Estradiol- and progesterone-related increases in the renin-aldosterone system: studies during ovarian stimulation and early pregnancy

The effect of hormonal contraceptive therapy on clinical laboratory parameters: a literature review

Hormonal contraceptives (HC) are widely used among women in reproductive ages. In this review, the effects of HCs on 91 routine chemistry tests, metabolic tests, and tests for liver function, hemostatic system, renal function, hormones, vitamins and minerals were evaluated. Test parameters were differently affected by the dosage, duration, composition of HCs and route of administration. Most studies concerned the effects of combined oral contraceptives (COC) on the metabolic, hemostatic and (sex) steroids test results. Although the majority of the effects were minor, a major increase was seen in angiotensinogen levels (90-375 %) and the concentrations of the binding proteins (SHBG [∼200 %], CBG [∼100 %], TBG [∼90 %], VDBP [∼30 %], and IGFBPs [∼40 %]). Also, there were significant changes in levels of their bound molecules (testosterone, T3, T4, cortisol, vitamin D, IGF1 and GH). Data about the effects of all kinds of HCs on all test results are limited and sometimes inconclusive due to the large variety in HC, administration routes and dosages. Still, it can be concluded that HC use in women mainly stimulates the liver production of binding proteins. All biochemical test results of women using HC should be assessed carefully and unexpected test results should be further evaluated for both methodological and pre-analytical reasons. As HCs change over time, future studies are needed to learn more about the effects of other types, routes and combinations of HCs on clinical chemistry tests.

Assisted reproductive technology: what are the cardiovascular risks for women?

INTRODUCTION

Infertility affects 15% of women of reproductive age in the United States. The use of assisted reproductive technology (ART) has been rising globally, as well as a growing recognition of reproductive factors that increase risk for cardiovascular disease (CVD).

AREAS COVERED

Women with infertility who use ART are more likely to have established CVD risk factors, such as obesity, dyslipidemia, hypertension, and diabetes. They are also more likely to experience adverse pregnancy outcomes, which are associated with both peripartum and long-term cardiovascular complications. ART may lead to increased cardiometabolic demands due to ovarian stimulation, pregnancy itself, and higher rates of multifetal gestation. Preeclampsia risk appears greater with frozen rather than fresh embryo transfers.

EXPERT OPINION

The use of ART and its association with long term CVD has not been well-studied. Future prospective and mechanistic studies investigating the association of ART and CVD risk may help determine causality. Nevertheless, CVD risk screening is critical pre-pregnancy and during pregnancy to reduce pregnancy complications that elevate future CVD risk. This also offers a window of opportunity to connect patients to longitudinal care for early management of cardiometabolic risk profile and initiation of preventive lifestyle and pharmacotherapy interventions tailored toward patient-specific risk factors.

History of infertility and pregnancy outcomes in Project Viva: a prospective study

Background

Infertility has been associated with the risk of adverse pregnancy outcomes. It is not clear whether infertility and underlying causes of infertility or the use of medically assisted reproduction (MAR) therapies are responsible for the observed associations. In this study, we aimed to evaluate the association of history of infertility with pregnancy outcomes and identify whether the associations, if present, differed by subgroups defined by the use of MAR.

Methods

Prospective study of 2201 pregnant women from the Boston-area Project Viva cohort. The exposure was history of infertility based on self-reported time to pregnancy ≥12 mo (or ≥ 6 mo if ≥35 y) or use of MAR; a diagnosis of infertility or claims for infertility treatments from medical records. The outcomes included: gestational glucose tolerance (gestational diabetes, impaired glucose tolerance, isolated hyperglycemia vs. normoglycemia), hypertensive disorders (gestational hypertension/preeclampsia vs. normotension), gestational weight gain (inadequate/excessive vs. adequate), systolic (SBP) and diastolic blood pressure, birthweight-for-gestational age z-score (tertile 2 and 3 vs. 1), preterm birth (<37 vs. ≥37 weeks at delivery), and birth outcome (pregnancy loss vs. live birth). We performed linear and logistic/multinomial regression analyses adjusted for age, race/ethnicity, age at menarche, pre-pregnancy BMI, and prenatal smoking.

