Enhanced endothelial vasoreactivity in endurance-trained older men

Acute effects of MitoQ on vascular endothelial function are influenced by cardiorespiratory fitness and baseline FMD in middle-aged and older adults

A key mechanism promoting vascular endothelial dysfunction is mitochondrial-derived reactive oxygen species (mtROS). Aerobic exercise preserves endothelial function in preclinical models by lowering mtROS. However, the effects of mtROS on endothelial function in exercising and non-exercising adults is limited. In a double-blind, randomized, placebo-controlled crossover study design 23 (10 M/13 F, age 62.1 ± 11.5 years) middle-aged and older (MA/O, ≥45 years) adults were divided into two groups: exercisers (EX, n = 11) and non-exercisers (NEX, n = 12). All participants had endothelial function (brachial artery flow-mediated dilatation, FMDBA) measured before and ∼1 h after mitoquinone mesylate (MitoQ) (single dose, 80 mg) and placebo supplementation. A two-way repeated measures ANOVA was used to determine the effects of MitoQ and placebo on FMDBA. Pearson correlations assessed the association between the change in FMDBA with MitoQ and baseline FMDBA and cardiorespiratory fitness (CRF). Compared with placebo, MitoQ increased FMDBA in NEX by + 2.1% (MitoQ pre: 4.9 ± 0.4 vs. post: 7.0 ± 0.4 %, P = 0.004, interaction) but not in EX (P = 0.695, interaction). MitoQ also increased endothelial function in adults with a FMDBA <6% (P < 0.0001, interaction) but not >6% (P = 0.855, interaction). Baseline FMDBA and CRF were correlated (r = 0.44, P = 0.037), whereas the change in FMDBA with MitoQ was inversely correlated with CRF (r = -0.66, P < 0.001) and baseline FMDBA (r = -0.73, P < 0.0001). The relationship between the change in FMDBA and baseline FMDBA remained correlated after adjusting for CRF (r = -0.55, P = 0.007). These data demonstrate that MitoQ acutely improves FMDBA in NEX and EX adults who have a baseline FMDBA <6%. KEY POINTS: A key age-related change contributing to increased cardiovascular disease (CVD) risk is vascular endothelial dysfunction due to increased mitochondrial-derived reactive oxygen species (mtROS). Aerobic exercise preserves endothelial function via suppression of mtROS in preclinical models but the evidence in humans is limited. In the present study, a single dose of the mitochondria-targeted antioxidant, mitoquinone mesylate (MitoQ), increases endothelial function in non-exercisers with lower cardiorespiratory fitness (CRF) but not in exercisers with higher CRF. The acute effects of MitoQ on endothelial function in middle-aged and older adults (MA/O) are influenced by baseline endothelial function independent of CRF. These data provide initial evidence that the acute MitoQ-enhancing effects on endothelial function in MA/O adults are influenced, in part, via CRF and baseline endothelial function.

The impact of the 24-h movement spectrum on vascular remodeling in older men and women: a review

Aging is associated with increased risk of cardiovascular and cerebrovascular events, which are preceded by early, negative remodeling of the vasculature. Low physical activity is a well-established risk factor associated with the incidence and development of disease. However, recent physical activity literature indicates the importance of considering the 24-h movement spectrum. Therefore, the purpose of this review was to examine the impact of the 24-h movement spectrum, specifically physical activity (aerobic and resistance training), sedentary behavior, and sleep, on cardiovascular and cerebrovascular outcomes in older adults, with a focus on recent evidence (<10 yr) and sex-based considerations. The review identifies that both aerobic training and being physically active (compared with sedentary) are associated with improvements in endothelial function, arterial stiffness, and cerebrovascular function. Additionally, there is evidence of sex-based differences in endothelial function: a blunted improvement in aerobic training in postmenopausal women compared with men. While minimal research has been conducted in older adults, resistance training does not appear to influence arterial stiffness. Poor sleep quantity or quality are associated with both impaired endothelial function and increased arterial stiffness. Finally, the review highlights mechanistic pathways involved in the regulation of vascular and cerebrovascular function, specifically the balance between pro- and antiatherogenic factors, which mediate the relationship between the 24-h movement spectrum and vascular outcomes. Finally, this review proposes future research directions: examining the role of duration and intensity of training, combining aerobic and resistance training, and exploration of sex-based differences in cardiovascular and cerebrovascular outcomes.

Routine Assessment and Promotion of Physical Activity in Healthcare Settings: A Scientific Statement From the American Heart Association

Physical inactivity is one of the most prevalent major health risk factors, with 8 in 10 US adults not meeting aerobic and muscle-strengthening guidelines, and is associated with a high burden of cardiovascular disease. Improving and maintaining recommended levels of physical activity leads to reductions in metabolic, hemodynamic, functional, body composition, and epigenetic risk factors for noncommunicable chronic diseases. Physical activity also has a significant role, in many cases comparable or superior to drug interventions, in the prevention and management of >40 conditions such as diabetes mellitus, cancer, cardiovascular disease, obesity, depression, Alzheimer disease, and arthritis. Whereas most of the modifiable cardiovascular disease risk factors included in the American Heart Association’s My Life Check - Life’s Simple 7 are evaluated routinely in clinical practice (glucose and lipid profiles, blood pressure, obesity, and smoking), physical activity is typically not assessed. The purpose of this statement is to provide a comprehensive review of the evidence on the feasibility, validity, and effectiveness of assessing and promoting physical activity in healthcare settings for adult patients. It also adds concrete recommendations for healthcare systems, clinical and community care providers, fitness professionals, the technology industry, and other stakeholders in order to catalyze increased adoption of physical activity assessment and promotion in healthcare settings and to contribute to meeting the American Heart Association’s 2020 Impact Goals.

Homeostatic effect of laughter on diabetic cardiovascular complications: The myth turned to fact

AIMS

Laughter has been used for centuries to alleviate pain in morbid conditions. It was not until 1976 that scientists thought about laughter as a form of therapy that can modulate hormonal and immunological parameters that affect the outcome of many serious diseases. Moreover, laughter therapy was shown to be beneficial in type 2 diabetes mellitus (T2DM) by delaying the onset of many diabetic complications. Laughter is also described to influence the cardiovascular and endothelial functions and thus may protect against diabetic cardiovascular complications. In this review, we outline the different biochemical, physiological and immunological mechanisms by which laughter may influence the overall state of wellbeing and enhance disease prognosis. We also focus on the biological link between laughter therapy and diabetic cardiovascular complications as well as the underlying mechanisms involved in T2DM.

METHODS

Reviewing all the essential databases for "laughter" and "type 2 diabetes mellitus".

RESULTS

Although laughter therapy is still poorly investigated, recent studies show that laughter may retard the onset of diabetic complications, enhance cardiovascular functions and rectify homeostatic abnormalities associated with T2DM.

CONCLUSIONS

Laughter therapy is effective in delaying diabetic complications and should be used as an adjuvant therapy.

Microvascular Dilator Function in Athletes: A Systematic Review and Meta-analysis

PURPOSE

Despite the growing research interest in vascular adaptations to exercise training over the last few decades, it remains unclear whether microvascular function in healthy subjects can be further improved by regular training. Herein, we sought to systematically review the literature and determine whether microvascular dilator function is greater in athletes compared to age-matched healthy untrained subjects.

