Impaired Cardiovagal Baroreflex in Black Women with AE‐PCOS

Abstract

Polycystic ovary syndrome (PCOS) is a reproductive endocrine disorder affecting 1 in 10 women of reproductive age. Approximately 75% of PCOS is characterized by androgen excess (AE-PCOS), and AE-PCOS is associated with cardiovascular disease (CVD), high blood pressure (BP), insulin resistance, and obesity. CVD and hypertension affect black women more severely than white women and these differences may be evident in AE-PCOS, although mechanisms for these racial differences within PCOS have not been investigated. A key component of BP regulation is the autonomic nervous system. We hypothesized that black AE-PCOS women have lower cardiovagal baroreflex sensitivity (BRS) than white AE-PCOS women. We tested 6 AE-PCOS women (n=2 black, age 28 ± 5 yr; BMI 38 ± 3 kg/m2; mean SBP 156 ± 16 mm Hg and n=4 white, age 26 ± 5 yr; BMI 35 ± 7 kg/m2; SBP 135 ± 9 mm Hg). Insulin resistance was similar between groups as determined from an oral glucose tolerance test: AUC for insulin 27685 ± 8547 IU and 25081 ± 13255 IU for black and white subjects, respectively). We determined cardiovagal BRS at rest in the supine position (3 min) and during a Modified Oxford protocol, where subjects underwent IV infusions of sodium nitroprusside (1 min) and phenylephrine (1 min), respectively. We applied linear regression to the beat-to-beat SBP time series as a function of R-R interval in response to phenylephrine to determine cardiovagal BRS. While our sample size is still small, the BRS slopes for individual black women were consistently lower compared to the white subjects. On average, BRS in black AE-PCOS women (0.012 ± 0.000 sec/mm Hg) was 70% lower than white AE-PCOS women (0.025 ± 0.018 sec/mm Hg). The preliminary findings of this study indicate higher SBP in black women, and this was associated with impaired autonomic function compared to white women with AE-PCOS. More studies will be done in order to confirm these findings and to examine mechanisms for this potentially impaired autonomic function in black women with AE-PCOS. Racism and discrimination are important social factors that contribute to impaired BP regulation, and AE-PCOS may exacerbate this condition in black women; in combination, these factors may explain the higher risk for CVD that is known to disproportionately affect black women. There have been studies addressing BP regulation in black men, but few studies have addressed BP regulation in black women or racial differences within women. Our data show that race is an important consideration for research and treatment in women with AE-PCOS. This is the first study to demonstrate that autonomic function may contribute to impaired BP regulation in black women with AE-PCOS.