Results

Mean (SD) age was 32.0 (5.0) years, and 18.8% of women had history of infertility, 32.6% of whom used MAR. SBP across pregnancy was 0.72 mmHg higher in women with vs. without infertility (95% CI 0.02, 1.42). The associations were stronger among women who used MAR (β 1.32 mmHg, 95% CI 0.21, 2.44), especially among those who used gonadotropins or gonadotropin-releasing hormone [GnRH] agonists (β 1.91 mmHg, 95% CI 0.48, 3.35). Other outcomes were not associated with history of infertility.

Conclusions

A history of infertility was associated with higher SBP during pregnancy, with stronger associations among those who used gonadotropins or GnRH agonists. Future studies are needed to confirm these findings and determine their clinical implications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04885-8.

Suppression of Adenosine Deaminase and Xanthine Oxidase Activities by Mineralocorticoid and Glucocorticoid Receptor Blockades Restores Renal Antioxidative Barrier in Oral Contraceptive-Treated Dam

OBJECTIVE

We tested the hypothesis that postpartum combined oral contraceptive (COC) treatment would induce oxidative stress via the adenosine deaminase-xanthine oxidase pathway in the kidney. We also sought to determine whether mineralocorticoid receptor (MR) or glucocorticoid receptor (GR ) blockade would suppress the activities of ADA and xanthine oxidase caused by postpartum COC treatment in the kidney.

METHODS

Twenty-four Wistar dams were randomly assigned to 4 groups (n = 6/group). Dams received vehicle (po), COC (1.0 μg ethinylestradiol and 5.0 μg levonorgestrel; po), COC with GR blockade (mifepristone; 80.0 mg/kg; po), and COC with MR blockade (spironolactone; 0.25 mg/kg; po) daily between 3rd and 11th week postpartum.

RESULTS

Data showed that postpartum COC caused increased plasma creatinine and urea, increased renal triglyceride/high-density lipoprotein ratio, free fatty acid accumulation, alanine aminotransferase, gamma-glutamyltransferase, uric acid, and activities of renal XO and ADA. On the other hand, postpartum COC resulted in decreased plasma albumin, renal glutathione, and Na+-K+-ATPase activity with no effect on lactate production. However, MR or GR blockade ameliorated the alterations induced by postpartum COC treatment. The present results demonstrate that MR or GR blockade ameliorates postpartum COC-induced increased activities of ADA and xanthine oxidase and restores glutathione-dependent antioxidative defense.

CONCLUSION

These findings implicate the involvements of GR and MR in renal dysfunctions caused by COC in dams via disrupted glutathione antioxidative barrier.

Determinants of Maternal Renin-Angiotensin-Aldosterone-System Activation in Early Pregnancy: Insights From 2 Cohorts

CONTEXT

The corpus luteum (CL) secretes prorenin, renin's inactive precursor. It may thus contribute to the renin-angiotensin-aldosterone-system (RAAS) activation that is required for maternal adaptation in pregnancy. Whether this activation is disturbed in pregnancies lacking a CL is unknown.

OBJECTIVE

The objective of this work is to investigate maternal RAAS determinants in early pregnancy.

DESIGN AND SETTING

Two observational prospective cohort studies.

TOOK PLACE AT

2 tertiary referral hospitals.

PATIENTS AND INTERVENTION(S)

Pregnancies (n = 277) were stratified by CL number and in vitro fertilization (IVF) protocol: 0 CL (programmed cycle frozen embryo transfer [FET], n = 28), 1 CL (natural cycle FET, n = 41 and spontaneous conceptions, n = 139), and more than 1 CL (ovarian stimulation and fresh embryo transfer, n = 69).

METHODS

Quantification was performed for maternal prorenin, renin, and aldosterone blood levels at 5, 9, and 11 weeks of gestation.

