Gender difference in age-related changes in vascular function

Metabolic and microvascular function assessed using near-infrared spectroscopy with vascular occlusion in women: age differences and reliability

NEW FINDINGS

What is the central question of this study? Can the near-infrared spectroscopy with vascular occlusion test (NIRS-VOT) reliably measure skeletal muscle metabolic and microvascular function in women? What is the main finding and its importance? The NIRS-VOT can be used as a reliable technique for the assessment of skeletal muscle metabolism and microvascular function in women, with reliability being generally greater in younger women. These findings have important implications for the planning and development of future studies employing the NIRS-VOT in women, and provide insights into the effects of age on these parameters in women specifically.

ABSTRACT

We investigated the test-retest reliability of, and age-related differences in, markers of skeletal muscle metabolism and microvascular function derived from the near-infrared spectroscopy with vascular occlusion test (NIRS-VOT) in younger women (YW) and middle-aged and older women (MAOW). Seventeen YW (age 23 ± 4 years) and 17 MAOW (age 59 ± 8 years) completed this study. Participants completed identical experimental visits separated by ∼4 weeks during which the NIRS-VOT was used to quantify the occlusion slope, minimum and maximum tissue saturation, ischaemic index, reperfusion magnitude, the reperfusion and 10-s reperfusion slopes (slope 2 and slope 210-s ), time to max tissue saturation, and area under the reperfusion curve using the local tissue oxygen saturation signal. Except for slope 210-s (intraclass correlation coefficient (ICC) = 0.37; coefficient of variation (CV) = 31%), time to max tissue saturation (ICC = 0.21), and ischaemic index (ICC = 0.37) for MAOW, all of the NIRS variables demonstrated good to excellent relative reliability for the YW (ICCs = 0.74-0.86) and the MAOW (ICCs = 0.51-0.87), with CVs of 2-21% and 2-22%, respectively. The occlusion slope was significantly lower, indicating accelerated deoxygenation, while maximum tissue saturation, reperfusion magnitude, and ischaemic index were significantly higher in YW versus MAOW. No other group differences were found. In conclusion, our data support the use of the NIRS-VOT as a simple, reliable, non-invasive technique for the assessment of peripheral skeletal muscle metabolism and microvascular function in women, with the reliability being generally greater in YW versus MAOW. Further, our data suggest that ageing is associated with lower skeletal muscle metabolism and microvascular hyperaemic responsiveness in women.

Impact of prolonged sitting interruption strategies on shear rate, flow-mediated dilation and blood flow in adults: A systematic review and meta-analysis of randomized cross-over trials

Prolonged sitting has been shown to affect endothelial function. Strategies that promote interruption of sitting have shown varying results on the shear rate (SR), flow-mediated dilation (FMD) and blood flow (BF). Thus, we conducted a systematic review and meta-analysis to 1) increase the existing knowledge of the impact of sitting interruption in the prevention of endothelial dysfunction in adults and 2) determine the effect of the sitting interruption strategies on SR, FMD, BF. Literature search was carried out through 7 databases. A random effects model was used to provide the overall mean difference with a 95%CI, and forest plots were generated for pooled estimates of each study outcome. Assessment of biases was performed using ROB2 and considerations for crossover trials. Prolonged sitting interruption strategies showed a significant effect in increasing SR (MD: 7.58 s^-1; 95% CI: 3.00 to 12.17), FMD (MD: 1.74%; 95% CI: 0.55 to 2.93) and BF (MD: 12.08 ml/min; 95% CI: 7.61 to 16.55) when compared with the uninterrupted prolonged sitting condition. Prolonged sitting interruption strategies significantly increase SR, FMD and BF, therefore, they represent a considerable effective preventive method on endothelial dysfunction caused by acute exposure to uninterrupted prolonged sitting.

High Frequency of Microvascular Dysfunction in US Outpatient Clinics: A Sign of High Residual Risk? Data from 7,105 Patients

Previous studies have linked peripheral microvascular dysfunction measured by arterial tonometry to high residual risk in on-statin patients. Digital thermal monitoring (DTM) of microvascular function is a new and simplified technique based on fingertip temperature measurements that has been correlated with the burden of atherosclerosis and its risk factors. Here, we report analyses of DTM data from two large US registries: Registry-I (6,084 cases) and Registry-II (1,021 cases) across 49 US outpatient clinics. DTM tests were performed using a VENDYS device during a 5-minute arm-cuff reactive hyperemia. Fingertip temperature falls during cuff inflation and rebounds after deflation. Adjusted maximum temperature rebound was reported as vascular reactivity index (VRI). VRI distributions were similar in both registries, with mean ± SD of 1.58 ± 0.53 in Registry-I and 1.52 ± 0.43 in Registry-II. In the combined dataset, only 18% had optimal VRI (≥2.0) and 82% were either poor (<1.0) or intermediate (1.0-2.0). Women had slightly higher VRI than men (1.62 ± 0.56 vs. 1.54 ± 0.47, p < 0.001). VRI was inversely but mildly correlated with age (r = −0.19, p < 0.001). Suboptimal VRI was found in 72% of patients <50 years, 82% of 50-70 years, and 86% of ≥70 years. Blood pressure was not correlated with VRI. In this largest registry of peripheral microvascular function measurements, suboptimal scores were highly frequent among on-treatment patients, possibly suggesting a significant residual risk. Prospective studies are warranted to validate microvascular dysfunction as an indicator of residual risk.

An in silico simulation of flow-mediated dilation reveals that blood pressure and other factors may influence the response independent of endothelial function

Endothelial dysfunction is thought to underpin atherosclerotic cardiovascular disease. The most widely used in vivo test of endothelial function is flow-mediated dilation (FMD). However, the results of FMD may be subject to some confounding factors that are not fully understood. We investigated potential biophysical confounding factors that could cause a disassociation between FMD and true endothelial cell shear stress response (the release of endothelium-dependent relaxing factors in response to wall shear stress). Arterial hemodynamics during FMD was simulated using a novel computational modeling approach. The model included an endothelial response function relating changes in wall shear stress to changes in local vascular stiffness in the arm arteries and accounted for vascular stiffening with increasing blood pressure. The hemodynamic effects of cuff inflation and deflation were modeled by prescribing intraluminal arterial pressure changes and peripheral vasodilation. Evolution of arterial diameter and flow velocity during FMD was assessed by comparison against in vivo data. Our model revealed that vasoconstriction occurring immediately after cuff deflation is independent of endothelial response function and entirely caused by the change in transmural pressure along conduit arteries. Moreover, for the same endothelial response function model, FMD values increased exponentially with increasing peak flow velocity, decreased linearly with increasing arterial stiffness at a rate of 0.95%/MPa, and increased linearly with increasing central blood pressure at a rate of 0.22%/mmHg. Dependence of FMD on confounding factors, such as arterial stiffness and blood pressure, suggests that the current FMD test may not reflect the true endothelial cell response.NEW & NOTEWORTHY First, a novel computational model simulating arterial hemodynamics during flow-mediated dilation (FMD) was proposed. Second, the model was used to explain why FMD may be influenced by endothelium-independent factors, showing that FMD results are 1) partly masked by the vasoconstriction due to the change in transmural pressure and 2) affected by physiological factors (i.e., arterial stiffness and arterial blood pressure) that are difficult to eliminate due to their multiple interactions.

