Endothelium-dependent vasodilation and structural and functional changes in the cardiovascular system are dependent on age in healthy subjects

Effects of Greater Central Arterial Stiffness on Cardiovagal Baroreflex Sensitivity in Resistance-Trained Men

Background

Compared with age-matched untrained men, resistance-trained men who have undergone long duration training (> 2 years) at a high frequency (> 5 days/week) may be lower cardiovagal baroreflex sensitivity (BRS) because of central arterial stiffening. Therefore, the purpose of this study was to examine the effect of greater central arterial stiffness in resistance-trained men on cardiovagal BRS in a cross-sectional study to compare resistance-trained men with age-matched untrained men.

Methods

This cross-sectional study included resistance-trained men (n = 20; age: 22 ± 3; body mass index: 26.7 ± 2.2) and age-matched untrained men (control group: n = 20; age: 25 ± 2; body mass index: 23.7 ± 2.4). The β-stiffness index and arterial compliance were assessed at the right carotid artery using a combination of a brightness mode ultrasonography system for the carotid artery diameter and applanation tonometry for the carotid blood pressure. And, the cardiovagal BRS was estimated by the slope of the R–R interval and systolic blood pressure during Phase II and IV of Valsalva maneuver (VM). The participants maintained an expiratory mouth pressure of 40 mmHg for 15 s in the supine position.

Results

The β-Stiffness index was significantly higher in the resistance-trained group than in the control group (5.9 ± 1.4 vs. 4.4 ± 1.0 a.u., P < 0.01). In contrast, the resistance-trained group had significantly lower arterial compliance (0.15 ± 0.05 vs. 0.20 ± 0.04 mm²/mmHg, P < 0.01) and cardiovagal BRS during Phase IV of VM (9.0 ± 2.5 vs. 12.9 ± 5.4 ms/mmHg, P < 0.01) than the control group and. Moreover, cardiovagal BRS during Phase IV of VM was inversely and positively correlated with the β-stiffness index (r = − 0.59, P < 0.01) and arterial compliance (r = 0.64, P < 0.01), respectively.

Conclusion

Resistance-trained group had greater central arterial stiffness and lower cardiovagal BRS Phase IV compared with control group. Moreover, the central arterial stiffening was related to cardiovagal BRS Phase IV. These results suggest that greater central arterial stiffness in resistance-trained men may be associated with lower cardiovagal BRS.

Trial Registration University hospital Medical Information Network (UMIN) in Japan, UMIN000038116. Registered on September 27, 2019.

Vascular Inflammation and Oxidative Stress: Major Triggers for Cardiovascular Disease

Cardiovascular disease is a leading cause of death and reduced quality of life, proven by the latest data of the Global Burden of Disease Study, and is only gaining in prevalence worldwide. Clinical trials have identified chronic inflammatory disorders as cardiovascular risks, and recent research has revealed a contribution by various inflammatory cells to vascular oxidative stress. Atherosclerosis and cardiovascular disease are closely associated with inflammation, probably due to the close interaction of inflammation with oxidative stress. Classical therapies for inflammatory disorders have demonstrated protective effects in various models of cardiovascular disease; especially established drugs with pleiotropic immunomodulatory properties have proven beneficial cardiovascular effects; normalization of oxidative stress seems to be a common feature of these therapies. The close link between inflammation and redox balance was also supported by reports on aggravated inflammatory phenotype in the absence of antioxidant defense proteins (e.g., superoxide dismutases, heme oxygenase-1, and glutathione peroxidases) or overexpression of reactive oxygen species producing enzymes (e.g., NADPH oxidases). The value of immunomodulation for the treatment of cardiovascular disease was recently supported by large-scale clinical trials demonstrating reduced cardiovascular mortality in patients with established atherosclerotic disease when treated by highly specific anti-inflammatory therapies (e.g., using monoclonal antibodies against cytokines). Modern antidiabetic cardiovascular drugs (e.g., SGLT2 inhibitors, DPP-4 inhibitors, and GLP-1 analogs) seem to share these immunomodulatory properties and display potent antioxidant effects, all of which may explain their successful lowering of cardiovascular risk.