RESULTS

Prorenin and renin were lower in the absence of a CL at all time points when compared to 1 CL, whereas prorenin, renin, and aldosterone were higher in the presence of more than 1 CL vs 1 CL (P < .05). Ovarian stimulation with menopausal gonadotropin resulted in higher prorenin, renin, and aldosterone concentrations during the late first trimester than recombinant follicle-stimulating hormone (P < .05). Prorenin, and to a lesser degree renin, correlated positively with serum progesterone and relaxin, but not serum estradiol. Total follicle diameter, body mass index (BMI), polycystic ovary syndrome (PCOS), and antimüllerian hormone (AMH) were additional determinants of circulating prorenin. Finally, pregnancies conceived in the absence of a CL were more disposed to develop preeclampsia.

CONCLUSIONS

CL number, IVF protocol, BMI, PCOS, and AMH affect maternal RAAS activation in early pregnancy, and may thus contribute to pregnancy complications.

Pannexin 1 channels in renin-expressing cells influence renin secretion and blood pressure homeostasis

Kidney function and blood pressure homeostasis are regulated by purinergic signaling mechanisms. These autocrine/paracrine signaling pathways are initiated by the release of cellular ATP, which influences kidney hemodynamics and steady-state renin secretion from juxtaglomerular cells. However, the mechanism responsible for ATP release that supports tonic inputs to juxtaglomerular cells and regulates renin secretion remains unclear. Pannexin 1 (Panx1) channels localize to both afferent arterioles and juxtaglomerular cells and provide a transmembrane conduit for ATP release and ion permeability in the kidney and the vasculature. We hypothesized that Panx1 channels in renin-expressing cells regulate renin secretion in vivo. Using a renin cell-specific Panx1 knockout model, we found that male Panx1 deficient mice exhibiting a heightened activation of the renin-angiotensin-aldosterone system have markedly increased plasma renin and aldosterone concentrations, and elevated mean arterial pressure with altered peripheral hemodynamics. Following ovariectomy, female mice mirrored the male phenotype. Furthermore, constitutive Panx1 channel activity was observed in As4.1 renin-secreting cells, whereby Panx1 knockdown reduced extracellular ATP accumulation, lowered basal intracellular calcium concentrations and recapitulated a hyper-secretory renin phenotype. Moreover, in response to stress stimuli that lower blood pressure, Panx1-deficient mice exhibited aberrant "renin recruitment" as evidenced by reactivation of renin expression in pre-glomerular arteriolar smooth muscle cells. Thus, renin-cell Panx1 channels suppress renin secretion and influence adaptive renin responses when blood pressure homeostasis is threatened.

Ovarian status modulates cardiovascular autonomic control and oxidative stress in target organs

Studies have presented conflicting findings regarding the association between both fluctuation and deprivation of ovarian hormones and cardiovascular autonomic modulation and oxidative stress and their potential impact on resting arterial pressure (AP) and cardiovascular risk. This study aimed to assess cardiovascular autonomic modulation, baroreflex sensitivity (BRS), and oxidative stress in male rats (M) and in female rats during ovulatory (FOV) and non-ovulatory phases (FNOV) of the estrous cycle and after deprivation of ovarian hormones (FO). Direct AP was recorded, and BRS was assessed by using increasing doses of phenylephrine and sodium nitroprusside. AP and heart rate variability were assessed by spectral analysis. Oxidative stress profile was evaluated in cardiac, renal, and muscle tissues. In females, the ovulatory phase and ovarian hormone deprivation induced an increase in AP (FOV and FO ~ 9 mmHg) when compared to the non-ovulatory phase. Ovariectomy promoted increased cardiac sympathovagal balance (~ 17–37%) when compared to other groups. Both FOV and FO groups presented impaired BRS, associated with higher AP variability. In general, antioxidant capacity was higher in the FNOV than in the M group. Ovarian hormone deprivation induced a decrease in catalase activity in cardiac and renal tissues and an increase in lipid peroxidation in all tissues analyzed. Positive correlations (p < 0.05) were found between vascular sympathetic modulation and lipid peroxidation in cardiac (r = 0.60), renal (r = 0.60), and muscle (r = 0.57) tissues. In conclusion, both oscillation and deprivation of ovarian hormones play an important role in cardiovascular autonomic control and oxidative stress profile in target organs, which is reflected in AP changes.