METHODS

We conducted a systematic search of MEDLINE, Cochrane, EMBASE, and Web of Science since their inceptions until October 2013 for articles evaluating indices of primarily microvascular endothelium-dependent or endothelium-independent dilation (MVEDD and MVEID, respectively) in athletes. A meta-analysis was performed to determine the standardized mean difference (SMD) in MVEDD and MVEID between athletes and age-matched controls. Subgroup analyses were used to study potential moderating factors.

RESULTS

Thirty-six studies were selected after systematic review, comprising 521 athletes (506 endurance-trained and 15 endurance- and strength-trained) and 496 age-matched control subjects. After data pooling, athletes presented higher MVEDD (31 studies; SMD, 0.47; P < 0.00001) and MVEID (14 studies; SMD, 0.51; P < 0.00001) compared with the control subjects. Similar results were observed in young (younger than 40 yr) and master (older than 55 yr) athletes when analyzed separately.

CONCLUSION

Both young and master athletes present enhanced microvascular function compared with age-matched untrained but otherwise healthy subjects. These data provide evidence of a positive association between exercise training and microvascular function in the absence of known underlying cardiovascular disease.

Age related vascular endothelial function following lifelong sedentariness: positive impact of cardiovascular conditioning without further improvement following low frequency high intensity interval training

Aging is associated with diffuse impairments in vascular endothelial function and traditional aerobic exercise is known to ameliorate these changes. High intensity interval training (HIIT) is effective at improving vascular function in aging men with existing disease, but its effectiveness remains to be demonstrated in otherwise healthy sedentary aging. However, the frequency of commonly used HIIT protocols may be poorly tolerated in older cohorts. Therefore, the present study investigated the effectiveness of lower frequency HIIT (L_fHIIT) on vascular function in a cohort of lifelong sedentary (SED; n =22, age 62.7 ± 5.2 years) men compared with a positive control group of lifelong exercisers (LEX; n = 17, age 61.1 ± 5.4 years). The study consisted of three assessment phases; enrolment to the study (Phase A), following 6 weeks of conditioning exercise in SED (Phase B) and following 6 weeks of low frequency HIIT in both SED and LEX (L_fHIIT; Phase C). Conditioning exercise improved FMD in SED (3.4 ± 1.5% to 4.9 ± 1.1%; P <0.01) such that the difference between groups on enrolment (3.4 ± 1.5% vs. 5.3 ± 1.4%; P <0.01) was abrogated. This was maintained but not further improved following L_fHIIT in SED whilst FMD remained unaffected by L_fHIIT in LEX. In conclusion, L_fHIIT is effective at maintaining improvements in vascular function achieved during conditioning exercise in SED. L_fHIIT is a well‐tolerated and effective exercise mode for reducing cardiovascular risk and maintaining but does not improve vascular function beyond that achieved by conditioning exercise in aging men, irrespective of fitness level.

The effects of low frequency high intensity interval training (HIIT) on vascular endothelial function in lifelong sedentary men remains currently unknown. The present study examined the impact of low frequency HIIT following conditioning exercise on low determinants of vascular endothelial function and angiogenic biomarkers in aging men compared with a positive control group of similarly aged. The major findings of this study indicate that low frequency HIIT is a well‐tolerated and effective exercise mode for reducing cardiovascular risk and maintaining but not improving endothelial function beyond that achieved by conditioning exercise in aging men, irrespective of fitness level.

The association of cardiorespiratory fitness with endothelial or smooth muscle vasodilator function

BACKGROUND

Maximal oxygen consumption (VO2max) is strongly associated with peripheral vasodilator function as determined by exercise-induced vasodilation. However, findings with regard to its relation with non-exercise-stimulated vasodilation are unclear. The purpose of this study was to systematically review published literature reporting associations between VO2max and endothelial function (EF) or smooth muscle function (SMF).

DESIGN AND METHODS

We conducted a systematic search of MEDLINE, Cochrane and Web of Science, since their inceptions until April 2014 for articles reporting the association between (a) VO2max during incremental exercise and (b) endothelium-dependent or -independent vasodilator function, by means of correlation and/or regression analysis.

RESULTS

Fifty-six articles exploring 88 associations between VO2max and vascular EF or SMF were included, involving a total of 4159 healthy and diseased subjects. VO2max was determined by incremental cycle ergometer (64%), treadmill (33%) and cycle ergometer/treadmill (3%) exercise. Vasodilator function variables were assessed in the upper limb (86%), lower limb (10%) and both upper and lower limbs (3%). Most of the evaluated bivariate associations involved EF stimuli such as flow-mediated dilation (FMD) (n = 29) or blood flow occlusion (BFO) (n = 18). VO2max was significantly associated with FMD and BFO in 59% and 67% of bivariate associations and 46% and 33% of age-independent associations, respectively. Explored bivariate associations regarding SMF involved sodium nitroprusside (SNP) iontophoresis (n = 7) and nitrate-mediated dilation (NMD) (n = 4). VO2max was associated with NMD in 50% of bivariate associations and 50% of age-independent associations. VO2max was not associated with SNP iontophoresis. Results were similar for associations including only healthy subjects.

CONCLUSIONS

The association between VO2max and EF or SMF is moderately frequent and independent of health status, despite very few studies having assessed vasodilator function in the lower limb.

Prevention of age-related endothelial dysfunction by habitual aerobic exercise in healthy humans: possible role of nuclear factor κB

Habitual aerobic exercise prevents age-related impairments in endothelium-dependent dilation (EDD). We have hypothesized that the pro-inflammatory transcription factor nuclear factor κB (NF-κB) impairs EDD with sedentary aging, and habitual aerobic exercise prevents this age-related suppression of EDD by NF-κB. To test this hypothesis, we have inhibited NF-κB signalling via oral salsalate administration in healthy older aerobic exercise-trained adults (OT, n=14, 58 ± 2 years), older non-exercising adults (ON, n=16, 61 ± 1 years) and young non-exercising controls (YN, n=8, 23 ± 1 years). Salsalate reduced endothelial cell expression of NF-κB p65 by ~25% in ON (P<0.05) but did not significantly change expression in OT or YN (P>0.05). EDD, assessed by brachial artery flow-mediated dilation (FMD), was improved by salsalate in ON (4.0 ± 0.7% compared with 6.8 ± 0.7%, placebo compared with salsalate, P<0.001) but did not change with salsalate in OT or YN (OT: 7.2 ± 0.7% compared with 7.7 ± 0.6%; YN: 7.6 ± 0.9% compared with 8.1 ± 0.8%; placebo compared with salsalate, P>0.05). Endothelium-independent dilation was not affected by salsalate in any group (P>0.05). In ON, vitamin C infusion improved FMD by ~30% during placebo (P<0.001) but had no affect during salsalate (P>0.05). In OT and YN, vitamin C infusion did not affect FMD during either placebo or salsalate (P>0.05). Salsalate reduced endothelial cell nitrotyrosine content by ~25% and NADPH oxidase p47phox expression by ~30% in ON (P<0.05) but had no effect in OT or YN (P>0.05). Our results suggest that endothelial NF-κB signalling is associated with oxidative stress-related impairment of EDD in healthy non-exercising but not aerobically exercising older adults. This may be a key mechanism by which regular aerobic exercise preserves endothelial function and reduces cardiovascular risk with aging.