Resistance Training Augments Cerebral Blood Flow Pulsatility: Cross-Sectional Study

BACKGROUND

Increased central arterial stiffness and/or decreased compliance reduces buffer function and increases cerebral blood flow (CBF) pulsatility, which leads to increased cerebral microvascular damage, resulting in the augmentation of the risk of cerebrovascular diseases. Resistance-trained men showed higher central arterial stiffness and lower arterial compliance than age-matched, sedentary men. This study examined the effect of increased central arterial stiffness and/or decreased arterial compliance on CBF pulsatility.

METHODS

The study participants included 31 young healthy men (15 resistance-trained men, aged 21 ± 1 years; and 16 controls, aged 23 ± 1 years). β-Stiffness index and arterial compliance were measured in the right carotid artery as index of central arterial stiffness and compliance, respectively. The pulsatility index (PI) was measured in the middle cerebral artery as index of CBF pulsatility.

RESULTS

β-Stiffness index and PI were significantly higher in the resistance-trained group than in the control group (β-stiffness index: 5.3 ± 0.3 vs. 3.5 ± 0.3 a.u., P < 0.05, PI: 0.80 ± 0.02 vs. 0.70 ± 0.02, P < 0.05). The resistance-trained group showed significantly lower arterial compliance than the control group (0.16 ± 0.01 vs. 0.23 ± 0.01 mm2/mm Hg, P < 0.05). Positive and negative correlations were observed between β-stiffness index and PI (r = 0.39, P < 0.05), and between arterial compliance and PI (r = -0.59, P < 0.05), respectively.

CONCLUSIONS

The resistance-trained group showed higher central arterial stiffness and PI and lower arterial compliance. Central arterial stiffness and arterial compliance were associated with PI. Increased arterial stiffness and decreased arterial compliance with resistance training impair buffer function, resulting in increased CBF pulsatility.

CLINICAL TRIAL REGISTRATION

Trial Number UMIN000023816 URL: http://www.umin.ac.jp/icdr/index.html Official scientific title of the study: effect of increase arterial stiffness by resistance training on cerebral hemodynamic.

Effects of blood flow restricted exercise training on muscular strength and blood flow in older adults

BACKGROUND

In young adults, blood flow restricted exercise (BFRE) at relatively low intensities can increase muscle strength as effectively as conventional high intensity training. Ischemic exercise can also increase collateral blood flow in skeletal muscle. However, the effects of chronic BFRE on muscle strength and blood flow in older adults remain unknown. The purpose of this study was to compare the effects of 4weeks of BFRE training on skeletal muscle strength and blood flow between young and older subjects and between older adults performing BFRE and conventional high intensity resistance exercise.

METHODS

Maximum voluntary contraction (MVC), forearm girth, peak forearm blood flow (FBF) and forearm vascular conductance (FVC) were assessed before and after 4weeks of forearm resistance training with BFRE in older adults (O-BFRE, 63±1 y, n=9) and younger adults (Y-BFRE, 22±1 y, n=8) and with high intensity training at 75% maximum voluntary contraction in older adults (O-HI, 63±1 y, n=10).

RESULTS

MVC increased in all groups (O-BFRE, 33.4±4.7 to 36.3±4.7kg; Y-BFRE, 37.2±4.9 to 43.0±5.0kg; O-HI, 34.0±4.4 to 39.8±4.4kg; all p<0.05). Forearm girth increased in O-BFRE (26.3±1.1 to 26.7±1.1cm; p<0.05) and Y-BFRE (23.9±0.9 to 25.1±1.5cm; p<0.05) but not in O-HI (25.9±1.0 to 26.1±1.0cm; p=0.26). Peak forearm vascular conductance increased in Y-BFRE (0.190±0.016 to 0.311±0.031units; p=0.01) but not in O-BFRE (0.157±0.024 to 0.193±0.029units; p=0.48) and O-HI (0.188±0.035 to 0.227±0.035units; p=0.18).

CONCLUSION

These data suggest that chronic BFRE training is effective in increasing muscular strength, muscle size and vascularity in young adults but, in older adults, increases only muscular strength and size. Longer training durations or higher volumes may be required to evoke similar vascular adaptations in older adults.