Plasma volume variation across the menstrual cycle among healthy women of reproductive age: A prospective cohort study

Increases in reproductive hormones like estrogen, play an important role in the remarkable increases in plasma volume observed in pregnancy. Accurate estimates of plasma volume expansion during pregnancy depend on correctly timing and measuring plasma volume in nonpregnant women. However, to date, there is no consensus on the pattern of plasma volume across the menstrual cycle. We prospectively measured plasma volume in 45 women across a single menstrual cycle. A urine-based fertility monitor was used to time three clinic visits to distinct points in the menstrual cycle: the early follicular phase (~day 2), periovulation (~day 12), and the mid-point of the luteal phase (~day 21)-based on a 28-day cycle length. Healthy women aged 18-41 years with regular menstrual cycles and a healthy body weight were enrolled in the study. At each visit, blood samples were collected before and after injection of 0.25 mg/kg body weight of indocyanine green dye (ICG). Pre- and post-ICG injection plasma samples were used to measure plasma volume. Preinjection samples were used to measure ovarian hormones and plasma osmolality. Mean plasma volume was highest during the early follicular phase (2,276 ± 478 ml); it declined to 2,232 ± 509 ml by the late follicular phase and to 2,228 ± 502 ml by the midluteal phase. This study found that overall variations in plasma volume are small across the menstrual cycle. Therefore, in clinical practice and research, the menstrual cycle phase may not be an important consideration when evaluating plasma volume among women of reproductive age.

Changes in biochemical tests in pregnancy and their clinical significance

Interpretation of laboratory investigations relies on reference intervals. Physiological changes in pregnancy may result in significant changes in normal values for many biochemical assays, and as such results may be misinterpreted as abnormal or mask a pathological state. The aims of this review are as follows: 1. To review the major physiological changes in biochemical tests in normal pregnancy. 2. To outline where these physiological changes are important in interpreting laboratory investigations in pregnancy. 3. To document the most common causes of abnormalities in biochemical tests in pregnancy, as well as important pregnancy-specific causes.

Arterial stiffness during controlled ovarian hyperstimulation and early pregnancy in women exposed to assisted reproduction

INTRODUCTION

Female sex hormones have vasorelaxing effects in non-pregnant and pregnant women. We aimed to investigate the effect of controlled ovarian hyperstimulation (COH) for in vitro fertilization (IVF), and early pregnancy, on arterial stiffness as assessed by digital pulse wave analysis (DPA), hypothesizing reduced arterial stiffness as an effect of increased estrogen levels.

MATERIAL AND METHODS

A total of 68 women undergoing IVF were examined with DPA before conception and during IVF treatment with COH and embryo transfer (ET), and in gestational week seven in 19 women who became pregnant. Heart rate (HR), mean arterial pressure (MAP) and the DPA variables cardiac ejection elasticity index (EEI), b/a, dicrotic index (DI), d/a and aging index (AI) were measured.

RESULTS

HR was significantly increased at all measuring points (p ≤ 0.003) but MAP only at ET (p 0.007). DPA variables representing large arteries (EEI, b/a) and peripheral arteries (DI, but not d/a), and the global variable AI, indicated increased arterial stiffness at ET compared with baseline (p ≤ 0.035). No DPA variable was significantly changed at pregnancy measurements compared to baseline.

CONCLUSION

During COH for IVF treatment, DPA showed no changes in arterial stiffness during the follicular phase or in early pregnancy, but increased arterial stiffness in central and peripheral arteries in the early luteal phase. The result suggests a hormonal hemodynamic activation counteracting the effects of estrogen.

Hypertensive Disorders in Pregnant Women Receiving Fertility Treatments

Hypertensive disorders (HDs) as the most prevalent medical problem during pregnancy, predispose the patient to a lot of comorbidities and may even cause maternal or fetal death. The rate of infertility has been increasing in recent decades. So, we collected and summarized data about the co-existence of these two entities and found that HDs are somewhat more common in women receiving fertility treatments regardless of pathophysiologic correlation of infer- tility and hypertension or older age and chance of multiple pregnancies.