Effect of chronic nitrate and citrulline supplementation on vascular function and exercise performance in older individuals

Increased nitric oxide (NO) bioavailability may improve exercise performance and vascular function. It remains unclear whether older adults who experience a decreased NO bioavailability may benefit from chronic NO precursor supplementation. This randomised, double-blind, trial aims to assess the effect of chronic NO precursor intake on vascular function and exercise performance in older adults (60-70 years old). Twenty-four healthy older adults (12 females) performed vascular function assessment and both local (knee extensions) and whole-body (incremental cycling) exercise tests to exhaustion before and after one month of daily intake of a placebo (PLA) or a nitrate-rich salad and citrulline (N+C, 520mg nitrate and 6g citrulline) drink. Arterial blood pressure (BP) and stiffness, post-ischemic, hypercapnic and hypoxic vascular responses were evaluated. Prefrontal cortex and quadriceps oxygenation was monitored by near-infrared spectroscopy. N+C supplementation reduced mean BP (-3.3mmHg; p=0.047) without altering other parameters of vascular function and oxygenation kinetics. N+C supplementation reduced heart rate and oxygen consumption during submaximal cycling and increased maximal power output by 5.2% (p<0.05), but had no effect on knee extension exercise performance. These results suggest that chronic NO precursor supplementation in healthy older individuals can reduce resting BP and increase cycling performance by improving cardiorespiratory responses.

Decline of popliteal artery flow-mediated dilation with aging and possible involvement of asymmetric dimethylarginine in healthy men

Purpose

We examined the influences of age and gender on flow-mediated endothelial function and the involvement of the competitive inhibition of l-arginine in endothelial function.

Methods

We measured brachial and popliteal flow-mediated vasodilation (FMD) responses, nitrate/nitrite (NOx) concentrations, and plasma levels of asymmetric dimethylarginine (ADMA) in four healthy, nonsmoking groups: young men (mean 26 ± 2 years, n = 17), middle-aged men (mean 50 ± 3 years, n = 19), young women (mean 27 ± 2 years, n = 16), and middle-aged women (mean 51 ± 2 years, n = 18).

Results

In young men, we found no significant differences between brachial and popliteal artery FMDs (10.6 ± 1.5 vs 8.7 ± 1.6%, p = 0.06). However, the popliteal artery FMD was significantly lower than the brachial artery FMD in middle-aged men (11.4 ± 1.5 vs 6.4 ± 1.0%, p < 0.001). In women, we found no significant differences between brachial and popliteal artery FMDs in young and middle-aged individuals (young, p = 0.17; middle-aged, p = 0.08). Popliteal artery FMD correlated with plasma NOx and ADMA levels as well as with the NOx/ADMA ratio in men but not in women (r = 0.485, − 0.544, and 0.672, respectively).

Conclusion

We concluded that a decrease in flow-mediated endothelial function in arteries of the lower extremities was evident in healthy middle-aged men, but not in middle-aged women. The competitive inhibition of l-arginine may contribute to this decrease in men.

Long-Term Aerobic Exercise Improves Vascular Function Into Old Age: A Systematic Review, Meta-Analysis and Meta Regression of Observational and Interventional Studies

There is an emerging body of literature relating to the effectiveness of frequent aerobic exercise as a prophylactic for age-associated dysfunction of large arteries, yet systematic evaluation and precise estimate of this effect is unknown. We conducted a systematic review and meta-analysis of controlled studies examining flow mediated dilatation (FMD) of athletic older persons and otherwise healthy sedentary counterparts to (i) compare FMD as a determinant of endothelial function between athletes and sedentary individuals and, (ii) summarize the effect of exercise training on FMD in studies of sedentary aging persons. Studies were identified from systematic search of major electronic databases from inception to January 2018. Study quality was assessed before conducting a random effects meta-analysis to calculate a pooled ES (mean difference) with 95% CI's. Thirteen studies [4 interventional (n = 125); 10 cross-sectional [including one study from the interventional analysis; (n = 485)] with age ranges from 62 to 75 years underwent quantitative pooling of data. The majority of study participants were male. Older athletes had more favorable FMD compared with sedentary controls (2.1%; CI: 1.4, 2.8%; P < 0.001). There was no significant improvement in the vascular function of sedentary cohorts following a period of exercise training (0.7%; CI: −0.675, 2.09%; P = 0.316). However, there was a significant increase in baseline diameter from pre to post intervention (0.1 mm; CI: 0.07, 0.13 mm; P < 0.001). In addition, there was no significant difference in endothelial independent vasodilation between the trained and sedentary older adults (1.57%; CI: −0.13, 3.27%; P = 0.07), or from pre to post exercise intervention (1.48%; CI: −1.34, 4.3%; P = 0.3). In conclusion, long-term aerobic exercise appears to attenuate the decline in endothelial vascular function, a benefit which is maintained during chronological aging. However, currently there is not enough evidence to suggest that exercise interventions improve vascular function in previously sedentary healthy older adults.

Sex differences in the vascular function and related mechanisms: role of 17β-estradiol

The incidence of cardiovascular disease (CVD) is lower in premenopausal women but increases with age and menopause compared with similarly aged men. Based on the prevalence of CVD in postmenopausal women, sex hormone-dependent mechanisms have been postulated to be the primary factors responsible for the protection from CVD in premenopausal women. Recent Women’s Health Initiative studies, Cochrane Review studies, the Early Versus Late Intervention Trial with Estradiol Study, and the Kronos Early Estrogen Prevention Study have suggested that beneficial effects of hormone replacement therapy (HRT) are seen in women of <60 yr of age and if initiated within <10 yr of menopause. In contrast, the beneficial effects of HRT are not seen in women of >60 yr of age and if commenced after 10 yr of menopause. The higher incidence of CVD and the failure of HRT in postmenopausal aged women could be partly associated with fundamental differences in the vascular structure and function between men and women and in between pre- and postmenopausal women, respectively. In this regard, previous studies from human and animal studies have identified several sex differences in vascular function and associated mechanisms. The female sex hormone 17β-estradiol regulates the majority of these mechanisms. In this review, we summarize the sex differences in vascular structure, myogenic properties, endothelium-dependent and -independent mechanisms, and the role of 17β-estradiol in the regulation of vascular function.

Mechanisms Responsible for Serotonin Vascular Reactivity Sex Differences in the Internal Mammary Artery

Background

The increased adverse cardiac events in women undergoing coronary artery bypass grafting are multifactorial and may include clinical, psychosocial, and biological factors. Potential contributing biological factors could include vascular hyperreactivity of the internal mammary artery (IMA) to endogenous vasoconstrictors in women, resulting in a predilection to myocardial ischemia. This study evaluated sex differences in serotonin and thromboxane A₂ dependent vasoconstriction in human isolated IMA, with the mechanistic role of (1) the endothelium, (2) nitric oxide (NO), (3) prostaglandins, and (4) receptor activity investigated for any observed sex difference.

Methods and Results

Viable isolated human IMA segments were obtained from 116 patients (44 women [mean age, 66.8±12.2 years] and 72 men [mean age, 66.6±10.4 years]) undergoing coronary artery bypass grafting. Cumulative concentration‐response curves for serotonin and thromboxane A₂ mimetic, U46619, were determined and revealed an increased sensitivity to serotonin but not U46619 in women. This sex difference to serotonin was further assessed by the following: (1) endothelial denudation, (2) endothelial NO synthase inhibition and NO quantification using electron paramagnetic resonance, (3) cyclooxygenase inhibition and prostaglandin metabolite quantification using mass spectrometry, and (4) quantification of receptor activity status. The female hyperreactivity to serotonin was (1) abolished by endothelial denudation; (2) unaffected by NO synthase inhibition, with no difference in electron paramagnetic resonance–assessed NO levels; (3) abolished by cyclooxygenase inhibition (quantification of prostaglandins in IMA revealed a trend towards reduced 6‐keto prostaglandin F1α in female IMA; P=0.08); and (4) unrelated to receptor activity.

Conclusions

These data indicate that female IMAs are hyperreactive to serotonin but not U46619, with the former attributable to an endothelium‐dependent cyclooxygenase pathway.

Endothelial dysfunction and menopause: is exercise an effective countermeasure?