Vascular compliance is reduced in vascular dementia and not in Alzheimer's disease

OBJECTIVE

to determine whether functional changes in the vasculature differ between Alzheimer's disease (AD) and vascular dementia (VAD).

DESIGN

we determined vascular stiffness in patients with a clinical and radiological diagnosis of either AD or VAD and compared them to normal age- and sex-matched controls.

METHODS

In all, 16 patients with late onset AD, 13 subjects with VAD and 16 age- and sex-matched controls were recruited to this study. Central arterial compliance (CAC), augmentation index (AI) and pulse wave velocity (PWV) (measures of arterial stiffness) were measured.

RESULTS

the mean age was 77.7 +/- 8.3 years (mean +/- SD) in the AD group, 79.7 +/- 8.9 years in the VAD group and 76.4 +/- 6.9 in the controls (P = 0.44). CAC was significantly lower in subjects with VAD compared to both the AD and the control groups (0.57 +/- 0.46 ml/mm Hg versus 1.12 +/- 0.57 and 1.1 +/- 0.47 ml/mm Hg respectively, P = 0.01). AI was significantly higher in the subjects with VAD compared to both the AD and the control groups (13.3 +/- 9.0 versus 3.5 +/- 11.4 and 4.2 +/- 9.7% respectively, P = 0.03). PWV in the muscular and elastic arteries were not statistically different between the three groups but tended to be highest in the VAD group for carotid-radial measurements.

CONCLUSIONS

the reduced CAC and increased AI in VAD subjects indicate that the disease process is associated with less vascular compliance of the large elastic arteries in these patients, but not in patients with AD.

Resistance training in men is associated with increased arterial stiffness and blood pressure but does not adversely affect endothelial function as measured by arterial reactivity to the cold pressor test

Resistance training is a popular mode of exercise, but may result in stiffening of the central arteries. Changes in carotid artery diameter were determined using the cold pressor test (CPT), which results in production of nitric oxide via sympathetic activation and is one of the novel methods available for assessing endothelial function in the carotid artery. To investigate the effect of resistance training on endothelial function, we designed a cross-sectional study of carotid arterial vasoreactivity to CPT in men participating in regular resistance training with increased carotid arterial stiffness compared with age-matched control subjects. Twelve resistance-trained middle-aged men (age 38.7 +/- 1.7 years) and 17 age-matched control subjects (age 36.8 +/- 1.2 years) were studied. The direction and magnitude of changes in carotid artery diameter were measured by B-mode ultrasonography during sympathetic stress induced by submersion of the foot in ice slush for 90 s. Carotid arterial beta-stiffness index, and systolic and mean arterial blood pressure were higher (7.7 +/- 0.7 versus 6.0 +/- 0.4 arbitrary units, 116 +/- 2 versus 131 +/- 4 mmHg and 86 +/- 2 versus 95 +/- 2 mmHg, respectively, all P < 0.05) in the resistance training group compared with control subjects. There were, however, no significant differences in the amount or percentage change in carotid artery diameter in CPT between the two groups (resistance training group, 0.33 +/- 0.07 mm and 5.2 +/- 1.1%; control group, 0.37 +/- 0.06 mm and 5.8 +/- 0.9%, respectively). These findings suggest that while carotid arterial stiffening and higher blood pressure are observed in regular resistance-trained men, these are not associated with abnormalities in carotid arterial vasoreactivity to sympathetic stimulus, which implies intact endothelial function.

Novel estrogen receptor alpha promoter polymorphism increases ventricular hypertrophic response to hypertension

Given the strong genetic contribution to blood pressure and left ventricular hypertrophy (LVH), and the influence of estrogen on these parameters, we hypothesized that polymorphisms in the estrogen receptor alpha (ERalpha) promoter may influence LVH. Three novel polymorphisms were identified upstream of the ERalpha alternatively spliced exon 1E, within sequence which demonstrated significant promoter activity in vitro. Demonstration of ERalpha E isoform expression in human ventricle by RT-PCR supported a possible functional role for the 1E novel polymorphisms in estrogen signaling in the heart. Indeed, G>A (-721 E) was significantly associated with LVH after controlling for systolic blood pressure and sex in a healthy population (n=74), contributing to 23% of interventricular septum (IVS) width variance (p<0.001) and 9.4% of left ventricular mass index (LVMI) variance (p=0.035). In a separate hypertensive cohort, male carriers of the A allele (n=8) had a 17% increase in IVS (95% CI: 6-28%) and a 19% increase in LVMI (3-34%) compared to GG homozygotes (n=84). We conclude that a novel polymorphism in the promoter of a cardiac mRNA splice isoform of ERalpha is associated with LVH.