Salt, aldosterone and extrarenal Na+ - sensitive responses in pregnancy

Outside of pregnancy excessive salt consumption is known to be harmful being linked to increased blood pressure and cardiovascular disease. However, pregnancy represents a major change to a woman's physiology resulting in an intimate adaptation to environmental conditions. It is now becoming apparent that salt is essential for a number of these changes during pregnancy including haematological, cardiac adaptations as well as directly influencing placental development and the uteroplacental immune environment. The present review discusses the important role that salt has during normal pregnancy and evidence will also be presented to show how the placenta may act as a salt sensing organ temporarily, yet substantially regulating maternal blood pressure.

•

The placenta may function as an extrarenal regulator of maternal blood pressure.

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Na⁺handling in pregnancy is completely different to the non-pregnant situation.

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Na⁺may actually lower blood pressure in pregnancy affected with pre-eclampsia.

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Aldosterone is an important regulator of placental and fetal development.

•

Na⁺ may compensate for aldosterone deficiency in pregnancy.

Management of a severe case of Gitelman syndrome with poor response to standard treatment

Gitelman syndrome is an autosomal recessive distal renal tubular disorder caused by defective sodium chloride transporters. Biochemically, it presents with hypokalaemic metabolic alkalosis, hypomagnesaemia and hypocalciuria. It is usually managed with oral potassium supplements and potassium-sparing diuretics. We report a case of a 28-year-old woman whose condition worsened during pregnancy; she became resistant to standard management after delivery of her second child. She was managed in a specialist metabolic clinic through a comprehensive approach including perseverance with oral potassium supplement, weekly intravenous potassium and magnesium infusion, correction of vitamin D level and the offering of appropriate dietary advice; this controlled the patient's symptoms and prevented repeated hospital admissions. In this case report, we illustrate a patient's presentation and diagnosis with Gitelman syndrome, discuss triggers of exacerbation, review the relevant literature in terms of differential diagnoses and provide practical advice on the management of difficult cases in a specialist clinic.

Role of ACTH and Other Hormones in the Regulation of Aldosterone Production in Primary Aldosteronism

The major physiological regulators of aldosterone production from the adrenal zona glomerulosa are potassium and angiotensin II; other acute regulators include adrenocorticotropic hormone (ACTH) and serotonin. Their interactions with G-protein coupled hormone receptors activate cAMP/PKA pathway thereby regulating intracellular calcium flux and CYP11B2 transcription, which is the specific steroidogenic enzyme of aldosterone synthesis. In primary aldosteronism (PA), the increased production of aldosterone and resultant relative hypervolemia inhibits the renin and angiotensin system; aldosterone secretion is mostly independent from the suppressed renin-angiotensin system, but is not autonomous, as it is regulated by a diversity of other ligands of various eutopic or ectopic receptors, in addition to activation of calcium flux resulting from mutations of various ion channels. Among the abnormalities in various hormone receptors, an overexpression of the melanocortin type 2 receptor (MC2R) could be responsible for aldosterone hypersecretion in aldosteronomas. An exaggerated increase in plasma aldosterone concentration (PAC) is found in patients with PA secondary either to unilateral aldosteronomas or bilateral adrenal hyperplasia (BAH) following acute ACTH administration compared to normal individuals. A diurnal increase in PAC in early morning and its suppression by dexamethasone confirms the increased role of endogenous ACTH as an important aldosterone secretagogue in PA. Screening using a combination of dexamethasone and fludrocortisone test reveals a higher prevalence of PA in hypertensive populations compared to the aldosterone to renin ratio. The variable level of MC2R overexpression in each aldosteronomas or in the adjacent zona glomerulosa hyperplasia may explain the inconsistent results of adrenal vein sampling between basal levels and post ACTH administration in the determination of source of aldosterone excess. In the rare cases of glucocorticoid remediable aldosteronism, a chimeric CYP11B2 becomes regulated by ACTH activating its chimeric CYP11B1 promoter of aldosterone synthase in bilateral adrenal fasciculate-like hyperplasia. This review will focus on the role of ACTH on excess aldosterone secretion in PA with particular focus on the aberrant expression of MC2R in comparison with other aberrant ligands and their GPCRs in this frequent pathology.

Infertility, fertility treatment, and risk of hypertension

OBJECTIVE

To evaluate the association between infertility and fertility treatments on subsequent risk of hypertension.