Edward F. Adolph Distinguished Lecture: The remarkable anti-aging effects of aerobic exercise on systemic arteries

Cardiovascular diseases (CVD) remain the leading cause of morbidity and mortality in modern societies, and advancing age is the major risk factor for CVD. Arterial dysfunction, characterized by large elastic artery stiffening and endothelial dysfunction, is the key event leading to age-associated CVD. Our work shows that regular aerobic exercise inhibits large elastic artery stiffening with aging (optimizes arterial compliance) and preserves endothelial function. Importantly, among previously sedentary late middle-aged and older adults, aerobic exercise improves arterial stiffness and enhances endothelial function in most groups and, therefore, also can be considered a treatment for age-associated arterial dysfunction. The mechanisms by which regular aerobic exercise destiffens large elastic arteries are incompletely understood, but existing evidence suggests that reductions in oxidative stress associated with decreases in both adventitial collagen (fibrosis) and advanced glycation end-products (structural protein cross-linking molecules), play a key role. Aerobic exercise preserves endothelial function with aging by maintaining nitric oxide bioavailability via suppression of excessive superoxide-associated oxidative stress, and by inhibiting the development of chronic low-grade vascular inflammation. Recent work from our laboratory supports the novel hypothesis that aerobic exercise may exert these beneficial effects by directly inducing protection to aging arteries against multiple adverse factors to which they are chronically exposed. Regular aerobic exercise should be viewed as a "first line" strategy for prevention and treatment of arterial aging and a vital component of a contemporary public health approach for reducing the projected increase in population CVD burden.

Vascular Aging across the Menopause Transition in Healthy Women

Vascular aging, featuring endothelial dysfunction and large artery stiffening, is a major risk factor for developing cardiovascular disease (CVD). In women, vascular aging appears to be accelerated during the menopause transition, particularly around the late perimenopausal period, presumably related to declines in ovarian function and estrogen levels. The mechanisms underlying endothelial dysfunction and large artery stiffening with the menopause transition are not completely understood. Oxidative stress and the proinflammatory cytokine tumor necrosis factor-α contribute to endothelial dysfunction and large artery stiffening in estrogen-deficient postmenopausal women. Habitual endurance exercise attenuates the age-related increase in large artery stiffness in estrogen-deficient postmenopausal women and can reverse arterial stiffening to premenopausal levels in estrogen-replete postmenopausal women. In contrast, estrogen status appears to play a key permissive role in the adaptive response of the endothelium to habitual endurance exercise in that endothelial improvements are absent in estrogen-deficient women but present in estrogen-replete women. We review here the current state of knowledge on the biological defects underlying vascular aging across the menopause transition, with particular focus on potential mechanisms, the role of habitual exercise in preserving vascular health, and key areas for future research.

Predictors of improvement in endothelial function after exercise training in a diverse sample of postmenopausal women

BACKGROUND

Endothelial dysfunction measured via flow-mediated dilation (FMD) is associated with greater risk of future hypertension and cardiovascular events in postmenopausal women. Aerobic exercise training has been shown to improve endothelial function in Caucasian populations, but has not been evaluated specifically in African Americans. This has clinical importance due to the increased prevalence of cardiovascular disease in African Americans.

METHODS

In the present pilot study, 8 African American (age: 55.8±1.7 years, peak oxygen uptake [VO2 peak]: 21.0±3.9 mL/kg/minute, body mass index [BMI]: 30.1± 6.3 kg/m(2)) and 16 Caucasian (age: 57.2±5.9 years, VO2 peak: 21.8±3.7 mL/kg/minute, BMI: 29.3±5.2 kg/m(2)) sedentary postmenopausal women underwent brachial artery FMD measurements before and after 12 weeks of aerobic exercise training. FMD was quantified by comparing B-mode ultrasound images of the brachial artery at rest and following reactive hyperemia after 5 minutes of forearm occlusion. Participants performed aerobic exercise training 4 days per week for 12 weeks.

RESULTS

Despite improvements in fitness in both groups, aerobic exercise training did not significantly improve FMD in African American (5.8% to 5.7%, p=0.950) or Caucasian postmenopausal women (5.7% to 6.6%, p=0.267). In women with the greatest impairment in endothelial function at baseline (FMD<4.5%), a significant improvement in FMD was observed, independent of race, following exercise training (2.2% to 6.2%, p=0.007).

CONCLUSION

The benefits of aerobic exercise training on endothelial function in postmenopausal women are most pronounced in women with endothelial dysfunction prior to training and do not appear to be affected by race.

Effects of aging and exercise training on skeletal muscle blood flow and resistance artery morphology

With old age, blood flow to the high-oxidative red skeletal muscle is reduced and blood flow to the low-oxidative white muscle is elevated during exercise. Changes in the number of feed arteries perforating the muscle are thought to contribute to this altered hyperemic response during exercise. We tested the hypothesis that exercise training would ameliorate age-related differences in blood flow during exercise and feed artery structure in skeletal muscle. Young (6-7 mo old, n = 36) and old (24 mo old, n = 25) male Fischer 344 rats were divided into young sedentary (Sed), old Sed, young exercise-trained (ET), and old ET groups, where training consisted of 10-12 wk of treadmill exercise. In Sed and ET rats, blood flow to the red and white portions of the gastrocnemius muscle (Gast(Red) and Gast(White)) and the number and luminal cross-sectional area (CSA) of all feed arteries perforating the muscle were measured at rest and during exercise. In the old ET group, blood flow was greater to Gast(Red) (264 ± 13 and 195 ± 9 ml · min(-1) · 100 g(-1) in old ET and old Sed, respectively) and lower to Gast(White) (78 ± 5 and 120 ± 6 ml · min(-1) · 100 g(-1) in old ET and old Sed, respectively) than in the old Sed group. There was no difference in the number of feed arteries between the old ET and old Sed group, although the CSA of feed arteries from old ET rats was larger. In young ET rats, there was an increase in the number of feed arteries perforating the muscle. Exercise training mitigated old age-associated differences in blood flow during exercise within gastrocnemius muscle. However, training-induced adaptations in resistance artery morphology differed between young (increase in feed artery number) and old (increase in artery CSA) animals. The altered blood flow pattern induced by exercise training with old age would improve the local matching of O(2) delivery to consumption within the skeletal muscle.

Central arterial aging and the epidemic of systolic hypertension and atherosclerosis

The structure and function of central arteries change throughout the lifetime of humans and animals. Since atherosclerosis and hypertension are prevalent in epidemic proportion among older persons, it is reasonable to hypothesize that specific mechanisms that underlie the arterial substrate that has been altered by an "aging process" are intimately linked to arterial diseases. Indeed, recent studies reveal a profile of arterial cell and matrix properties that emerges with advancing age within the grossly normal appearing aortic wall of both animals and humans. This profile is proinflammatory, and is manifested by intimal infiltration of fetal cells, increased production of angiotensin II (Ang II)-signaling pathway molecules, eg, matrix metalloproteases (MMPs), and monocyte chemoattractant protein (MCP-1), transforming growth factor B1 (TGF-beta1), enhanced activation of MMPs, TGF-beta, and NADPH oxidase, and reduced nitric oxide (NO) bioavailability. This profile is similar to that induced at younger ages in experimental animal models of hypertension or atherosclerosis. In humans, this proinflammatory state, which occurs in the absence of lipid deposition, appears to be attributable to aging, per se. Other well known human risk factors, eg, altered lipid metabolism, smoking, and lack of exercise, interact with this arterial substrate that is altered by aging and render the aging human artery fertile soil for facilitation of the initiation and progression of arterial diseases. Therapies to reduce or retard this age-associated proinflammatory state within the grossly appearing arterial wall central arteries, in addition to slowing arterial aging, per se, may have a substantial impact on the quintessential age-associated arterial diseases of our society.