Endothelial dysfunction and the kidney: emerging risk factors for renal insufficiency and cardiovascular outcomes in essential hypertension

Renal insufficiency in essential hypertension represents the expression of a medium- and small-size arteriolopathy characterized by intimal hyperplasia, hyalinosis, and smooth muscle cell hypertrophy (nephroangiosclerosis). Because in animal models endothelial dysfunction plays a role in this alteration, nephroangiosclerosis and the attendant renal insufficiency may be the expression of a systemic dysfunction of vascular endothelium. Endothelial function in the kidney vasculature of hypertensive individuals has been investigated little because studies on the hemodynamic response of the kidney to nitric oxide activation and blockade are laborious to perform. There is no direct proof that endothelial dysfunction in the forearm or in the coronary circulation is paralleled by a similar hemodynamic dysfunction in the kidney. A recent study in a large population of patients with essential hypertension showed that, independent of other risk factors, the GFR in these patients is strongly related to the forearm blood flow response to acetyl choline (an established test of endothelial function). Furthermore, in this study, C-reactive protein was inversely related to the GFR and with the vasodilatory response to acetyl choline, pointing to inflammation as a likely mechanism to explain the association between endothelial dysfunction and impaired renal function in essential hypertension. A dysfunctional endothelium may represent a critical link accounting for the risk for both renal impairment and cardiovascular complications in essential hypertension.

Age and regional specificity of peak limb vascular conductance in women

The influence of age on limb vasodilator capacity in women is unclear. The objectives of this study were to characterize and compare age-associated changes in forearm and calf peak vascular conductance (VC(peak); a functional index of arterial structure) in women and to identify physiological characteristics predictive of variation in limb-specific VC(peak). Peak conductance (plethysmographic flow/mean arterial pressure), VC(peak) of the forearm (forearm VC(peak)), and calf (calf VC(peak)) after 10 min of arterial occlusion were measured in 58 healthy, normally active women aged 21-79 yr. Aerobic capacity (cycle peak oxygen uptake), arterial health (pulse-wave velocity, ankle-brachial index), total cholesterol, limb-specific tissue composition (dual-energy X-ray absorptiometry), and isometric strength (handgrip, plantar flexion) were also assessed. The relative decline in calf VC(peak) with age (-6.8% per decade, P < 0.001) was greater than the forearm (-4.4% per decade, P = 0.004), in contrast to results previously reported for men (forearm decline > calf decline). Limb VC(peak) per kilogram muscle declined with age in the calf (-6.0% per decade; P = 0.002), but not the forearm (P = 0.12). Age, cholesterol, and regional tissue composition were significant predictors of peak conductance in both limbs; however, age was a stronger predictor of peak conductance in the calf. These results suggest that healthy aging is associated with a linear decline in limb vasodilator capacity in women, but the magnitude of this effect is region specific. Further research will be required to determine whether the decline in lower extremity vasodilator capacity with age explains diminished exercising leg vasodilation in older women.

Age and regional specificity of peak limb vascular conductance in men

Because of methodological variation in previous studies, age-associated changes in peak limb vascular conductance (VC(peak); a functional index of arterial structure) and its determinants remain poorly defined. The objectives of this study were to describe and compare age-associated changes in peak forearm and calf conductance across a broad age range and to identify physiological characteristics that are predictive of variation in limb-specific VC(peak). Peak conductance (plethysmographic flow/brachial mean arterial pressure) of the forearm (forearm VC(peak)) and calf (calf VC(peak)) after 10 min of arterial occlusion was measured twice in 68 healthy, normally active men aged 20-79 yr. Aerobic capacity (cycle peak oxygen consumption), arterial health (ankle-brachial index, pulse wave velocity), and limb-specific measures of muscle mass (dual-energy X-ray absorptiometry) and isometric strength (grip, plantar flexion) were also assessed. The relative decline in forearm VC(peak) with age (-6.6% per decade; P < 0.001) was greater than the decline in calf VC(peak) (-3.4% per decade; P = 0.004). Limb VC(peak) per kilogram of muscle declined with age in the forearm (-3.8% per decade; P = 0.004) but not in the calf (P = 0.35). Age, Vo(2 peak), and regional muscle mass were significant predictors of peak conductance in both limbs; however, these predictors explained considerably less variance in the calf than in the forearm. These results suggest that healthy aging is associated with a linear decline in limb vasodilator capacity in men, but the magnitude of this effect is reduced in the calf relative to the forearm. This could reflect regional differences in habitual muscle use with aging in normally active men.

