate’ such changes in older females [3], [12], as well as decreasing
Acknowledgements
The authors would like to thank Acuson and the US–China Industrial Exchange (Chindex) for the provision of ultrasound equipment and technical support in Shek Kei village, and Dr J.Z. Feng and the staff from The Guangdong Provincial Cardiovascular Institute, Guangzhou, People’s Republic of China for their support and expertise.
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