Cardiovascular disease is the leading cause of death in women. There is a dramatic rise in risk factors for cardiovascular disease during the menopausal transition that is independent of aging. Endothelial dysfunction is an early hallmark of developing cardiovascular disease and has been shown to increase across the stages of menopause. Exercise is considered one of the most effective lifestyle therapies to maintain and improve endothelial function. However, accumulating evidence suggests that exercise does not have the same benefit on endothelial function in menopausal women as it does in other populations, and factors associated with menopause likely influence the endothelial responsiveness to exercise. This review will detail the current available evidence on endothelial dysfunction, exercise, and menopause, including mechanisms that may mediate the accumulating endothelial dysfunction in women with menopause, the impact of exercise on endothelial function in women, and whether regular exercise is an effective therapeutic and prevention strategy to maintain endothelial function with menopause. We conclude that the effect of exercise on endothelial function differs according to menopausal stage and cardiovascular disease risk burden. Finally, we will address critical gaps in the literature with the goal of identifying future research directions to improve healthy aging in women.

Associations between microalbuminuria and parameters of flow-mediated vasodilatation obtained by continuous measurement approaches

The associations between microalbuminuria and various parameters of flow-mediated vasodilatation (FMD) are not completely understood. We retrospectively analyzed 265 consecutive patients who underwent coronary angiography and in whom we could measure FMD and the urine albumin-creatinine ratio (UACR). Using 15 continuous measurement approaches, we measured FMD as the magnitude of the percentage change in the brachial artery diameter from baseline to peak (bFMD), the maximum FMD rate calculated as the maximal slope of dilation (FMD-MDR), and the integrated FMD response calculated as the area under the dilation curve during the 60- and 120-s dilation periods (FMD-AUC60 and FMD-AUC120). We divided the patients into two groups according to UACR: normoalbuminuria (NOR, n = 211) and microalbuminuria (MIC, n = 54). The MIC group showed a significantly higher percentage of coronary artery disease than the NOR group. FMD-AUC60 and FMD-AUC120, but not FMD-MDR, in the MIC group were significantly lower than those in the NOR group. On the other hand, bFMD in the MIC group tended to be lower than that in the NOR group, but this difference was not significant. A multiple regression analysis indicated that FMD-AUC120 and diabetes mellitus were predictors of MIC. Finally, we defined the cut-off value of FMD-AUC₁₂₀ for the presence of MIC in all patients as 8.4 mm x second (sensitivity 0.640, specificity 0.588) by a receiver-operating characteristic curve analysis. In conclusion, this study provides more definitive evidence for the association of microalbuminuria with endothelial dysfunction. FMD-AUC120 may be a superior marker for MIC.

Endothelial and kidney function in women with a history of preeclampsia and healthy parous controls: A case control study

INTRODUCTION

Preeclampsia (PE) is a pregnancy related endothelial disease characterized by hypertension and albuminuria. Postpartum endothelial dysfunction often persists in these women. We postulate that in women with a history of PE reduced endothelial dependent vasodilation coincides with attenuated kidney function, as both reflect endothelial dysfunction.

METHODS

We assessed endothelial and kidney function in women with a history of PE (n=79) and uncomplicated pregnancies (n=49) at least 4years postpartum. Women with hypertension, diabetes or kidney disease prior to pregnancy were excluded. Brachial artery flow mediated dilatation (FMD) was measured and analysed by a custom designed edge-detection and wall-tracking software. We measured albumin and creatinine levels in a 24-h urine sample and calculated glomerular filtration rate (GFR) by CKD-EPI.

RESULTS

Women with a history of PE had lower FMD but comparable GFR and albumin creatinine ratio (ACR) compared with controls. Independent of obstetric history, in both controls and women with a history of PE respectively, GFR (r=0.19, p=0.17 and r=0.12, p=0.29) and albumin creatinine ratio (r=0.07, p=0.62 and r=0.06 p=0.57) did not correlate with FMD.

CONCLUSION

At least 4years after pregnancy, women with a history of PE demonstrated decreased flow mediated dilatation when compared to healthy parous controls. In this study, decreased flow mediated dilation however did not coincide with decreased kidney function.

Coronary endothelial function is better in healthy premenopausal women than in healthy older postmenopausal women and men

BACKGROUND

Premenopausal women have fewer cardiovascular disease (CVD) events than postmenopausal women and age-matched men, but the reasons are not fully understood. Coronary endothelial function (CEF), a barometer of coronary vascular health, promises important insights into age and sex differences in atherosclerotic CVD risk, but has not been well characterized in healthy individuals because of the invasive nature of conventional CEF measurements. Recently developed magnetic resonance imaging (MRI) methods were used to quantify CEF (coronary area and flow changes in response to isometric handgrip exercise (IHE), an endothelial-dependent stressor) to test the hypothesis that healthy women have better CEF compared to men particularly at a younger age.

METHODS

The study participants were 50 healthy women and men with no history of coronary artery disease (CAD) or traditional CV risk factors and Agatston coronary calcium score (on prior CT) <10 for those ≥ 50 years. Coronary cross-sectional area (CSA) measurements and flow-velocity encoded images (CBF) were obtained at baseline and during continuous IHE using 3T breath-hold cine MRI-IHE. CEF (%change in CSA and CBF with IHE) comparisons were made according to age and sex, and all women ≥50 years were post-menopausal.

RESULTS

In the overall population, there were no differences in CEF between men and women. However, when stratified by age and sex the mean changes in CSA and CBF during IHE were higher in younger premenopausal women than older postmenopausal women (%CSA: 15.2±10.6% vs. 7.0±6.8%, p = 0.03 and %CBF: 59.0±37.0% vs. 30.5±24.5% p = 0.02). CBF change was also nearly two-fold better in premenopausal women than age-matched men (59.0±37.0% vs. 33.6±12.3%, p = 0.03).

CONCLUSIONS

Premenopausal women have nearly two-fold better mean CEF compared to postmenopausal women. CEF, measured by CBF change is also better in premenopausal women than age-matched men but there are no sex differences in CEF after menopause. Fundamental age and sex differences in CEF exist and may contribute to differences in the development and clinical manifestations of atherosclerotic CVD, and guide future trials targeting sex-specific mechanisms of atherogenesis.

Associations between parameters of flow-mediated vasodilatation obtained by continuous measurement approaches and the presence of coronary artery disease and the severity of coronary atherosclerosis

We investigated the associations between the parameters of flow-mediated vasodilatation (FMD) obtained by continuous measurement approaches and the presence of coronary artery disease (CAD) and the severity of coronary atherosclerosis. The subjects consisted of 282 consecutive patients who underwent coronary angiography (CAG) and in whom we could measure FMD. Using continuous measurement approaches, we measured FMD as the magnitude of the percentage change from brachial artery diameter from baseline to peak (bFMD), the maximum FMD rate calculated as the maximal slope of dilation (FMD-MDR), and the integrated FMD response calculated as the area under the dilation curve during the 60- and 120 s dilation periods (FMD-AUC60 and FMD-AUC120). We divided the patients into two groups, the CAD group and the non-CAD group, and defined the severity of coronary atherosclerosis according to the Gensini score. The CAD group showed significantly lower %FMD, FMD-MDR, FMD-AUC60, and FMD-AUC120. Gender, smoking, dyslipidemia (DL), and diabetes mellitus (DM), in addition to FMD-AUC120, were identified as significant independent variables that predicted the presence of CAD by a multivariate logistic regression. In addition, a multiple regression analysis indicated that gender, DL, and hypertension, in addition to FMD-AUC120, were predictors of the Gensini score. Finally, we defined the cutoff value of FMD-AUC120 for the prediction of CAD in all patients as 11.1 (sensitivity 0.582, specificity 0.652) by a receiver-operating characteristic (ROC) curve analysis. In conclusion, FMD-AUC120 as assessed by continuous measurement approaches may be a superior marker for evaluating the presence of CAD and the severity of coronary atherosclerosis.