The Relationship between Multiple Health Behaviours and Brachial Artery Reactivity

Background. The effects of smoking, alcohol consumption, obesity, and a sedentary lifestyle on endothelial function (EF) have only been examined separately. The relative contributions of these behaviours on EF have therefore not been compared. Purpose. To compare the relative associations between these four risk factors and brachial artery reactivity in the same sample. Methods. 328 patients referred for single-photon emission computed tomography (SPECT) exercise stress tests completed a nuclear-medicine-based forearm hyperaemic reactivity test. Self-reported exercise behaviour, smoking habits, and alcohol consumption were collected and waist circumference was measured. Results. Adjusting for relevant covariates, logistic regression analyses revealed that waist circumference, abstinence from alcohol, and past smoking significantly predicted poor brachial artery reactivity while physical activity did not. Only waist circumference predicted continuous variations in EF. Conclusions. Central adiposity, alcohol consumption, and smoking habits but not physical activity are each independent predictors of poor brachial artery reactivity in patients with or at high risk for cardiovascular disease.

Endothelial function after 10 days of bed rest in individuals at risk for type 2 diabetes and cardiovascular disease

Physical inactivity is considered to be deleterious to vascular health, and in particular in first-degree relatives to patients with type 2 diabetes (FDR) and persons born with low birth weight (LBW), who may later in life develop cardiovascular disease. A period of imposed physical inactivity could unmask this risk. We hypothesized that the impact of physical inactivity on endothelial function would be more marked in subjects at increased risk for type 2 diabetes and cardiovascular disease (LBW and FDR) compared with a matched control group (CON), all of whom were recruited via advertisements and via the Danish Birth Registry. Twenty LBW, 20 CON and 13 FDR were studied before and after 10 days of bed rest. Forearm blood flow (FBF) was measured by venous occlusion plethysmography during brachial intra-arterial infusion of acetylcholine or adenosine at baseline and with superimposed hyperinsulinaemia. Markers of endothelial activation and inflammation were measured in plasma. Bed rest did not change the vasodilator responses to adenosine or acetylcholine alone in any group, but reduced vasodilator responses to adenosine or acetylcholine during hyperinsulinaemia in LBW. Bed rest impaired insulin-mediated vasodilatation in CON and LBW and increased endothelial activation markers in FDR and LBW but not in CON. Vasodilator responses were very low in FDR prior to bed rest, and did not decrease further during bed rest. Physical inactivity does not impair endothelium-dependent vasodilatation per se, but the vascular vasodilator effect of insulin diminished in CON and LBW after bed rest. In FDR, a further deterioration of FBF with inactivity is not possible.

Peripheral endothelial dysfunction is associated with gas exchange inefficiency in smokers

Aims

To assess the cross-sectional association between exercise capacity, gas exchange efficiency and endothelial function, as measured by flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD) of the brachial artery, in a large-scale population-based survey.

Methods

The study population was comprised of 1416 volunteers 25 to 85 years old. Oxygen uptake at anaerobic threshold (VO₂@AT), peak exercise (peakVO₂) and ventilatory efficiency (VE vs. VCO₂ slope and VE/VCO₂@AT) were assessed on a breath-by-breath basis during incremental symptom-limited cardiopulmonary exercise. FMD and NMD measurements at rest were performed using standardised ultrasound techniques.

Results

Multivariable logistic regression analyses revealed a significant association between FMD and ventilatory efficiency in current smokers but not in ex-smokers or non-smokers. There was no association between FMD and VO₂@AT or peak VO₂. In current smokers, for each one millimetre decrement in FMD, VE/VCO₂@AT improved by -3.6 (95% CI -6.8, -0.4) in the overall population [VE vs. VCO₂ slope -3.9 (-7.1, -0.6)]. These results remained robust after adjusting for all major influencing factors. Neither exercise capacity nor ventilatory efficiency was significantly associated with NMD.

Conclusion

In current smokers, FMD is significantly associated with ventilatory efficiency. This result may be interpreted as a potential clinical link between smoking and early pulmonary vasculopathy due to smoking.

The ageing cardiovascular system

The increase in the ageing population has generated much interest and research into what constitutes normal ageing. By identifying normal ageing processes it is hoped it will be possible to distinguish risk factors for the development of abnormal or premature ageing.

This review discusses biological, structural and mechanical changes in the cardiovascular system with ageing that are thought to increase the risk of cardiovascular disease with ageing. Contributory factors are thought to be genetic and lifestyle related. Measurements of biological as opposed to chronological ageing such as vascular stiffness are explored as a possible useful predictor of cardiovascular morbidity and mortality, indicating its possible utilization as a non-invasive screening tool in older people.

The identification of those at risk of cardiovascular disease and modification of risk factors may minimize interactions of the ageing process and therefore reduce the incidence of cardiovascular disease within the UK population.

Sex-specific effects of habitual aerobic exercise on brachial artery flow-mediated dilation in middle-aged and older adults

Brachial artery FMD (flow-mediated dilation) is impaired with aging and is associated with an increased risk of CVD (cardiovascular disease). In the present study, we determined whether regular aerobic exercise improves brachial artery FMD in MA/O (middle-aged/older) men and post-menopausal women. In sedentary MA/O adults (age, 55-79 years) without CVD, 8 weeks of brisk walking (6 days/week for approx. 50 min/day; randomized controlled design) increased treadmill time approx. 20% in both MA/O men (n=11) and post-menopausal women (n=15) (P<0.01), without altering body composition or circulating CVD risk factors. Brachial artery FMD increased >50% in the MA/O men (from 4.6±0.6 to 7.1±0.6%; P<0.01), but did not change in the post-menopausal women (5.1±0.8 compared with 5.4±0.7%; P=0.50). No changes occurred in the non-exercising controls. In a separate cross-sectional study (n=167), brachial artery FMD was approx. 50% greater in endurance-exercise-trained (6.4±0.4%; n=45) compared with sedentary (4.3±0.3%; n=60) MA/O men (P<0.001), whereas there were no differences between endurance-trained (5.3±0.7%, n=20) and sedentary (5.6±0.5%, n=42) post-menopausal women (P=0.70). Brachial artery lumen diameter, peak hyperaemic shear rate and endothelium-independent dilation did not differ with exercise intervention or in the endurance exercise compared with sedentary groups. In conclusion, regular aerobic exercise is consistently associated with enhanced brachial artery FMD in MA/O men, but not in post-menopausal women. Some post-menopausal women without CVD may be less responsive to habitual aerobic exercise than MA/O men.

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.

The association between flow-mediated dilation and physical function in older men

The probability that an individual is able to live independently decreases sharply below the threshold score of 57 units on the physical functional performance (PFP-10) test.

PURPOSE

To examine the relation between brachial artery flow-mediated dilation (BAFMD) on individual and total scores on the PFP-10. We hypothesized that lower scores on the PFP-10 test would be associated with lower BAFMD.

METHODS

Sixty-four men (age, 84 +/- 11 yr) from the Louisiana Healthy Aging Study were studied. Participants were classified by their performance on the PFP-10 test (Class I, score <26; Class II, score between 26 and 57; and Class III, score > 57). BAFMD was assessed after 5 min of forearm occlusion, using high-resolution ultrasonography.