DESIGN

Cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 116,430 female nurses, followed from 1993 to June 2011, as part of the Nurses' Health Study II cohort.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Self-reported, physician-diagnosed hypertension.

RESULT(S)

Compared with women who have never reported infertility, infertile women were at no greater risk of hypertension (multivariable adjusted relative risk (RR) = 1.01, with 95% confidence interval [CI] [0.94-1.07]). Infertility due to tubal disease was associated with a higher risk of hypertension (RR = 1.15 [1.01-1.31]), but no other diagnoses were associated with hypertension risk, compared with women who did not report infertility (ovulatory disorder: RR = 1.03 [0.94-1.13]; cervical: RR = 0.88 [0.70-1.10]; male factor: RR = 1.05 [0.95-1.15]; other reason: RR = 1.02 [0.94-1.11]; reason not found: RR = 1.02 [0.95-1.10]). Infertile women collectively had 5,070 cases of hypertension. No clear pattern between use of fertility treatment and hypertension was found among infertile women (clomiphene citrate: RR = 0.97 [0.90-1.04]; gonadotropin alone: RR = 0.97 [0.87-1.08]; intrauterine insemination: RR = 0.86 [0.71-1.03]; in vitro fertilization: RR = 0.86 [0.73-1.01]).

CONCLUSION(S)

Among this relatively young cohort of women, no apparent increase occurred in hypertension risk among infertile women, or among women who had undergone fertility treatment previously.

Hormones and hemodynamics in pregnancy

CONTEXT

Normal pregnancy is associated with sodium and water retention, which results in plasma volume expansion prior to placental implantation. The explanation offered for these events is that pregnancy 'resets' both volume and osmoreceptors.

EVIDENCE ACQUISITION

The mechanisms for such an enigmatic 'resetting' in pregnancy have not previously been explained. However, recent human pregnancy studies have demonstrated that the earliest hemodynamic change in pregnancy is primary systemic arterial vasodilation. This arterial underfilling is associated with a secondary increase in cardiac output and activation of the neurohumoral axis, including stimulation of the renin-angiotensin-aldosterone, sympathetic, and non-osmotic vasopressin systems. Resistance to the pressor effects of angiotensin and sympathetic stimulation in pregnancy is compatible with an increase in endothelial nitric oxide synthase activity.

RESULTS

In contrast to the sodium and water retention which occur secondary to the primary arterial vasodilation in cirrhosis, glomerular filtration and renal blood flow are significantly increased in normal pregnancy. A possible explanation for this difference in arterial vasodilation states is that relaxin, an arterial vasodilator which increases during pregnancy, has a potent effect on both systemic and renal circulation. Endothelial damage in pregnancy is pivotal in the pathogenesis of preeclampsia in pregnancy.

CONCLUSIONS

Against a background of the primary arterial vasodilation hypothesis, it is obvious that reversal of the systemic vasodilatation in pregnancy, without subsequent activation of the renin-angiotensin-aldosterone system (78), will evoke a reversal of all the links in the chain of events in normal pregnancy adaptation, thus, it may cause preeclampsia. Namely, a decrease of renal vasodilation will decrease glomerular filtration rate.

Matrix metalloproteinases as drug targets in preeclampsia

Preeclampsia is an important syndrome complicating pregnancy. While the pathogenesis of preeclampsia is not entirely known, poor placental perfusion leading to widespread maternal endothelial dysfunction is accepted as a major mechanism. It has been suggested that altered placental expression of matrix metalloproteinases (MMPs) may cause shallow cytotrophoblastic invasion and incomplete remodeling of the spiral arteries. MMPs are also thought to link placental ischemia to the cardiovascular alterations of preeclampsia. In fact, MMPs may promote vasoconstriction and surface receptors cleavage affecting the vasculature. Therefore, the overall goal of this review article is to provide an overview of the pathophisiology of preeclampsia, more specifically regarding the role of MMPs in the pathogenesis of preeclampsia and the potential of MMP inhibitors as therapeutic options.