Sex differences in vascular endothelial function and health in humans: impacts of exercise

NEW FINDINGS

What is the topic of this review? This brief review discusses potential sex differences in arterial function across the age span, with special emphasis on the effects of oestrogen and testosterone on the vascular endothelium. What advances does it highlight? We discuss the relationship between the impacts of sex hormones on arterial function and health in the context of epidemiological evidence pertaining to the menopause and ageing. Studies performed in humans are emphasized, alongside insights from animal studies. Findings suggest that the combination of exercise and hormone administration should be potentially synergistic or additive in humans. This brief review presents historical evidence for the purported impacts of male and female sex hormones on the vasculature in humans, including effects on macro- and microvascular function and health. Impacts of ageing on hormonal changes and arterial function are considered in the context of the menopause. Physiological data are presented alongside clinical outcomes from large trials, in an attempt to rationalize disparate findings along the bench-to-bedside continuum. Finally, the theoretical likelihood that exercise and hormone treatment may induce synergistic and/or additive vascular adaptations is developed in the context of recent laboratory studies that have compared male and female responses to training. Differences between men and women in terms of the impact of age and cardiorespiratory fitness on endothelial function are addressed. Ultimately, this review highlights the paucity of high-quality and compelling evidence regarding the fundamental impact, in humans, of sex differences on arterial function and the moderating impacts of exercise on arterial function, adaptation and health at different ages in either sex.

Differences in Vascular Reactivity Between Men and Women

The purpose of this study was to compare the gender and age-related differences in vascular reactivity in healthy men and women across a wide age range. Fifty-seven men and 61 women between 20 and 89 years of age, free of cardiovascular disease and risk factors, were categorized into younger (20-39 years), middle-aged (40-59 years), and older (60-89 years) age groups. Subjects were characterized on body weight and height, body mass index (BMI), and calf blood flow under resting, postocclusive reactive hyperemic (PORH), and maximal hyperemic conditions in the lower extremity with use of venous occlusion mercury strain-gauge plethysmography. Similar baseline characteristics were observed among age groups, whereas men had greater body weight (p<0.05), higher BMI values (p<0.05), and a trend toward higher ankle-brachial index (ABI) values (p=0.054) than women. While calf blood flow measurements were similar for men and women at rest and at maximal hyperemic conditions, women had a greater percentage change in calf blood flow from rest to PORH than men (p=0.046). After adjusting for body weight, BMI, and ABI, the percentage change in calf blood flow from rest to PORH was no longer significantly higher in the women (p>0.05). Furthermore, the percentage change in calf blood flow from rest to PORH was negatively related to body weight ( r = -0.30, p<0.01) and to BMI ( r = -0.26, p<0.01) in the men and women. No differences (p>0.05) in the calf blood flow measures were observed among the age groups. In a healthy cohort free of cardiovascular disease, increased BMI accounted for poorer vascular reactivity in men compared to women regardless of age.

Passive leg movement-induced vasodilation in women: the impact of age

Passive leg movement (PLM), an assessment of predominantly nitric oxide-dependent vasodilation, is decreased with age and cannot be augmented by posture-induced increases in femoral perfusion pressure in older men. However, this novel method of assessing vascular function has yet to be used to evaluate alterations in nitric oxide-dependent vasodilation with age in females. PLM was performed in 10 young (20 ± 1 yr) and 10 old (73 ± 2 yr) women in both the supine and upright-seated postures, whereas central and peripheral hemodynamic measurements were acquired second by second using noninvasive techniques (finger photoplethysmography and Doppler ultrasound, respectively). The heart rate response to PLM was attenuated in the old compared with the young in both the supine (young, 10 ± 1; and old, 5 ± 1 beats/min; P < 0.05) and upright-seated posture (young, 10 ± 2; and old, 5 ± 1 beats/min; P < 0.05), leading to a blunted cardiac output response in the old in the upright-seated posture (young, 1.0 ± 0.2; and old, 0.3 ± 0.1 l/min; P < 0.05). The PLM-induced peak change in leg vascular conductance was lower in the old compared with the young in both postures (young supine, 5.7 ± 0.5; old supine, 2.6 ± 0.3; young upright, 9.2 ± 0.7; and old upright, 2.2 ± 0.4 ml·min(-1)·mmHg(-1); P < 0.05) and was significantly augmented by the upright-seated posture in the young only, revealing a vasodilatory reserve capacity in the young (3.5 ± 0.6 ml·min(-1)·mmHg(-1), P < 0.05) that was absent in the old (-0.5 ± 0.3 ml·min(-1)·mmHg(-1), P = 0.18). These data support previous literature demonstrating attenuated PLM-induced vasodilation with age and extend these findings to include the female population, thus bolstering the utility of PLM as a novel assessment of vascular function across the life span in humans.

Diabetes and menopause aggravate age-dependent deterioration in arterial stiffness

OBJECTIVE

The present study was designed to evaluate the effects of menopause status and diabetes on arterial stiffness, metabolic parameters, and inflammatory parameters in premenopausal and postmenopausal women with and without type 2 diabetes mellitus.

METHODS

In the present study, 186 women were divided into three groups: group 1 includes 42 premenopausal women without type 2 diabetes mellitus, group 2 includes 85 postmenopausal women without diabetes, and group 3 includes 59 postmenopausal women with diabetes. Blood glucose, hemoglobin A1c, insulin, lipids, C-reactive protein, homeostasis model assessment-insulin resistance, aldosterone, and renin were measured. Pulse wave velocity (PWV) and augmentation index (AI) were determined using SphygmoCor (version 7.1; AtCor Medical, Sydney, Australia).

RESULTS

PWV and AI values increased from group 1 to group 3 in a continuous fashion. Postmenopausal women with and without diabetes exhibited significantly increased AI compared with premenopausal women without diabetes (P < 0.0001 and P < 0.0001, respectively). PWV was significantly higher in postmenopausal women with diabetes mellitus than in premenopausal and postmenopausal women without diabetes mellitus (P = 0.007 and P = 0.002, respectively).

CONCLUSIONS

Postmenopausal women without diabetes have significantly higher AI compared with premenopausal women without type 2 diabetes mellitus. The combination of diabetes and postmenopause status is associated with further deterioration of AI and PWV independently of age, body mass index, and other cardiovascular risk factors.

Task force on: 'Early markers of atherosclerosis: influence of age and sex'

Atherosclerosis and its complications are the most important causes of death all over the world, especially in Western countries. Diet habits, modern stress life, smoking, sedentary way of life and an involvement of genetic pattern of individuals lead to a sure degeneration of quality of life increasing the risk of atherosclerosis development. For this reason, the main purpose of actual medicine is to identify all the markers that could allow the physicians to evaluate the first moments of the development of this dangerous pathological process. The aim is to reduce the speed of its evolution, trying to delay indefinitely the risk coming from the morphological alterations of the vessels. 'Endothelium function' could allow physicians to detect the first moment of the natural history of atherosclerosis process. Its impairment is the first step in the degeneration of vascular structures. Many methods [flow-mediated vasodilatation (FMD); antero-posterior abdominal aorta diameter (APAO); intima-media thickness of the common carotid artery (CCA-IMT); arterial stiffness; and so on] try to evaluate its function, but many limitations come from general population characteristics. A standardization of the methods should take into account individuals' peculiarities. Two elements, not modifiable, should be taken into account for vascular evaluation: age and sex. The aim of this review is to outline the linkage among age, sex and instrumental evaluation of patients considered for a noninvasive assessment of their cardiovascular risk profile.