RESULTS

The average total score on the PFP-10 test and BAFMD were 42.9 +/- 22 U and 2.76 +/- 2.13%, respectively. The BAFMD was associated with total PFP-10 score (r = 0.45, P = 0.0001) and age (r = -0.36, P = 0.003). BAFMD was significantly different (P = 0.001) between the PFP-10 classes (Class I, 1.44% [95% CI, 0.49-2.39]; Class II, 2.67% [95% CI, 1.95-3.38]; and Class III, 4.01% [95% CI, 3.16-4.85]).

CONCLUSIONS

This study reports significant relationships between BAFMD and individual and combined measures of physical function in elderly men. More specifically, when individuals were categorized based on their PFP-10 total score, those in the highest functional class, exhibited the highest BAFMD, compared to those in the middle class, who had greater vasoreactivity than those in the lowest functional class.

Hand exercise test for the assessment of endothelium-dependent vasodilatation in subjects with type 1 diabetes

BACKGROUND

At present, endothelial dysfunction is best assessed in vivo with measurement of flow-mediated dilatation (FMD) with Doppler ultrasound scanning. This test, however, does not account for the subject's age and is uncomfortable for patients. The aim of the study was to compare a new test for endothelium function assessment using hand exercise load.

METHODS

The study group comprised 31 male patients with type 1 diabetes and 72 healthy men as controls. The subjects in both groups were subdivided into three age groups: 18-30 (subgroup A), 31-45 (subgroup B), and 46-60 (subgroup C) years. FMD of the brachial artery with induction of hand ischemia was conducted in all the subjects. Afterwards, an originally designed test using standardized hand exercise with the use of a training device was performed.

RESULTS

In the youngest group of type 1 diabetes patients the effect of hand ischemia on brachial artery diameter was greater than in the two older age subgroups: baseline artery diameter increased by 0.23 +/- 0.11 mm (5.7%), 0.19 +/- 0.09 mm (4.3%), and 0.13 +/- 0.02 mm (2.8%), respectively (P < 0.01). In the hand exercise test, artery diameter increased in the youngest subjects by 0.39 +/- 0.11 mm (9.5%) and in the two older groups by 0.26 +/- 0.07 mm (5.6%) and 0.18 +/- 0.09 mm (4.5%) (P < 0.05), respectively. In subgroups A, B and C, vasodilation after hand exercise test was greater by 67%, 30%, and 32% (P < 0.01), respectively, compared with the effect of the ischemic test. In the controls similar effects and relationship between ischemic and hand exercise tests were noted, however, with a smaller difference between the two tests.

CONCLUSIONS

The hand exercise test results in a greater difference in vessel diameter before and after the test stimulus, which might substantially improve its feasibility. The hand exercise test could be a useful alternative tool for endothelial function assessment, especially in type 1 diabetes subjects.

Additive beneficial effects of lactotripeptides intake with regular exercise on endothelium-dependent dilatation in postmenopausal women

BACKGROUND

Peripheral conduit artery endothelium-dependent dilatation decreases with aging in humans. Lactotripeptides (LTPs) and regular exercise can improve endothelium-dependent dilatation, but combining these lifestyle modifications may be more effective than either treatment alone. We conducted a randomized, place-controlled trial with four different intervention arms.

METHODS

A total of 43 postmenopausal women (50-65 years old) were randomly divided into placebo, LTP, exercise and placebo (Ex+placebo), or exercise and LTP (Ex+LTP) groups. LTP or placebo was administered orally for 8 weeks. The exercise groups completed an 8-week moderate aerobic exercise (walking or cycling) intervention.

RESULTS

There were no statistically significant differences in baseline flow-mediated dilatation (FMD) and most other key dependent variables among the groups. FMD significantly increased in the LTP, Ex+placebo, and Ex+LTP groups whereas no such changes were observed in the placebo control group. The magnitude of increases in FMD was significantly greater in the Ex+LTP group than other intervention groups.

CONCLUSION

We concluded that LTP ingestion combined with regular aerobic exercise improves endothelium-dependent dilatation to a greater extent than monotherapy with either intervention alone in postmenopausal women.

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.

The effect of mirthful laughter on the human cardiovascular system

It has become increasingly recognized and more widely acknowledged during the past several decades, that a complex relationship exists between behavior associated with emotion and the human cardiovascular (CV) system. Early studies focused on the interplay between negative emotions and elevated CV risk, an effect that has in large part been attributed to increased adrenergic activity. Thus, a variety of adverse CV effects ranging from sudden cardiac death triggered by natural disasters such as earthquakes to transient myocardial stunning resulting from heightened sympathetic overload have been identified in response to acute emotional distress. In fact, the biologic interplay between emotion and CV health has been greatly enhanced through studies of the vascular endothelium. As the largest organ in humans, the inner blood vessel lining serves as a conduit for the transfer of blood cells, lipids and various nutrients across the lumen to neighboring tissues. Healthy endothelial cells secrete vasoactive chemicals, most notably endothelial-derived relaxing factor or nitric oxide (NO), that effects smooth muscle relaxation and vessel dilation via a cyclic guanosine monophosphate (cGMP) dependent protein kinase signaling pathway. In addition, endothelial derived NO may reduce vascular inflammation by attenuating or inhibiting leukocyte adhesion and subendothelial transmigration as well as decreasing platelet activation via cGMP mediated pathways. Taken together, studying the endothelium provides an exceptional opportunity to advance our understanding of the potentially important interrelationship between emotions and the vasculature. Premised on the identification of physiological and biochemical correlates, the former was demonstrated after intracoronary administration of acetylcholine yielded paradoxical endothelial vasoconstriction in response to mental stress exercises. More recently, the brachial artery reactivity test (BART) has permitted endothelial function to be assessed in a non-invasive manner. In addition to traditional CV risk factors, exposure to negative emotions including mental stress and depression have been associated with reduced endothelial vasoreactivity as measured by BART. Whether mirthful laughter has the opposite effect garnered consideration following the discovery that mu3 opiate receptors were expressed in the vascular endothelium. Because mirthful laughter induces the release of beta-endorphins which in turn have high affinity for mu3 opiate receptors, we hypothesize that such positive emotions lead to the direct release of NO and associated biological consequences. Indeed, our studies have demonstrated opposing effects on endothelial vasoreactivity between those previously established (e.g., mental stress induced by negative visual and/or auditory stimuli) and those induced after mirthful laughter, thereby providing a potential mechanistic link between positive emotions and beneficial effects on the vasculature. This article reviews the relevant physiology and comments on the potentially wider clinical implications in the integration of this process to improve vascular health.

Modulation of vascular endothelial function by low-density lipoprotein cholesterol with aging: influence of habitual exercise

BACKGROUND

Aging is associated with reduced endothelium-dependent dilation (EDD) and increased risk for cardiovascular disease (CVD), but the mechanisms are incompletely understood. Clinically elevated plasma low-density lipoprotein cholesterol (LDL-C) is associated with impaired EDD. The purpose of this study was to determine whether circulating LDL-C within the "normal" range modulates EDD in healthy older adults and whether young age or habitual aerobic exercise protects against this adverse effect.

METHODS

In 83 healthy men with optimal/near optimal LDL-C (<130 mg/dl) or borderline high LDL-C (130-159 mg/dl), EDD (brachial artery flow-mediated dilation, FMD), and endothelium-independent dilation (sublingual glyceryl trinitrate, GTN) were assessed.