Effects of multivitamins and low-dose folic acid supplements on flow-mediated vasodilation and plasma homocysteine levels in older adults

BACKGROUND

Hyperhomocysteinemia is associated with aging, endothelial dysfunction, and increased risk of coronary heart disease in older adults; however, the effects of homocysteine-lowering therapy on vascular reactivity in older persons are unknown. The objective of this study was to determine the effects of multivitamins (MV) and folic acid (FA) supplements on flow-mediated vasodilation (FMD) in older adults.

METHODS

Individuals > or =70 years old with homocysteine levels > or =10 micromol/L were recruited for this 40-week, prospective, single-blinded study. All subjects were treated sequentially, with each of the following daily therapies for 10 weeks: (1) placebo, (2) MV (400 microg FA, 6 mg vitamin B6, 25 microg vitamin B12), (3) placebo, then (4) MV + FA (total FA, 1400 microg). FMD, folate intake, and laboratory values were measured at each visit. Investigators were blinded to subject treatment phase when measuring vessel diameters and calculating FMD.

RESULTS

Twenty subjects (mean +/- SEM age, 78.0 +/- 1.2 [range, 70 to 88] years, 9 women) completed the MV and 17 completed the MV + FA interventions. FMD was impaired at baseline (2.0% +/- 1.2%). During the 40-week study, homocysteine levels decreased by 1.4 +/- 0.9 micromol/L (p(trend) = 0.034) from a baseline of 12.8 +/- 0.6 micromol/L; however, FMD did not change significantly (p(trend) = 0.874). FMD did not improve after therapy with MV alone (3.0% +/- 0.9% [week 10] vs 2.4% +/- 1.1% [week 20], P =.716) or with MV + FA (2.6% +/- 0.9% [week 30] vs 1.9% +/- 0.7% [week 40], P =.484).

CONCLUSIONS

At doses commonly prescribed in clinical practice, MV and FA supplements did not improve FMD in older adults with hyperhomocysteinemia.

Pharmacokinetics and Pharmacodynamics of Methylecgonidine, a Crack Cocaine Pyrolyzate

Methylecgonidine is formed from cocaine base when smoked and has been identified in biological fluids of crack smokers. Ecgonidine, a metabolite of methylecgonidine formed via esterase activity, also has been identified in similar samples collected from crack smokers. Methylecgonidine and ecgonidine can be used as biomarkers to differentiate smoking from cocaine use via other routes of administration. We determined the pharmacokinetic properties of methylecgonidine and ecgonidine in sheep after intravenous administration of methylecgonidine at doses of 3.0, 5.6, and 10.0 mg/kg using gas chromatography-mass spectrometric assays. Methylecgonidine clears quickly from blood with a half-life of 18 to 21 min, whereas ecgonidine has a longer half-life of 94 to 137 min. Because ecgonidine clears more slowly, it may be a more effective biomarker of cocaine smoking. The cardiovascular stimulant effects of cocaine contrast with reported in vitro muscarinic agonist effects of methylecgonidine, decreasing contractility and stimulating nitric oxide production in cardiac cells and tissues. To test the hypothesis that methylecgonidine produces cardiovascular effects in vivo consistent with muscarinic agonism, methylecgonidine was administered to sheep intravenously (0.1-3.0 mg/kg) while monitoring heart rate and blood pressure. Significant hypotension and tachycardia occurred in all three sheep. Two of the three sheep demonstrated mild bradycardia 3 to 5 min after methylecgonidine injection. Intravenous pretreatment with atropine methyl bromide (15 microg/kg) antagonized methylecgonidine-induced hypotension in all three sheep, supporting the hypothesis that methylecgonidine acts as a muscarinic agonist in vivo.