The perimenopausal woman: endocrinology and management

This review focuses on the endocrine and physiological features of the transition to menopause, known as the menopausal transition or the perimenopause. The updated 2011 Stages of Reproductive Aging workshop (STRAW) system is presented with a discussion of the new subdivisions within stages -3 (late reproductive age) and +1 (postmenopause) and incorporation of FSH and other biomarkers in the supportive criteria. Ovarian follicle reserve and ovarian follicle dynamics are also discussed in terms of the changes that occur with reproductive aging, and the dramatic effect these changes have on the hypothalamic-pituitary-gonadal feedback system. Topics include the disruption of normal ovulatory function and related hormone secretion patterns, abnormal uterine bleeding, and the changes that occur in bone and the cardiovascular system. The review concludes with a discussion of management strategies. This article is part of a Special Issue entitled 'Menopause'.

Role of aromatase in sex-specific cerebrovascular endothelial function in mice

Stroke risk and outcome are strongly modified by estrogen. In addition to ovaries, estrogen is produced locally in peripheral tissue by the enzyme aromatase, and extragonadal synthesis becomes the major source of estrogen after menopause. Aromatase gene deletion in female mice exacerbates ischemic brain damage after stroke. However, it is not clear which cell type is responsible for this effect, since aromatase is expressed in multiple cell types, including cerebrovascular endothelium. We tested the hypothesis that cerebrovascular aromatase contributes to sex differences in cerebrovascular endothelial function. Cerebrocortical microvascular responses to the endothelium-dependent vasodilator ACh were compared between male and female wild-type (WT) and aromatase knockout (ArKO) mice by measuring laser-Doppler perfusion in vivo through a closed cranial window. Additional studies were performed in WT mice treated with the aromatase inhibitor fadrozole or vehicle. WT female mice had significantly greater responses to ACh compared with WT males (P < 0.001), which was associated with higher aromatase expression in female compared with male cerebral vessels (P < 0.05). ACh responses were significantly lower in ArKO compared with WT females (P < 0.05) and in WT females treated with fadrozole versus vehicle (P < 0.001). Conversely, ACh responses were significantly higher in ArKO versus WT males (P < 0.05). Levels of phosphorylated endothelial nitric oxide synthase (eNOS) were lower in ArKO versus WT female brains, but were not altered by aromatase deletion in males. We conclude that cerebrovascular endothelial aromatase plays an important and sexually dimorphic role in cerebrovascular function and that aromatase inhibitors in clinical use may have cardiovascular consequences in both males and females.

Differential influence of distinct components of increased blood pressure on cardiovascular outcomes: from the atherosclerosis risk in communities study

Elevation in blood pressure (BP) increases risk for all cardiovascular events. Nevertheless, the extent to which different indices of BP elevation may be associated to varying degrees with different cardiovascular outcomes remains unclear. We studied 13340 participants (aged 54 ± 6 years, 56% women and 27% black) of the Atherosclerosis Risk in Communities Study who were free of baseline cardiovascular disease. We used Cox proportional hazards models to compare the relative contributions of systolic BP, diastolic BP, pulse pressure, and mean arterial pressure to risk for coronary heart disease, heart failure, stroke, and all-cause mortality. For each multivariable-adjusted model, the largest area under the receiver-operating curve (AUC) and smallest -2 log-likelihood values were used to identify BP measures with the greatest contribution to risk prediction for each outcome. A total of 2095 coronary heart disease events, 1669 heart failure events, 771 stroke events, and 3016 deaths occurred during 18 ± 5 years of follow-up. In multivariable analyses adjusting for traditional cardiovascular risk factors, the BP measures with the greatest risk contributions were the following: systolic BP for coronary heart disease (AUC=0.74); pulse pressure for heart failure (AUC=0.79); systolic BP for stroke (AUC=0.74); and pulse pressure for all-cause mortality (AUC=0.74). With few exceptions, results were similar in analyses stratified by age, sex, and race. Our data indicate that distinct BP components contribute variably to risk for different cardiovascular outcomes.

Correlation between endothelial dysfunction, Rho-associated protein kinase activity, C-reactive protein and obstructive sleep apnoea syndrome in male patients

OBJECTIVE

This study investigated the association between obstructive sleep apnoea syndrome (OSAS) and flow-mediated dilatation (FMD), Rho-associated protein kinase (ROCK) activity, and C-reactive protein (CRP) concentrations in male patients.

METHODS

Consecutive patients with symptoms suggestive of OSAS were recruited and divided into non-OSAS (n = 18) and OSAS (n = 32) groups. FMD was measured in the brachial artery; blood samples were taken to measure ROCK activity and CRP concentrations.

RESULTS

ROCK activity and CRP concentrations were significantly higher, and FMD was significantly lower, in the OSAS group than in the non-OSAS group. There was a correlation between ROCK activity and FMD. In stepwise multiple regression analyses, the proportion of sleep time spent with an oxygen saturation < 90% was a significant determinant of ROCK activity, while body mass index was the only significant determinant of CRP concentration. The oxygen desaturation index was a significant determinant of FMD.

CONCLUSIONS

OSAS increased ROCK activity and was a major determinant of endothelial dysfunction.

Impact of acute exercise on brachial artery flow-mediated dilatation in young healthy people

Background

Although chronic effects of exercise on endothelial function are established, the impact of acute exercise on flow-mediated dilatation (FMD) of brachial artery has not been elucidated yet.

Methods

Eighty-six young healthy volunteers were prospectively enrolled from January 2011 to December 2011. The subjects completed FMD tests at rest and immediately after treadmill exercise test. Primary outcome was the impact of acute exercise on FMD, measured by the difference of FMD before and after exercise. Secondary outcomes were the relationship of gender and exercise habit with FMD.

Results

Seventy-four subjects who met the eligibility criteria were included for analysis. Thirty-five (47.3%) were male, and the mean age was 22.7±2.7 years. FMD was reduced after exercise (8.98±4.69 to 7.51±4.03%; P=0.017) and the reduction was found in female group (10.36±5.26 to 7.62±3.71%; P=0.002) but not in male group. Post-exercise FMD was significantly impaired in subjects who did not exercise regularly (6.92±3.13% versus 8.95±5.33%; P=0.003). The decrease of FMD after exercise was greater in female group (−2.75±5.28% versus 0.27±3.24%; P=0.003) and was associated with exercise habit (β=2.532; P=0.027).

Conclusions

In healthy young subjects, FMD was reduced after a bout of acute exercise. The impact of acute exercise showed significant differences according to gender and exercise habit. FMD impairment after acute exercise was observed in females and subjects without regular exercise.

Vascular endothelial function is not related to serum uric acid in healthy adults

Background

Some experimental evidence suggests that uric acid impairs endothelial function. It is controversial if high uric acid levels and impaired endothelial function are related in healthy adults. In addition, the effect of uric acid on endothelial cells (ECs) of humans is unexplored.

Methods

Data of 107 healthy adult volunteers were analyzed. The association between serum uric acid and endothelial-dependant dilation (EDD) and endothelial-independent dilation (EID) was evaluated by linear regression models. We also examined the relations between uric acid and systemic and cellular markers of inflammation and oxidative stress in all or subsets of participants.

Results

Uric acid levels and EDD were not related in unadjusted or adjusted models. There was a significant negative correlation between uric acid and EID in the pooled sample (r = −0.34, P = 0.005). This correlation remained significant after adjusting for demographics (P = 0.04) and was attenuated after adjusting for other cardiac risk factors (P = 0.12). Higher serum uric acid levels were found to correlate significantly with C-reactive protein (CRP) (r = 0.31, P = 0.002). Serum uric acid levels were not associated with brachial artery EC nuclear factor-κB (NF-κB) p65 or NADPH oxidase p47^phox expression or with nitrotyrosine staining, but were inversely associated with EC manganese superoxide dismutase (MnSOD) expression (r = −0.5, P = 0.01, n = 25).