Ovarian cycle and sympathoexcitation in premenopausal women

The influence of the ovarian cycle on muscle sympathetic nerve activity (MSNA) remains controversial. Some studies report an increase of resting MSNA during the mid luteal (ML) phase of the ovarian cycle compared with the early follicular phase, whereas other studies do not. These inconsistent findings may be attributable, in part, to the variable surges in estradiol and progesterone. We tested the hypothesis that the degree of sympathoexcitation during the ML phase (ΔMSNA) is associated with changes in estradiol (ΔE(2)) and progesterone (ΔP). Multiple regression analysis of data from previous studies with complete recordings of mean arterial pressure, MSNA, E(2), and P during both early follicular and ML phases were available from 30 eumenorrheic women (age, 28 ± 1 years; body mass index, 23 ± 0 kg/m(2)). ML phase increased E(2) (37 ± 2 to 117 ± 9 pg/mL; P<0.001), P (1 ± 0 to 11 ± 1 ng/mL; P<0.001), and MSNA (12 ± 1 to 15 ± 1 bursts/min; P=0.02), but did not alter mean arterial pressure (83 ± 2 to 83 ± 2 mm Hg; P=0.91). ΔMSNA was correlated with ΔE(2) (r=-0.50, P=0.003) and ΔE(2)/ΔP (r=-0.52, P=0.002) but not ΔP (r=0.21, P=0.13). There was no association between Δmean arterial pressure and ΔE(2) (r=-0.13, P=0.49), ΔP (r=-0.04, P=0.83), or ΔE(2)/ΔP (r<0.01, P=0.98). In conclusion, sympathoexcitation during the ML phase of the ovarian cycle seems to be dependent, in part, on the degree of sex steroid surges. This dynamic interaction among E(2), P, and MSNA likely explains previously reported inconsistencies in the field; it remains possible that other sex steroids, such as testosterone, might explain further variance.

Menstrual cycle affects renal-adrenal and hemodynamic responses during prolonged standing in the postural orthostatic tachycardia syndrome

Approximately 500,000 American premenopausal women have the postural orthostatic tachycardia syndrome (POTS). We tested the hypothesis that in POTS women during orthostasis, activation of the renin-angiotensin-aldosterone system is greater, leading to better compensated hemodynamics in the midluteal phase (MLP) than in the early follicular phase of the menstrual cycle. Ten POTS women and 11 healthy women (controls) consumed a constant diet 3 days before testing. Hemodynamics and renal-adrenal hormones were measured while supine and during 2-hour standing. We found that blood pressure was similar, heart rate and total peripheral resistance were greater, and cardiac output and stroke volume were lower in POTS subjects than in controls during 2-hour standing. In controls, hemodynamic parameters were indistinguishable between menstrual phases. In POTS subjects, cardiac output and stroke volume were lower and total peripheral resistance was greater in the early follicular phase than MLP after 30 minutes of standing; however, blood pressure and heart rate were similar between phases. Plasma renin activity (9+/-6 [SD] versus 13+/-9 ng/mL per hour; P=0.04) and aldosterone (43+/-22 versus 55+/-25 ng/dL; P=0.02) were lower in the early follicular phase than MLP in POTS subjects after 2 hours of standing. Catecholamine responses were similar between phases. The percentage rate of subjects having presyncope was greater in the early follicular phase than MLP for both groups (chi(2) P<0.01). These results suggest that the menstrual cycle modulates the renin-angiotensin-aldosterone system and affects hemodynamics during orthostasis in POTS. The high estrogen and progesterone in the MLP are associated with greater increases in renal-adrenal hormones and presumably more volume retention, which improve late-standing tolerance in these patients.

Autonomic circulatory control during pregnancy in humans

Pregnancy is associated with dramatic alterations in maternal hemodynamics, which begin as early as 4 to 5 weeks of gestation. It has been proposed that these changes occur through autonomic control mechanisms, but the actual role of the autonomic nervous system in pregnancy is poorly understood. Here, we review what is known about the hemodynamic adaptation, changes in vascular endothelial function, sympathetic neural control and vascular responsiveness in pregnancy, and baroreflex function during pregnancy in humans. However, whether and how the sympathetic nervous system plays a role in hemodynamic homeostasis during EARLY human pregnancy remains completely unknown. Understanding the pathophysiology underlying autonomic control of maternal hemodynamics may be particularly important for prevention of cardiovascular complications during pregnancy and may improve risk stratification and prevention of cardiovascular disease for women well beyond the postpartum period.