Age-dependent spontaneous coronary arterial thrombosis in transgenic mice that express a stable form of human plasminogen activator inhibitor-1

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) regulates fibrinolysis and has been reported to be an independent risk factor for ischemic cardiovascular events. This study describes the age-dependent development of spontaneous coronary arterial thrombi that are associated with evidence of subendocardial myocardial infarction in mice transgenic for human PAI-1.

METHODS AND RESULTS

We generated two independent transgenic mice founder lines that express a stable variant of active human PAI-1 under control of the murine preproendothelin-1 (mPPET-1) promoter. Backcrossed homozygous transgenic animals from founder line I had plasma PAI-1 levels of 23+/-12 ng/mL. PAI-1 transgenic animals younger than 4 months do not exhibit any evidence of arterial or venous thrombosis. Ninety percent of transgenic animals (n=10) older than 6 months developed spontaneous occlusions of typically multiple, penetrating coronary arteries, with histological evidence of subendocardial infarction identified in 50% of animals.

CONCLUSIONS

This study shows that chronically elevated levels of PAI-1 are associated with age-dependent coronary arterial thrombosis in mice transgenic for human PAI-1. This is the first study of a murine model of coronary thrombosis that occurs in the absence of severe hypercholesterolemia or multiple genetic manipulations. These findings provide new evidence to support the hypothesis that PAI-1 excess contributes to the development of coronary arterial thrombosis.

Peripheral endothelium-dependent flow-mediated vasodilatation is associated with left ventricular mass in older persons with hypertension

BACKGROUND

Increased left ventricular (LV) mass is associated with greater cardiovascular disease risk. Recent studies have also shown an association of increased LV mass with attenuated endothelium-dependent coronary flow reserve. Less is known about the association between LV mass and endothelium-dependent flow-mediated dilatation (FMD) in peripheral arteries, a noninvasive measure of endothelial function.

METHODS

Sixty-two subjects with untreated mild hypertension, aged 55 to 75 years and otherwise healthy, were examined. Resting blood pressure was obtained by the average of 4 to 5 visits, each at least 1 week apart. LV mass was determined from magnetic resonance imaging and was indexed by body surface area, height and height(2.7). Body composition was assessed with dual energy x-ray absorptiometry. FMD was measured as the percent change of brachial artery diameter during reactive hyperemia by use of high-resolution ultrasound.

RESULTS

Median LV mass index was 63 g/m2 (interquartile range, 58-73). In bivariate analysis, LV mass was correlated to lean body mass (r = 0.63, P <.001), diastolic blood pressure (r = 0.35, P <.01), and FMD (r = -0.27, P <.05). In multivariate analysis, 44% of the variance in log-LV mass was explained by lean body mass. An additional 6% of the variance was explained by FMD (P <.05). For each 1% point decrease in FMD, LV mass increased by 1.1%.

CONCLUSIONS

In addition to the expected influences of body size, impairment of brachial artery FMD was independently related to LV mass in elderly subjects with mild hypertension who did not yet have LV hypertrophy. Whether mild hypertension is the common mechanism linking LV mass and endothelial function has yet to be determined.

Tai Chi Chuan training is associated with enhanced endothelium-dependent dilation in skin vasculature of healthy older men

OBJECTIVES

The vascular endothelium modulates vascular tone by synthesizing and metabolizing vasoactive substances. Endothelium-dependent vasodilation declines with age. This study investigated whether Tai Chi Chuan (TCC) training could enhance endothelial function in the skin vasculature of older men.

SETTING

Community setting.

DESIGN

Basic hemodynamic characteristics and skin vascular response to endothelium-dependent and -independent vasodilators were studied.

PARTICIPANTS

Ten older men who practiced TCC, 10 older healthy sedentary men, and 12 younger healthy sedentary men. The older TCC subjects had practiced classical Yang TCC for a mean +/- standard deviation of 11.2 +/- 3.4 years; mean attendance was 5.1 +/- 1.8 times weekly. Sedentary subjects had not participated in any regular exercise training for at least 5 years.