RESULTS

FMD was 35% lower in older nonexercising men with borderline high LDL-C vs. optimal/near optimal LDL-C (3.1 +/- 0.5 vs. 4.8 +/- 0.4%Delta, P < 0.05), whereas the GTN response did not differ (P = 0.86). In contrast, FMD was similar between groups of young nonexercising men and between groups of older exercising men differing in LDL-C (P = 0.89-0.95). FMD was inversely related to LDL-C among the older nonexercising men (r = -0.43, P < 0.001), whereas there was no relation in the other groups (P > 0.05).

CONCLUSIONS

Borderline high plasma LDL-C is associated with impaired EDD in older sedentary men, but not in young sedentary or older exercising men. Thus, modest elevations in plasma LDL-C within the normal range may contribute to the increased risk of CVD in sedentary older men by exacerbating vascular endothelial dysfunction, whereas resistance to this adverse influence may help explain the enhanced endothelial function and reduced CVD risk associated with young age and regular aerobic exercise.

Arterial stiffness: a modifiable cardiovascular risk factor?

The subject of arterial stiffness as a modifiable risk factor is controversial and difficult to understand. The best approach here will be to assist readers to understand the issue and the basis of controversy. We also hope to show that the subject is not as overwhelming as it might appear. We believe that new blood is required in this field and that a basic understanding is necessary for researchers to be induced to take on such investigations. Our approach sets out a historic and pathophysiologic background on which modern studies can be based; describes measures and indices of arterial stiffness including pulse wave velocity, augmentation index, ambulatory arterial stiffness index, aortic impedance, and carotid elastic modulus; and finally, addresses the specifics of this interesting and important question. Although aortic stiffening with age is attributable to fracture of elastin lamellae and is largely irreversible, stiffening of muscular arteries can be modified by vasodilator drugs, and by improved endothelial function such as induced by exercise training.

Functional foods and physical activities in health promotion of aging people

Foods contain many bioactive compounds that can improve humans' health, helping to decrease the risk of cataract, macular degeneration, cardiovascular and neurological diseases, osteoporosis, and cancer. Regular practice of exercise and physical activity could also help to drive away aging-associated diseases (obesity, osteoporosis, type 2 diabetes, hypertension, Alzheimer's disease, Parkinson's disease, dementia, and stroke). Exercise recommendations to promote both women's and men's health and disease conditions that hinder exercise practice are described. Health promotion practices should focus on both dietary intake of functional foods and regular practice of exercise within the framework of a healthy lifestyle.

Health behaviors and endothelial function

An unhealthy lifestyle, including excess caloric intake, lack of exercise, smoking, and excessive alcohol consumption, increases one's risk of developing cardiovascular disease (CVD). However, the exact mechanisms by which these behaviors influence the development and progression of CVD have yet to be determined. Endothelial function (EF) has been shown to be a potent predictor of CVD, yet the effects of health behaviors on EF are not clear. The literature assessing the role of four health behaviors, obesity (a proxy of excess caloric intake), smoking, physical inactivity, and alcohol consumption, on the development of endothelial dysfunction is reviewed. Potential mechanisms through which these behaviors may influence EF are discussed. Smoking, being overweight or obese, and physical inactivity are all associated with decreased EF. A direct causal relationship between these measures and EF is suggested by the fact that improvements in these behaviors leads to parallel improvements in EF. The influence of alcohol consumption is somewhat more contentious, with some studies indicating a dose-response relationship such that those with greater consumption have poor EF. However, other studies have shown that those who drink moderately have the best EF. Although there is a growing body of literature implicating poor health behaviors in the development of endothelial dysfunction, more work is needed to establish the exact mechanisms by which this occurs. To our knowledge, there are no studies that have assessed the impact of multiple health behaviors or the interaction of health behaviors on EF.

Short-term increases in intraluminal pressure reverse age-related decrements in endothelium-dependent dilation in soleus muscle feed arteries

We tested the hypothesis that short-term increases in intraluminal pressure improve endothelium-dependent dilation and increase endothelial nitric oxide (NO) synthase (eNOS) expression in senescent soleus muscle feed arteries (SFA). SFA isolated from young (4 mo) and old (24 mo) Fischer 344 rats were cannulated and pressurized at 90 (p90) or 130 (p130) cmH(2)O for 4 h. At the end of the 4-h protocol, pressure in p130 SFA was lowered to 90 cmH(2)O for examination of endothelium-dependent (flow- or ACh-induced) vasodilation. Flow- and ACh-induced dilations were blunted in old p90 SFA relative to young p90 SFA. Pretreatment with increased pressure (p130) improved flow- and ACh-induced dilations in old SFA, such that vasodilator responses were similar to those in young SFA. In the presence of N(omega)-nitro-l-arginine (l-NNA) or l-NNA + indomethacin (Indo), flow-induced dilation was inhibited in old p130 SFA, such that the response was not greater than the response in old p90 SFA. In old p130 SFA, ACh-induced dilation was inhibited by l-NNA + Indo (not l-NNA alone). In a separate experiment, SFA were pressurized at 70, 90, 110, or 130 cmH(2)O for 4 h, and eNOS mRNA and protein content were assessed. Increased pressure induced eNOS mRNA expression in young (not old) SFA. eNOS protein content was not altered in young or old SFA. These results indicate that short-term increases in intraluminal pressure improve endothelium-dependent dilation in senescent SFA, in part by enhancing NO bioavailability; however, the beneficial effect was not associated with increased eNOS expression.

The aging of the heart and blood vessels: a consideration of anatomy and physiology in the era of computed tomography, magnetic resonance imaging, and positron emission tomographic imaging methods with special consideration of atherogenesis

Physicians have long told their patients that the doctor's job is to help patients "get as old as they can." As physicians, we have been aided in this objective by many other scientists in other disciplines. The entity of aging and its related changes blends imperceptibly with a variety of age-related diseases. However, these entities do appear to be separate though interrelated. Curing disease is important and a goal that we all work toward to add years to life expectancy. Here, we consider aging as it affects the heart and great vessels and as it serves to influence and support, if not cause, age-related cardiac diseases. This relationship is drawn as cardiac mechanics, hemodynamics, perfusion, metabolism and innervation, anatomy, and pathophysiology are each considered. The effects of aging are presented in 2 sections related to the early and recent "spikes" in aging related information. The latter is largely based in recent developments in chemistry, genetic engineering, molecular biology and the new imaging methods. The purpose of this manuscript is to present these new imaging methods, especially PET, and their impact on the second "spike." This is emphasized particularly in the second half of this review. As a method of demonstrating these imaging tools and their finest potential application, we decided to "showcase" atherosclerosis as the age-related disease for which these methods have made their greatest impact, for which yet more is promised, and for which the influence on longevity is most obvious. The application of positron emission tomography and other imaging methods to the characterization and image identification of atherosclerotic plaques and particularly the "vulnerable" plaque is emphasized. Yet, even with the eradication of coronary disease, the potential for very long life would not be likely. Only with the identification and eradication of the causative factors of aging can this possibility have a chance of becoming reality.

Functional and Structural Vascular Remodeling in Elite Rowers Assessed by Cardiovascular Magnetic Resonance

OBJECTIVES

We aimed to noninvasively quantify the effects of chronic exercise training on both peripheral and central conduit artery function and structure with high-resolution magnetic resonance imaging (MRI).