Conclusion

Elevated serum uric acid is not associated with endothelial dysfunction among healthy adults, but is inversely related to EID and EC MnSOD, and positively related to systemic inflammation. These findings may have implications for cardiovascular risk in healthy adults.

Lipids, menopause, and early atherosclerosis in Study of Women's Health Across the Nation Heart women

OBJECTIVE

The risk of cardiovascular disease increases after menopause. Recent evidence suggests that it is possible for high-density lipoprotein (HDL) to become proatherogenic or dysfunctional in certain situations. Our objective was to evaluate whether the relationship of HDL cholesterol (HDL-C) to subclinical cardiovascular disease differed across the menopausal transition, which would provide insight for this increased risk.

METHODS

Aortic calcification (AC), coronary artery calcification (CAC), carotid plaque, and intima media thickness (IMT) were measured in an ancillary study of the Study of Women's Health Across the Nation. Women not using hormone therapy were stratified into premenopausal or early perimenopausal (Pre/EP, n=316) and late perimenopausal or postmenopausal (LP/Post, n=224).

RESULTS

The inverse relationship of HDL-C to subclinical atherosclerosis measures among Pre/EP women was weaker or reversed among LP/Post women, adjusted for age, site, race, systolic blood pressure, glucose, body mass index, smoking, menopause status, and low-density lipoprotein cholesterol. Specifically, multivariable modeling demonstrated an inverse association between HDL-C level and AC and IMT among Pre/EP women; however, the protective effect of HDL-C for AC, left main CAC, carotid plaque, and IMT was not seen in LP/Post women. In a small subset (n=53), LP/Post women had more total and small HDL particles, higher triglyceride levels, and more total low-density lipoprotein particles compared with Pre/EP women (P<0.05).

CONCLUSIONS

These results suggest that the protective effect of HDL may be diminished as women transition in menopause. Future studies should examine whether this may be due to changes in HDL size, functionality, or related changes in other lipids or lipoproteins.

Effect of local and remote ischemic preconditioning on endothelial function in young people and healthy or hypertensive elderly people

To verify whether age affects remote preconditioning, we compared healthy young people (mean age = 28.0 years, SD: 7.2), healthy elderly people (age = 69.2 years, SD: 5.0), and hypertensive elderly people (group 3, age = 72.8 years, SD: 3.9). Each group included 10 participants. The flow-mediated-dilation (FMD) was measured after local (same arm) and remote (leg) ischemic preconditioning. Healthy elderly people had the greatest increase of FMD after ischemic preconditioning compared to baseline (173% after local and 181% after remote preconditioning) and young participants the smallest increase (77% after local and 69% after remote preconditioning) while hypertensive elderly had an intermediate increase (P for comparison across groups: 0.347 for local and 0.064 for remote preconditioning). However, absolute values of FMD after preconditioning were much lower in elderly hypertensive than in healthy young adults. Remote preconditioning increases endothelial reactivity in healthy and hypertensive elderly. The potential clinical relevance of this finding deserves consideration.

The menopausal transition and cardiovascular risk

The incidence of cardiovascular disease, which is the leading single cause of death among women, increases substantially after menopause. This may be related to adverse changes in cardiovascular risk factors that occur during the menopausal transition. Proatherogenic changes in lipid and apolipoprotein profiles seem to be specifically related to ovarian aging; unfavorable changes in other cardiovascular risk factors may be influenced more by chronologic aging. Whether these changes are due to aging or to menopause itself, increased attention to risk factor modification in the pre- and perimenopausal years will help reduce future cardiovascular disease risk among women.

Lectin-like oxidized low-density lipoprotein receptor-1 modulates endothelial apoptosis in obstructive sleep apnea

BACKGROUND

Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) is the major receptor for oxidized low-density lipoprotein in endothelial cells, and its expression is enhanced in proatherogenic settings. The objective of this study was to investigate the association between LOX-1 in freshly harvested human venous endothelial cells and apoptotic circulating endothelial cells in patients with obstructive sleep apnea (OSA).

METHODS

We conducted a prospective, interventional study of 38 patients with newly diagnosed OSA free of disease and 12 healthy control subjects. Plasma LOX-1 (pLOX-1) levels were measured using a commercially available enzyme-linked immunosorbent assay. Protein expression of LOX-1 was quantified by immunofluorescence in freshly harvested venous endothelial cells before and after 8 weeks of continuous positive airway pressure (CPAP) therapy. Circulating apoptotic endothelial cells (CD146(+), CD45(-), and CD31(1)) were assessed concomitantly by flow cytometry.

RESULTS

pLOX-1 levels were higher in subjects with OSA than in control subjects (326.9 ± 267.1 pg/mL and 141.1 ± 138.6 g/mL, respectively; P = .004). Patients with OSA showed a threefold increase in baseline endothelial expression of LOX-1 relative to control subjects. CPAP therapy resulted in a significant decrease in endothelial LOX-1 expression only in CPAP-adherent patients. Circulating apoptotic endothelial cells correlated directly with baseline expression of LOX-1 (R(2) = 0.32, P = .01) after adjustment for age, BMI, and waist to hip ratio.

CONCLUSIONS

Increased expression of LOX-1 in vivo is associated with endothelial apoptosis. Adherence to CPAP therapy may reverse these derangements.

Endothelial biology in the post-menopausal obese woman

Women generally have a reduced risk of cardiovascular disease (CVD). However, this protection of gender diminishes rapidly after menopause and with advancing age, particularly in obese women. Alterations in vascular function are thought to a key early step in the development of atherosclerosis. In this review, we will describe the features of endothelial dysfunction in the post-menopausal obese female and discuss the interplay of aging, estrogen withdrawal, and obesity. The objectives include (1) a review of endothelial biology and endothelial dysfunction, and (2) a discussion how the endothelial function is altered in the context of aging, hormonal changes and insulin resistance. The clinical consequences of endothelial dysfunction and CVD will also be reviewed.

Sex, clinical symptoms, and angiographic findings in patients with diabetes mellitus and coronary artery disease (from the Bypass Angioplasty Revascularization Investigation [BARI] 2 Diabetes trial)

Previous studies have reported differences in presenting symptoms and angiographic characteristics between women and men undergoing evaluation for suspected coronary artery disease (CAD). We examined the relation between symptoms and extent of CAD in patients with type 2 diabetes mellitus and known CAD enrolled in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial. Of 1,775 patients (533 women, 30%, and 1,242 men, 70%), women were more likely than men to have angina (65% vs 56%, p <0.001) or an atypical angina/anginal equivalent (71% vs 58%, p <0.001). More women reported unstable angina (17% vs 13%, p = 0.047) or were in a higher Canadian Cardiology Society class compared to men (Canadian Cardiology Society classes II to IV 78% vs 68%, p = 0.002). Fewer women than men had no symptoms (14% vs 22%, p <0.001). Women had a lower mean myocardial jeopardy index (42.5 ± 24.3 vs 47.9 ± 24.3, p <0.001), smaller number of total significant lesions (2.3 ± 1.7 vs 2.7 ± 1.8, p <0.001), and fewer jeopardized left ventricular regions (p <0.001 for distribution) or long-term occlusions (29% vs 42%, p <0.001). After adjustment for relevant covariates, the odds of having CAD symptoms were still higher in women than men (odds ratio for angina 1.31, 95% confidence interval 1.02 to 1.69; odds ratio for atypical angina 1.52, 95% confidence interval 1.17 to 1.96). In conclusion, in a high-risk group of patients with known CAD and diabetes mellitus, women were more symptomatic than men but had less obstructive CAD. These data suggest that factors other than epicardial CAD severity influence symptom presentation in women in this population.

Modification of vascular function after handgrip exercise training in 73- to 90-yr-old men

PURPOSE

To examine the influence of a unilateral exercise training protocol on brachial artery reactivity (BAR) in 12 men (aged 81 +/- 5 yr).