MEASUREMENTS

Different doses of 1% acetylcholine (ACh) and 1% sodium nitroprusside (SNP) were iontophoretically applied to the skin of subjects' lower legs, and cutaneous microvascular perfusion responses were determined by laser doppler measurements. Additionally, arterial and venous hemodynamic variables were measured by impedance plethysmograph.

RESULTS

The older TCC group had higher lower leg arterial blood flow (LABF); LABF in response to reactive hyperemia; and lower leg venous capacity, tone and blood flow than their sedentary counterparts, but the older TCC group displayed similar arterial and venous hemodynamic variables to the younger sedentary group. The younger sedentary group had a higher ACh-induced cutaneous perfusion and a higher ratio of ACh- to SNP-induced cutaneous perfusion than the two older groups. The older TCC group showed a higher ACh-induced cutaneous perfusion and a higher ratio of ACh- to SNP-induced cutaneous perfusion than the older sedentary group. Skin vascular responses to SNP did not differ significantly between the three groups.

CONCLUSIONS

Regular practice of TCC is associated with enhanced endothelium-dependent dilation in skin vasculature of older individuals. Moreover, TCC training may delay the age-related decline of venous compliance and hyperemic arterial response.

A single nucleotide polymorphism in the promoter region of the human gene for osteoprotegerin is related to vascular morphology and function

Osteoprotegerin (OPG) is a secreted member of the tumor necrosis factor receptor family, and has previously been shown to regulate bone mass by inhibiting osteoclast differentiation and activation. Recent evidence indicates that OPG also plays a role in the vascular system, since ablation of the OPG gene in mice results in calcification of the aorta and renal arteries, and association has been found between serum levels of OPG and cardiovascular mortality. This study presents a novel single nucleotide polymorphism, a T/C transition located 129 bp upstream the TATA-box of the human OPG gene, detected by sequence analysis. The OPG genotype was determined by restriction fragment length polymorphism in a cohort consisting of 59 healthy subjects. The intima-media thickness (IMT) in the common carotid artery and maximal post-ischemic forearm blood flow (FBF) were investigated. Subjects with the CC genotype showed a significantly increased IMT (p<0.05) and a concommitantly reduced maximal FBF (p<0.01) as compared to those with the T allele. Thus, our results show that the polymorphism in the promoter region of OPG is associated with both vascular morphology and function in apparently healthy subjects.

Arterial stiffness is not improved in long-term use of estrogen

OBJECTIVE

The purpose of this study was to compare arterial stiffness in long-term users of estrogen who were postmenopausal, age-matched women who did not use estrogen, and women of fertile age.

STUDY DESIGN

In this clinical cross-sectional study, carotid, femoral, and aortic stiffness (estimated as elastic modulus and stiffness beta index) were assessed by ultrasonic phase-locked echo-tracking in 17 women who were postmenopausal and who were treated with 17 beta-estradiol implants (mean age, 68.8 years; mean duration of treatment, 20 years), 17 age-matched (+/-1 year) untreated women, and 20 women in the fertile age period.

RESULTS

Compared with women of fertile age, both postmenopausal groups had significantly higher stiffness elastic modulus and stiffness beta index (carotid, P <.001; femoral, P <.05; aorta, P <.001). However, for all 3 arteries, both stiffness indices were similar in estrogen users and nonusers and did not differ significantly. These results remained after an adjustment for systolic blood pressure, body mass index, and low-density lipoprotein cholesterol levels.

CONCLUSION

These data indicate that the arterial stiffening that is related to aging/menopause is not substantially affected by long-term estrogen therapy.

The effects of lipid-lowering and antioxidant vitamin therapies on flow-mediated vasodilation of the brachial artery in older adults with hypercholesterolemia

OBJECTIVES

The goal of this study was to determine the long-term effects of statins and antioxidant vitamins on flow-mediated vasodilation of the brachial artery in older adults with hypercholesterolemia.

BACKGROUND

Lipid-lowering therapy and antioxidant vitamins improve endothelium-dependent vasodilation in young and middle-aged adults with hypercholesterolemia, but their effects in older adults are not known.

