Blood pressure and water regulation: understanding sex hormone effects within and between men and women

Abstract

Cardiovascular disease remains the leading cause of death for both men and women. Hypertension is less prevalent in young women compared with young men, but menopausal women are at greater risk for hypertension compared with men of similar age. Despite these risks, women do not consistently receive first line treatment for the early stages of hypertension, and the greater morbidity in menopause reflects this neglect. This review focuses on ovarian hormone effects on the cardiovascular and water regulatory systems that are associated with blood pressure control in women. The study of ovarian hormones within young women is complex because these hormones fluctuate across the menstrual cycle, and these fluctuations can complicate conclusions regarding sex differences. To better isolate the effects of oestrogen and progesterone on the cardiovascular and water regulation systems, we developed a model to transiently suppress reproductive function followed by controlled hormone administration. Sex differences in autonomic regulation of blood pressure appear related to ovarian hormone exposure, and these hormonal differences contribute to sex differences in hypertension and orthostatic tolerance. Oestrogen and progesterone exposure are also associated with plasma volume expansion, and a leftward shift in the osmotic operating point for body fluid regulation. In young, healthy women, the shift in osmoregulation appears to have only a minor effect on overall body water balance. Our overarching conclusion is that ovarian hormone exposure is the important underlying factor contributing to differences in blood pressure and water regulation between women and men, and within women throughout the lifespan.

Effects of a 24-h naproxen dose on hydration and electrolyte measures during moderate-intensity cycling in the heat

“…Resting plasma vasopressin varies in females depending on menstrual phase. Vasopressin is significantly lower than males during the early follicular phase, but not during the luteal phase (Wenner and Stachenfeld 2012). These variances may help explain why we found differences in Fvol between genders.…”

“…Another mechanism for thirst stimulation is an increase in vasopressin from NSAIDs (Cheng and Harris 2005). Vasopressin is typically upregulated during dehydration to restore plasma volume, and vasopressin increase is positively and linearly associated with thirst (Wenner and Stachenfeld 2012). Despite our participants being euhydrated, if naproxen stimulated vasopressin it could have increased their fluid intake.…”

“…BP is generally higher for males than females (Christou et al 2005), which is attributed to physical differences, hormones, and vascular responsiveness (Wenner and Stachenfeld 2012 …”

Evidence for a Prognostic Role of Orthostatic Hypertension on Survival in a Very Old Institutionalized Population

“…As reported in literature, BP reactivity secondary to sympathetic modifications increases with age in women. 17 This could explain the higher prevalence of women in the OHyperT group.…”

Sustained increases in blood pressure elicited by prolonged face cooling in humans

“…Notably, we are underpowered to conduct a formal analysis between males and females. Furthermore, menstrual cycle hormones modulate the mechanisms underlying blood pressure regulation (24). Thus, the hemodynamic responses, and the underlying mechanisms, elicited by face cooling might be modulated by menstrual cycle phase.…”