Factors correlated with plasma renin activity in general Japanese population

BACKGROUND

The renin-angiotensin-aldosterone system plays a pivotal role in regulation of blood pressure and electrolyte homeostasis and is a target in the treatment of hypertension and renal diseases. However, the factors correlated with plasma renin activity (PRA) are unclarified in general Japanese population. To examine this point, we conducted a community-based cross-sectional study.

METHODS

Subjects of this study were 2,056 individuals (mean age, 61 years; 934 men; 1,122 women) over 40-year-old without antihypertensive medication in Takahata town, Japan. PRA was measured by radioimmunoassay. Estimated 24-h urine sodium (e24hUNa) and potassium excretion were calculated from morning spot urine.

RESULTS

The median value of PRA was higher in men compared to women (1.1 ng/ml/h vs. 0.7 ng/ml/h, P < 0.001). The increased PRA (>2.0 ng/ml/h) were detected in 248 men (26.3%) and 142 women (12.7%). One-factor analysis of variance showed that PRA was correlated with blood pressure, uric acid, hemoglobin, total protein, total cholesterol, low-density lipoprotein cholesterol, serum adiponectin and e24hUNa in men. In women, PRA was correlated with age, blood pressure, total protein, high-density lipoprotein cholesterol (HDL-C), serum insulin, e24hUNa and obesity. Multivariate logistic regression analysis showed that high PRA (>2.0 ng/ml/h) was independently associated with low blood pressures, low e24UNa and high serum total protein both in men and women, smoking only in men and high HDL-C only in women, respectively.

CONCLUSIONS

This study revealed that PRA was higher in men than women and was associated negatively with blood pressures and urine sodium excretion, and positively with total protein, smoking and HDL-C in Japanese population.

Corneal topographic changes in premenopausal and postmenopausal women

BACKGROUND

To asses the effect of menopause on the corneal curvature changes using corneal computerized videokeratography (CVK) in premenopausal and postmenopausal healthy women.

METHODS

Thirty-six postmenopausal women with mean ages of 49.2 (range 39 to 57) were enrolled in this randomized, prospective study, comparing with 26 healthy controls with mean ages of 38.5 +/- 4.9 (range 32 to 49). Subjects were determined to be postmenopausal, by the Gynecology and Obstetrics Department, based on blood Follicular Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estradiol, Progesterone levels and clinical complaints. Complete ophthalmic examination and CVK using Haag-Streit System was performed in both premenopausal and postmenopausal women.

RESULTS

Mean horizontal curvature and vertical curvature of central corneal power in premenopausal women were 43.5 +/- 1.25 Diopter (D), and 44.1 +/- 1.53 D. Mean horizontal curvature and vertical curvature of central corneal power in postmenopausal women were 43.9 +/- 1.4 D, and 44.6 +/- 1.3 D. The mean keratometric astigmatisms of premenopausal and postmenopausal women were 0.81 +/- 0.57 D (4-179 degrees), 0.74 degrees +/- 0.5 D (1-180 degrees) respectively. No significant corneal curvature changes were detected between premenopausal and postmenopausal groups (P > 0.05). On the other hand, we only found negative but significant correlation between horizontal corneal curvature and estrogen level of postmenopausal women (r = -0.346, p = 0.038).

CONCLUSION

Menopause is physiologic process and may also affect corneal topographic changes. In postmenopausal women, corneal steeping was observed minimally compared to premenopausal women. The results suggest that changes in estrogen level of women with menopause are associated with slightly alteration of horizontal curvature of cornea.

Effects of gender on the renin-angiotensin system, blood pressure, and renal function

Recent studies have identified key gender differences in cardiovascular function, renal hemodynamics, and the renin-angiotensin system. Extensive epidemiologic evidence has shown a clear gender difference in cardiovascular and renal disease progression, whereby female sex appears to be protective. The mechanisms underlying this phenomenon are unknown, but likely reflect the aforementioned sex differences in common pathophysiologic pathways. This review focuses on studies examining sex differences in these underlying pathways, which together may provide a plausible mechanism for the gender disparity in clinical outcomes.