METHODS

Brachial artery diameters and blood flow parameters were assessed, in both arms, using high-resolution ultrasonography, before and after 5 min of forearm occlusion, before and at the end of each week of a 4-wk training program. Training consisted of a unilateral handgrip training protocol (nondominant arm) at 60% of maximal voluntary handgrip strength, performed for 4 wk, 4 d x wk(-1), 20 min per session, and a cadence of one contraction per 4 s.

RESULTS

After training, handgrip strength increased 6.2% (baseline = 32.4 +/- 7.0 kg vs week 4 = 34.4 +/- 6.7 kg) in the trained arm only but failed to reach statistical significance (P = 0.10). No statistical changes were observed for blood pressure or resting HR. In contrast, BAR increased 45% (Pre = 2.9% vs Post = 4.1%, P = 0.05) in the trained arm only. Improvements in BAR were observed after the second week of training, without significant changes in the main vasodilatory trigger, defined as the relevant shear stimulus after forearm occlusion (P > 0.05).

CONCLUSIONS

These data indicate that a localized short-term exercise program results in significant improvements in vascular function in the trained arm of elderly men compared with the control arm. Furthermore, the findings indicate a statistically significant increase in BAR at the end of the second week of training, despite a similar trigger for dilation versus before training.

Reduced residual renal function is associated with endothelial dysfunction in patients receiving peritoneal dialysis

BACKGROUND

Endothelial dysfunction, which contributes to atherosclerosis and arteriosclerosis, commonly accompanies end-stage renal disease (ESRD). However, little is known about the role of residual renal function (RRF) in endothelial protection in ESRD patients. This study aimed to investigate the relationship between endothelial function and RRF in patients undergoing peritoneal dialysis (PD).

METHODS

This was a cross-sectional study involving 72 prevalent PD patients. Demographic and clinical data were recorded and residual glomerular filtration rate (GFR), Kt/V urea, and serum concentrations of inflammatory markers were measured. Endothelial function was assessed by brachial artery endothelium-dependent vasodilation [flow-mediated dilation (FMD)] to reactive hyperemia following 5 minutes of forearm ischemia.

RESULTS

In patients with FMD% above the median value (FMD > 2.41%), residual GFR was significantly higher compared to that in patients with FMD% below the median [1.50 (0 - 9.64) vs 0.48 (0 - 3.89) mL/min/1.73 m(2), P = 0.026]. Correlation analyses revealed that residual GFR (ρ = 0.381, P = 0.001) and total Kt/V urea (γ = 0.408, P < 0.001) were positively correlated with FMD%, whereas PD duration (γ = -0.351, P = 0.003), high-sensitivity C-reactive protein (ρ = -0.345, P = 0.003), pulse pressure (γ = -0.341, P = 0.003), and age (γ = -0.403, P < 0.001) were inversely correlated with FMD%. In contrast, there was no correlation between peritoneal Kt/V urea and FMD%. In multivariate linear regression analysis adjusted for these factors, residual GFR was found to be an independent determinant of FMD% (β = 0.317, P = 0.017).

CONCLUSION

This study shows that RRF is independently associated with endothelial dysfunction in ESRD patients on PD, suggesting that RRF may contribute to endothelial protection in these patients.

Long-term exercise training does not alter brachial and femoral artery vasomotor function and endothelial phenotype in healthy pigs

Although the beneficial effects of exercise training on conduit artery endothelial function are well-established in animals and humans with compromised basal function, whether exercise exerts favorable effects on a healthy endothelium is inconclusive. We sought to determine whether long-term exercise training enhances endothelial function in peripheral conduit arteries of healthy pigs. Using a retrospective analysis of data collected in our laboratory (n = 127), we compared in vitro brachial and femoral artery endothelium-dependent and -independent relaxation between a group of pigs that exercise-trained for 16-20 wk and a group that remained sedentary. No differences in vasomotor function were found between the 2 groups (P > 0.05). Additionally, in a subset of pigs (n = 16), expression levels of 18 proteins that are typically associated with the atherosclerotic process were measured by immunoblot analysis of endothelial cell scrapes obtained from the brachial and femoral arteries. We found no differences (P > 0.05) in endothelial gene expression between these exercise-trained and sedentary healthy pigs. These results indicate that pigs exhibiting the classic training-induced adaptations do not demonstrate enhanced endothelium-dependent dilation nor reveal a more atheroprotected endothelial cell phenotype in their brachial and femoral arteries than their sedentary but otherwise healthy counterparts.

Pulse wave amplitude is associated with brachial artery diameter: implications for gender differences in microvascular function

The ratio of pulse wave amplitude (PWA) during reactive hyperemia compared to baseline as measured by peripheral arterial tonometry (PAT) is a non-invasive measure of microvascular endothelial function referred to as the pulse wave amplitude reactive hyperemia index (PWA-RHI). Whether upstream conduit vessel structure may affect downstream resistance vessel PWA has not been clearly examined. We tested the hypothesis that digital PWA is influenced by brachial artery diameter (BAD) and that this association would influence comparison of PWA-RHI between genders. Measures of vascular structure and microvascular function were carried out in 115 patients varying in cardiovascular risk profiles (average age 57 years, male n = 79, CAD n = 43). PWA was assessed using plethysmography at baseline and following 5 minutes of brachial artery occlusion. BAD was assessed using high-resolution ultrasonography. Results : There was a negative association between BAD and PWA-RHI ( r = -0.34, p < 0.05). Women had greater PWA-RHI and smaller BAD compared with men (p < 0.05). When co-varying for BAD, there were no longer gender differences in PWA-RHI. Moreover, when a sub-group of men and women without CAD (n = 40), matched for BAD, were examined, there were no gender differences in PWA-RHI. In conclusion, PWA-RHI obtained from PAT is associated with BAD. Studies examining gender differences in microvascular endothelial function with PAT may need to correct for BAD as a potential confounder.

Noninvasive assessment of subclinical atherosclerosis in children and adolescents: recommendations for standard assessment for clinical research: a scientific statement from the American Heart Association

Deterioration in endothelial function and arterial stiffness are early events in the development of cardiovascular diseases. In adults, noninvasive measures of atherosclerosis have become established as valid and reliable tools for refining cardiovascular risk to target individuals who need early intervention. With limited pediatric data, the use of these techniques in children and adolescents largely has been reserved for research purposes. Therefore, this scientific statement was written to (1) review the current literature on the noninvasive assessment of atherosclerosis in children and adolescents, (2) make recommendations for the standardization of these tools for research, and (3) stimulate further research with a goal of developing valid and reliable techniques with normative data for noninvasive clinical evaluation of atherosclerosis in pediatric patients. Precise and reliable noninvasive tests for atherosclerosis in youth will improve our ability to estimate future risk for heart attack and stroke. Currently, large longitudinal studies of cardiovascular risk factors in youth, such as the Bogalusa and Muscatine studies, lack sufficient adult subjects experiencing hard outcomes, such as heart attack and stroke, to produce meaningful risk scores like those developed from Framingham data.