METHODS

Two double-blind, placebo-controlled studies were performed in individuals > or =70 years old with low-density lipoprotein cholesterol (LDL-C) > or =140 mg/dl. In the first study, 37 subjects were randomized to receive (group 1) pravastatin for six months then pravastatin and vitamin E for six additional months or (group 2) vitamin E for six months, then pravastatin and vitamin E for six additional months. In the second study, additional 17 subjects sequentially received simvastatin for six months, then simvastatin and vitamins C and E for six additional months. Flow-mediated vasodilation of the brachial artery was measured by high-resolution ultrasound.

RESULTS

At baseline, subjects in both studies were similar in age (mean +/- SD, 75.8 +/- 4.2 years), gender, systolic blood pressure, total cholesterol (261.6 +/- 37.4 mg/dl), LDL-C (180.3 +/- 28.1 mg/dl), high-density lipoprotein cholesterol and triglycerides levels. Flow-mediated vasodilation was severely impaired (2.2 +/- 3.9%). Both statins reduced total and LDL-C levels (p < 0.001); however, neither statin, antioxidant vitamin regimen nor the combination of statins and antioxidant vitamins improved flow-mediated vasodilation of the brachial artery. At baseline, nitroglycerin-mediated vasodilation also was impaired (10.7 +/- 5.6%) and did not change in either study.

CONCLUSIONS

Older adults with hypercholesterolemia have impaired flow-mediated vasodilation of the brachial artery that does not improve after one year of therapy with statins and antioxidant vitamins, despite significant lipid-lowering.

Peripheral flow response to transient arterial forearm occlusion does not reflect myocardial perfusion reserve

BACKGROUND

Ultrasonographic evaluation of systemic arterial function is widely available, and a close relation of endothelial function in the coronary and brachial arteries has been documented. It is unknown, however, whether a similar correlation exists for their 2 microcirculatory territories and thus whether assessment of the systemic microcirculation can be used similarly as a surrogate marker of myocardial perfusion.

METHODS AND RESULTS

Twenty-three patients with documented coronary artery disease (CAD; 66+/-9 years old, 18 men), 16 patients with syndrome X (SX; 56+/-5 years old, 13 women), and 45 healthy control subjects (C; 34+/-9 years old, 22 men) were studied. Myocardial perfusion was measured at rest and after dipyridamole (0.56 mg. kg(-1). min(-1) over 4 minutes) by PET, and brachial artery blood flow was measured at rest and after transient forearm ischemia by standard Doppler ultrasound techniques. Dipyridamole increased myocardial perfusion in all groups (mL. g(-1). min(-1): CAD, 0.89+/-0.27 versus 1.62+/-0.67, P:<0.001; SX, 0.82+/-0.16 versus 1.67+/-0.49, P:<0.001; and C, 0.82+/-0.15 versus 2.32+/-0.64, P:<0.001). Postocclusion forearm flow increased similarly in all groups (CAD, 52+/-18 versus 174+/-77 mL/min, P:<0.001; SX, 49+/-29 versus 202+/-82 mL/min, P:<0.001; and C, 61+/-34 versus 229+/-108 mL/min, P:<0.001). No significant correlations were found between peripheral and myocardial microcirculatory beds for either resting flow, hyperemic flow, or flow reserve in any of the groups (r(2)<0.1, P:=NS).

CONCLUSIONS

The peripheral perfusion responses to transient forearm ischemia do not correlate with dipyridamole-induced myocardial hyperemia. The lack of correlation indicates different mechanisms of microvascular activation or regulation and confirms that extrapolations between findings in the 2 vascular beds are not suitable.

Blood flow rate in arteriovenous anastomoses: from the cradle to the grave

Blood flow rate was measured in the arteriovenous anastomoses (AVAs) in the cutaneous tissue of the pulp of the first toe in 15 children between 3 and 15 years old, and in the pulp of the thumb and the first toe in 16 adults between 27 and 93 years old (two subjects from each decade) by the heat-washout method. The examinations showed that AVA-blood flow rate decreased with increasing age, and the difference between children and adults was highly significant (P=0.001). Blood flow rate in the finger pulp was higher than in the toe pulp (P=0.025). No significant difference in blood flow rate was found in either thumb pulp or toe pulp between men and women.