BACKGROUND

Physical activity has well-known beneficial effects on vascular function in subjects with endothelial dysfunction. Exercise also leads to beneficial effects on endothelial function in elderly athletes, possibly contributing toward the reduced risk from coronary artery disease in this age group. However, conflicting data exist on the training effects in the younger population.

METHODS

A total of 49 young (age 20 to 35 years) nonsmoking subjects, comprising elite rowers and age- and gender-matched sedentary control subjects, underwent MRI (1.5-T). The ascending, the proximal descending, and the distal descending aorta, and the common carotid artery and the brachial artery were assessed for diastolic and systolic area and distensibility. Endothelial-dependent and -independent brachial artery dilatation were also assessed by cine MRI.

RESULTS

Rowers showed vascular remodeling with enlarged brachial (by 51%, p < 0.001) and reduced central conduit artery cross-sectional areas (by up to 28% [e.g., distal descending aorta], p < 0.001). Vessel distensibilities (mm Hg(-1)) were similar for elite rowers when compared with sedentary control subjects at all levels of the aorta and the carotid and brachial artery (p > 0.05 for all). Endothelial-dependent dilation (percentage and mm2) was similar for rowers and control subjects (p > 0.05). However, rowers showed reduced absolute (by 33%) endothelial-independent dilation (p < 0.001).

CONCLUSIONS

Young elite rowers demonstrate normal endothelial-dependent but reduced endothelial-independent dilation. Chronic, whole body, combined endurance- and strength-training does not lead to changes in arterial stiffness but to vascular remodeling.

Myocardial and peripheral vascular functional adaptation to exercise training

Exercise training seems to restore impaired vascular function in both peripheral and myocardial vessels in patients with coronary artery and peripheral vascular disease or in patients with risk factors for these diseases. However, the results on the effects of exercise training on vascular function in apparently healthy subjects are controversial. We studied the effects of long-term volitionally increased physical activity on peripheral and myocardial vascular function in nine young healthy male monozygotic twin pairs discordant for physical activity and fitness. The brothers were divided into more (MAG) and less active groups according to physical activity and fitness. The difference between groups in VO(2max) was 18+/-10% (P<0.001). Myocardial perfusion at rest, during adenosine-induced vasodilatation and during cold-pressor test and myocardial oxygen consumption were measured with positron emission tomography. In addition, endothelial function was measured using ultrasound in brachial and left anterior descending coronary arteries, and standard echocardiographic measures were taken. No differences were observed in myocardial perfusion measurements between groups. MAG tended to have a lower oxygen extraction fraction (P=0.06), but oxygen consumption was similar between the groups. No differences were found in coronary artery, myocardial resistance vessel or peripheral endothelial function between groups. These results suggest that when the effects of heredity are controlled, myocardial perfusion reserve and endothelial function, both in peripheral arteries and myocardial vessels, are not enhanced by increased physical activity and fitness in young healthy adult men.

Endothelial function in post-menopausal former elite athletes

OBJECTIVE

To characterize endothelial function in postmenopausal former elite athletes in comparison to sedentary controls and to study the influence of hormone replacement therapy (HRT) on endothelial function in these groups of women.

DESIGN

Cross-sectional study.

SETTING

Research unit at a university hospital.

PARTICIPANTS

Twenty postmenopausal former elite but still active endurance female athletes and 19 age-matched sedentary controls. The group of athletes and control subjects were each subdivided into two groups on the basis of utilization or non-utilization of HRT involving estrogen and gestagen.

METHODS

Flow-mediated vasodilatation (FMD) was employed as an indicator of endothelial function. Fasting blood samples were analyzed for lipids and body composition determined by dual-energy x-ray absorptiometry.

MAIN OUTCOME MEASURES

FMD, blood lipids and body composition.

RESULTS

Former elite athletes not utilizing HRT demonstrated the highest FMD of all four subgroups, their values being significantly higher than those of control subjects not utilizing HRT (P < 0.05), whereas this difference was not seen between the subgroups of athletes and control subjects using HRT. Serum levels of cholesterol and low-density lipoprotein (LDL) and the percentage of fat mass were significantly lower in the former elite athletes than in the control group (P < 0.05 in all cases). However, these variables were not related to FMD.

CONCLUSION

This investigation documents enhanced endothelial function in postmenopausal former elite endurance athletes not utilizing HRT, whereas the use of HRT equalizes FMD in former athletes and sedentary control subjects. Our findings suggest that long-term strenuous exercise has beneficial effects on endothelial function in postmenopausal women but that no further improvement can be obtained with HRT.

Effects of different dietary protein intakes on body composition and vascular reactivity

OBJECTIVE

To assess the effects of a diet rich in protein of animal origin in comparison to one with a protein intake of about 15% of the total daily calories on body composition and arterial function.

DESIGN

Randomized prospective study with parallel groups. Body weight (BW), blood pressure (BP), main parameters of carbohydrate and lipid metabolism, body mass composition by bioelectrical impedance analysis, forearm blood flow at rest and in the postischaemic phase by strain gauge plethysmography and flow-mediated dilation of the brachial artery by echography were measured at baseline and after 6 months of the dietary intervention.

SUBJECTS

In total, 15 clinically healthy male volunteers, regularly performing a mixed training three times weekly for 90 min.

INTERVENTION

The participants were randomly prescribed a diet with high (1.9 g/kg BW) or normal (1.3 g/kg BW) protein content.

STATISTICAL ANALYSIS

Differences between means were evaluated by the t-tests for paired or unpaired data and by one way analysis of variance. The strength of correlation between variables was investigated by bivariate Pearson correlation.

RESULTS

Serum cholesterol significantly decreased with both diets in comparison to baseline values, whereas BW was slightly but significantly reduced only by the high-protein (HP) diet. No change was detected in BP and the other metabolic parameters. Body mass composition was not significantly modified by either diet. On the other hand, postischaemic flow-mediated dilation of the brachial artery was enhanced by the sole normal protein (NP) diet, whereas no change in the forearm blood flow, both at rest and in the postischaemic phase, was detected.

CONCLUSIONS

These preliminary results indicate that HP diet was found to be not useful in increasing the muscle mass in comparison to a NP intake. In contrast to this, the latter diet seems to enhance the endothelial function of the arterial vessels with a more pronounced dilatation of the lumen in response to the increase in blood flow.

Augmentation of endothelial function following exercise training is associated with increased L-arginine transport in human heart failure

We have reported previously a decrease in the clearance of the NO (nitric oxide) precursor L-arginine in the forearm circulation of CHF (congestive heart failure) patients, suggesting a potential rate-limiting mechanism contributing to the common finding of endothelial dysfunction in CHF. Given data that show exercise training augments endothelial function in CHF, the aim of the present study was to investigate whether these improvements were due to an increase in L-arginine transport. Measures of L-arginine transport, endothelial function and exercise capacity were repeated before and after 8 weeks of ‘usual living’ or exercise training in 21 CHF patients [NYHA (New York Heart Association) class II/III]. Exercise capacity (6-min walk test) increased following exercise training (496±21 to 561±17 m; P=0.005), whereas the control group demonstrated no change [488±18 to 484±21 m; P=ns (not significant)]. Basal FBF (forearm blood flow) remained stable following exercise training (2.68±0.55 to 2.46±0.32 ml·min−1·100 ml−1 of tissue) and ‘usual living’ (2.16±0.37 to 2.91±0.55 min−1·100 ml−1 of tissue). FBF responses to ACh (acetylcholine) increased following exercise by 49.6±17.7% (area under curve; P=0.01) demonstrating augmented endothelial function. FBF responses to SNP (sodium nitroprusside) were also improved following exercise training (30.8±8.2%; P=0.02). There was no change in vascular function in the ‘usual living’ group. The clearance of L-arginine was significantly increased following involvement in the exercise programme (69.4±7.8 to 101.0±9.5 ml/min; P=0.04), whereas there was no change in the ‘usual living’ group (78.4±17.5 to 81.0±14.9 ml/min; P=ns). In conclusion, the augmentation in endothelial function observed following exercise may be due, in part, to an increase in the transport of L-arginine in CHF patients.