Impact of age, sex, and exercise on brachial artery flow-mediated dilatation

Flow-mediated dilatation (%FMD), an index of nitric oxide (NO)-mediated vasodilator function, is regarded as a surrogate marker of cardiovascular disease. Aging is associated with endothelial dysfunction, but underlying sex-related differences may exist and the effects of fitness and exercise on endothelial dysfunction in men (M) and women (W) are poorly understood. We compared %FMD of the brachial artery in 18 young [Y, 26 +/- 1 yr; 9 M and 9 W], 12 older fit (OF, 57 +/- 2 yr; 6 M and 6 W), and 16 older sedentary (OS, 59 +/- 2 yr; 8 M and 8 W) subjects. Glyceryl trinitrate (GTN) administration was used to assess endothelium-independent vasodilatation, and the FMD-to-GTN ratio was calculated to characterize NO dilator function in the context of smooth muscle cell sensitivity. Brachial %FMD in Y (7.1 +/- 0.8%) was significantly higher compared with OS (4.8 +/- 0.7%, P < 0.05), but not OF (6.4 +/- 0.7%). Differences between Y and OS subjects were due primarily to lower FMD in the OS women (4.3 +/- 0.6%). OS women exhibited significantly lower FMD-to-GTN ratios compared with Y (P < 0.05) and OF women (P < 0.05), whereas these differences were not apparent in men. Exercise training improved brachial artery NO dilator function (FMD-to-GTN ratio) after 24 wk (P < 0.05) in OS women, but not men. These findings indicate that maintaining a high level of fitness, or undertaking exercise training, prevents the age-related decline in the brachial artery vasodilator function evident in women. In OS men, who had relatively preserved NO dilator function, no training adaptations were observed. This study has potential implications for the prevention of conduit artery endothelial dysfunction in men and women.

Brachial artery diameter is related to cardiovascular risk factors and intima-media thickness

BACKGROUND

Previous reports showed inconsistent results about the potential role of flow-mediated dilatation (FMD) in cardiovascular(CV) risk prediction. Few data are available about the role of nitroglycerin-mediated dilatation (NMD), but recently, brachial artery diameter(BAD) appeared to have predictive value in CV risk prediction.We determined the relation of FMD, BAD and NMD with known CV risk factors and intima-media thickness (IMT), a well-established surrogate marker of atherosclerosis, in a community-based population, the Nijmegen Biomedical Study (NBS).

MATERIALS AND METHODS

FMD, BAD and NMD were measured in the brachial, and IMT in the common carotid artery ultrasononically in 337 participants, aged 50-70 years. Traditional clinical and biochemical parameters were determined.

RESULTS

Both FMD and NMD were not correlated with most CV risk factors or prevalent CVD. However, both IMT and BAD did show significant correlations with CV risk factors. In accordance, both IMT and BAD were significantly correlated with prevalent CVD (r=0.62 and r=-0.37, respectively) . Furthermore, FMD was not correlated with IMT and did hardly (R2=1.1%) improve the prediction of IMT by CV risk factors in regression analysis. However, both BAD and NMD did correlate with IMT (r=-0.29 and r=0.25, respectively).

CONCLUSION

In our study, FMD and NMD were not related to known CV risk factors and prevalent CVD, and FMD was not correlated with IMT, a surrogate marker of atherosclerosis. Most intriguingly, BAD was significantly correlated with some CV risk factors, prevalent CVD and IMT. So, BAD is a potential valuable tool in CV risk prediction in middle-aged low-risk populations, whereas FMD is not.

The relationships of cardiovascular disease risk factors to flow-mediated dilatation in Japanese subjects free of cardiovascular disease

We examined the relationship of several cardiovascular disease (CVD) risk factors to flow-mediated vasodilatation of the brachial artery (FMD) and the clustering effect of risk factors on FMD in Japanese subjects free of CVD. In 819 Japanese subjects free of CVD (age 45+/-10 years, 611 men and 208 women), FMD correlated significantly with the Framingham risk points score (FRS) (r=-0.27, p<0.01). FMD was higher in subjects in the 1st tertile of the FRS range than in patients in either the 2nd or 3rd tertiles of the FRS range, but it was similar between the subjects in the 2nd and 3rd tertiles. FMD was found to have a significant independent negative correlation with age (beta=-0.19, p<0.01), gender (beta=-0.024, p<0.01) and smoking habit (beta=-0.08, p=0.02). In subjects >or=50 years of age, the FMD in men with one CVD risk factor, excluding smoking, was similar to that in men with no CVD risk factors. CVD risk factors did not attenuate FMD in women. Thus, in Japanese subjects free of CVD, FMD may be a useful marker of CVD risk, but it may not be a robust marker for endothelial damage related to clusters of CVD risk factors. Age, gender and smoking were independent variables related to the impairment of FMD, which therefore appears to be less applicable in subjects aged 50 or more, and especially in women. (Hypertens Res 2008; 31: 2019-2025).

Review: Endothelial dysfunction: A potential tool in gender related cardiovascular disease

The overwhelming importance of distinctive cardiovascular disease profile in women has stimulated enormous efforts to disclose its cause. In this review, we discuss vascular endothelium as a potential phenotypic marker for the genetic difference. As it is a potentially modifiable factor for cardiovascular disease, every effort should be made to detect it, either directly or indirectly, at the earliest in females who are at risk, so that the future cardiovascular events might be prevented.

Differences in muscle protein synthesis and anabolic signaling in the postabsorptive state and in response to food in 65-80 year old men and women

Women have less muscle than men but lose it more slowly during aging. To discover potential underlying mechanism(s) for this we evaluated the muscle protein synthesis process in postabsorptive conditions and during feeding in twenty-nine 65-80 year old men (n = 13) and women (n = 16). We discovered that the basal concentration of phosphorylated eEF2(Thr56) was approximately 40% less (P<0.05) and the basal rate of MPS was approximately 30% greater (P = 0.02) in women than in men; the basal concentrations of muscle phosphorylated Akt(Thr308), p70s6k(Thr389), eIF4E(Ser209), and eIF4E-BP1(Thr37/46) were not different between the sexes. Feeding increased (P<0.05) Akt(Thr308) and p70s6k(Thr389) phosphorylation to the same extent in men and women but increased (P<0.05) the phosphorylation of eIF4E(Ser209) and eIF4E-BP1(Thr37/46) in men only. Accordingly, feeding increased MPS in men (P<0.01) but not in women. The postabsorptive muscle mRNA concentrations for myoD and myostatin were not different between sexes; feeding doubled myoD mRNA (P<0.05) and halved that of myostatin (P<0.05) in both sexes. Thus, there is sexual dimorphism in MPS and its control in older adults; a greater basal rate of MPS, operating over most of the day may partially explain the slower loss of muscle in older women.

Effects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity

BACKGROUND

The effects of a very-low-carbohydrate, high-saturated-fat weight-loss diet (LC) on brachial artery flow-mediated dilatation (FMD) and markers of endothelial function are unknown.

OBJECTIVE

The effect of an LC on markers of endothelial function and cardiovascular disease (CVD) risk was compared with that of an isocaloric high-carbohydrate, low-saturated-fat diet (HC).

DESIGN

FMD and markers of endothelial function (n = 70) and CVD risk were measured before and after 8 wk of weight loss. Ninety-nine subjects aged 50.0 +/- 8.3 y with a body mass index (in kg/m2) of 33.7 +/- 4.1 completed the study.

RESULTS

Mean (+/-SD) FMD did not change significantly (P = 0.55) with either diet. Pulse wave velocity improved with both diets (P < 0.01). Endothelial markers, E- and P selectin, intracellular and cellular-adhesion molecule-1, tissue-type plasminogen activator, and plasminogen activator inhibitor-1 decreased (P < 0.001), with no diet effect. Adiponectin did not change significantly. More weight (P = 0.05 for diet x time interaction) and more abdominal fat mass (P = 0.05 for diet x time interaction) were lost with the LC than with the HC. LDL cholesterol decreased more with the HC than with the LC (P < 0.05, time x diet), and C-reactive protein decreased more with the HC than with the LC (P < 0.05 for diet x time interaction). Homocysteine increased more with the LC (P < 0.01 for diet x time interaction). Folate decreased with the LC and increased with the HC (P < 0.05, time; P < 0.001 for diet x time interaction).

CONCLUSION

An LC does not impair FMD. We observed beneficial effects of both diets on most of the CVD risk factors measured. This trial was registered with the Australian Clinical Trials Registry as ACTR N0 12606000203550.