Vascular adaptation to 4 wk of deconditioning by unilateral lower limb suspension

Physical inactivity or deconditioning is an independent risk factor for atherosclerosis and cardiovascular disease. In contrast to exercise, the vascular changes that occur as a result of deconditioning have not been characterized. We used 4 wk of unilateral lower limb suspension (ULLS) to study arterial and venous adaptations to deconditioning. In contrast to previous studies, this model is not confounded by denervation or microgravity. Seven healthy subjects participated in the study. Arterial and venous characteristics of the legs were assessed by echo Doppler ultrasound and venous occlusion plethysmography. The diameter of the common and superficial femoral artery decreased by 12% after 4 wk of ULLS. Baseline calf blood flow, as measured by plethysmography, decreased from 2.1 ± 0.2 to 1.6 ± 0.2 ml·min−1·dl tissue−1. Both arterial diameter and calf blood flow returned to baseline values after 4 wk of recovery. There was no indication of a decrease in flow-mediated dilation of the superficial femoral artery after ULLS deconditioning. This means that functional adaptations to inactivity are not simply the inverse of adaptations to exercise. The venous pressure-volume curve is shifted downward after ULLS, without any effect on compliance. In conclusion, deconditioning by 4 wk of ULLS causes significant changes in both the arterial and the venous system.

Shear stress induces eNOS mRNA expression and improves endothelium-dependent dilation in senescent soleus muscle feed arteries

We tested the hypothesis that increased intraluminal shear stress induces endothelial nitric oxide (NO) synthase (eNOS) mRNA expression and improves endothelium-dependent dilation in senescent soleus muscle feed arteries (SFA) by increasing NO production. SFA were isolated from young (4 mo) and old (24 mo) male Fischer 344 rats and cannulated with two resistance-matched glass micropipettes. SFA were exposed to no flow (NF), low flow (LF), intermediate flow (IF), or high flow (HF) for 4 h. Mean intraluminal shear stress ranged from 0 to 82 dyn/cm2. At the end of the 4-h treatment period, eNOS mRNA expression was assessed in each SFA. eNOS mRNA expression was significantly lower in old NF SFA than in young NF SFA. In old SFA, eNOS mRNA expression was induced by IF (+154%) and HF (+136%), resulting in a level of expression that was not different from that of young SFA. In a separate series of experiments, SFA were pretreated with NF or HF for 4 h, and endothelial function was assessed by examining vasodilator responses to ACh. ACh-induced dilation was less in old NF SFA than young NF SFA. Pretreatment with HF improved ACh-induced dilation in old SFA such that the response was similar to that of young SFA. In the presence of Nω-nitro-l-arginine to inhibit NOS, ACh-induced dilation was inhibited in old HF SFA such that the response was no longer greater than that of old NF SFA. These results indicate that increased intraluminal shear stress induces eNOS mRNA expression and improves endothelium-dependent dilation in senescent SFA by increasing NO production.

Aerobic exercise performance correlates with post-ischemic flow-mediated dilation of the brachial artery in young healthy men

In older healthy men, aerobic exercise capacity is related to postischemic flow-mediated dilation of the brachial artery (FMD), but corresponding data in a younger population is not available. In addition, whether submaximal aerobic exercise performance also correlates with this kind of vasomotor reactivity is not known. Therefore, in 15 nonsmoking young healthy men [age 27 (5) years; body mass index: 24 (2) kg/m(2); mean (SD)] with different levels of ordinary physical activity, but not performing upper-extremity training, we measured FMD at 1 min after reactive hyperemia, and pulmonary oxygen uptake (VO(2)) at ventilatory anaerobic threshold (VO(2)AT) and at peak effort (peak VO(2)) during an incremental exercise on a treadmill. In our participants, FMD was 9.1 (3.4)%, VO(2)AT was 40.72 (5.92) ml/kg per min, and peak VO(2) was 52.95 (8.13) ml/kg per min. Using bivariate Pearson's correlation, and in separate multivariate regression analyses, VO(2)AT and peak VO(2) showed a significant and reasonably good correlation with FMD (r = 0.84, P < 0.001 and r = 0.77, P = 0.001, respectively), independent of age, body mass index and serum total cholesterol (beta = 0.77, P < 0.001, R(2) of the overall model = 0.79 and beta = 0.70, P < 0.005, R(2) of the overall model = 0.69, respectively). Our data provide evidence suggesting that in young healthy men a higher submaximal and maximal aerobic exercise performance is associated with a greater FMD of peripheral conduit arteries.

Effect of acute and chronic ascorbic acid on flow-mediated dilatation with sedentary and physically active human ageing

Peripheral conduit artery flow-mediated dilatation decreases with ageing in humans. The underlying mechanisms and efficacy of preventive strategies are unknown. Brachial artery flow-mediated dilatation was determined at baseline and after ascorbic acid (vitamin C) intravenous infusion and chronic supplementation (500 mg day(-1) for 30 days) in three groups of healthy men: young sedentary (n= 11; 25 +/- 1 years, mean +/-s.e.m.), older sedentary (n= 9; 64 +/- 2), and older endurance-exercise trained (n= 9; 64 +/- 2). At baseline, flow-mediated dilatation (normalized for the hyperaemic stimulus) was approximately 45% lower in the older (0.015 +/- 0.001) versus young (0.028 +/- 0.004) sedentary men (P < 0.01), but was preserved in older exercising men (0.028 +/- 0.004). Ascorbic acid infusion increased plasma concentrations > 15-fold in all groups and restored flow-mediated dilatation in the sedentary older men (to 0.023 +/- 0.002; P > 0.1 versus other groups), with no effects in the other two groups. Oral ascorbic acid supplementation did not affect flow-mediated dilatation in any group. Brachial artery endothelium-independent dilatation (sublingual nitroglycerin) did not differ among the groups at baseline nor change with ascorbic acid administration. These results provide the first evidence for an important role of oxidative stress in both the impairment in peripheral conduit artery flow-mediated dilatation with sedentary human ageing and the preservation of flow-mediated dilatation with physically active ageing.

The effect of physical activity on endothelial function in man

Endothelial dysfunction occurs early in the atherosclerosis in response to elevated atherosclerotic risk factors, and endothelial dysfunction itself may exacerbate the atherosclerotic process. Treatments that reduce atherosclerotic risk factors also generally improve endothelial function. The present review seeks to summarize the effect of exercise training on endothelial function in human subjects. Cross-sectional studies comparing healthy physically active and inactive subjects as well as longitudinal exercise training studies of healthy individuals show little effect of exercise training on endothelial function. In contrast, both cross-section and longitudinal studies document improved endothelial function with exercise training in subjects with abnormal baseline endothelial function, including the elderly and patients with heart failure or coronary artery disease. Improvements in endothelial function with physical activity may explain some of the benefits of exercise in subjects with, or at risk for, vascular disease.