Gender difference in age-related changes in vascular function

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSION

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

Flow-mediated dilatation in the superficial femoral artery is nitric oxide mediated in humans

Flow-mediated dilatation (FMD) of the brachial and radial arteries is an important research tool for assessment of endothelial function in vivo, and is nitric oxide (NO) dependent. The leg skeletal muscle vascular bed is an important territory for studies in exercise physiology. However, the role of endothelial NO in the FMD response of lower limb arteries has never been investigated. The purpose of this study was to examine the contribution of NO to FMD in the superficial femoral artery in healthy subjects. Since physical inactivity may affect endothelial function, and therefore NO availability, spinal cord-injured (SCI) individuals were included as a model of extreme deconditioning. In eight healthy men (34 +/- 13 years) and six SCI individuals (37 +/- 10 years), the 5 min FMD response in the superficial femoral artery was assessed by echo-Doppler, both during infusion of saline and during infusion of the NO synthase blocker N(G)-monomethyl-L-arginine (L-NMMA). In a subset of the controls (n = 6), the 10 min FMD response was also examined using the same procedure. The 5 min FMD response in controls (4.2 +/- 0.3%) was significantly diminished during L-NMMA infusion (1.0 +/- 0.2%, P < 0.001). In SCI, L-NMMA also significantly decreased the FMD response (from 8.2 +/- 0.4% during saline to 2.4 +/- 0.5% during L-NMMA infusion). The hyperaemic flow response during the first 45 s after cuff deflation was lower in both groups during infusion of L-NMMA, but the effect of L-NMMA on FMD persisted in both groups after correction for the shear stress stimulus. The 10 min FMD was not affected by L-NMMA (saline: 5.4 +/- 1.6%, L-NMMA: 5.6 +/- 1.5%). Superficial femoral artery FMD in response to distal arterial occlusion for a period of 5 min is predominantly mediated by NO in healthy men and in the extremely deconditioned legs of SCI individuals.

Endothelial dysfunction and C-reactive protein in relation with the severity of obstructive sleep apnea syndrome

STUDY OBJECTIVES

To investigate flow-mediated dilatation (FMD) and C-reactive protein (CRP) levels in patients with obstructive sleep apnea syndrome (OSAS) in relation with the severity of respiratory disturbances and hypoxemia.

DESIGN

After subjects had completed nocturnal polysomnography, FMD was measured in the brachial artery, and blood samples were obtained to determine serum CRP levels.

SETTING

Sleep laboratory in Seoul National University Bundang Hospital.

PATIENTS

Ninety men: 22 normal controls, 28 subjects with mild to moderate OSAS, and 40 with severe OSAS.

MEASUREMENTS AND RESULTS

FMD was found to be correlated with oxygen desaturation index (ODI), percentage of time below 90% O2 saturation, average O2 saturation, lowest O2 saturation, systolic blood pressure, apnea hypopnea index (AHI), and body mass index. In addition, CRP was correlated with body mass index, waist-to-hip ratio, neck circumference, diastolic pressure, average O2 saturation and percentage of time below 90% O2 saturation but not with AHI. Stepwise multiple regression showed that the ODI was a significant determinant of FMD (adjusted R2 = 10%, beta = -0.33, P < 0.01). In addition, body mass index (beta = 0.25, P < 0.05) and waist-to-hip ratio (beta = 0.21, P < 0.05) were found to be significantly correlated with CRP (adjusted R2 = 12%, P < 0.05), independently of other factors. There was no correlation between FMD and CRP.

CONCLUSION

As a marker of nocturnal hypoxemia, ODI rather than AHI might better explain the relationship between OSAS and FMD. Because body mass index and waist-to-hip ratio were identified as risk factors of high serum CRP in OSAS, obesity should be considered when predicting cardiovascular complications in OSAS.

Flow-mediated dilatation in overweight and obese women with polycystic ovary syndrome

OBJECTIVE

There remains a large degree of disagreement about the association of polycystic ovary syndrome (PCOS) with impaired endothelial dysfunction and cardiovascular disease (CVD) risk. The purpose of this study was to determine whether overweight and obese women with PCOS have impaired endothelial function compared with weight-matched controls without PCOS and whether endothelial function is associated with cardiovascular risk markers and hormonal parameters.

DESIGN

Cross-sectional analysis.

SETTING

An outpatient trial at the Commonwealth Scientific Industrial Research Organisation Clinical Research Unit.

POPULATION

Overweight and obese women with PCOS (n= 12) and weight-matched controls without PCOS (n= 10).

METHODS

Endothelial function, cardiovascular risk markers and hormonal parameters were assessed in the patients.

MAIN OUTCOME MEASURES

Endothelial function was assessed by flow-mediated dilatation (FMD) of the brachial artery using high-resolution ultrasound. Lipid profile, fasting insulin level, glucose level, insulin resistance, C-reactive protein level, folate level, Vitamin B(12) level and hormonal parameters.

RESULTS

Women with PCOS had significantly higher testosterone levels (P < 0.001) and free androgen index (P= 0.006) compared with the controls without PCOS. Both groups were normoinsulinaemic, and there were no significant differences in any of the markers of CVD between women with and without PCOS. Furthermore, FMD was similar in both groups (PCOS 6.1 +/- 1.2% versus control 5.6 +/- 1.0%, P= 0.77).

CONCLUSIONS

Compared with a group of weight-matched women with similar metabolic profiles, normoinsulinemic, overweight and obese women with PCOS did not show any greater impairment in endothelial function assessed by FMD. A normoinsulinemic phenotype of PCOS with low metabolic risk factors may reduce the risk of endothelial dysfunction in overweight and obese women with this syndrome. Further studies are required that directly compare FMD in normoinsulinemic and hyperinsulinaemic women with PCOS.

[Hyperemic reactivity scintigraphy in endothelial function]

OBJECTIVE

The aim of this study was to compare a recently described method to evaluate endothelial function; the hyperemic reactivity scintigraphy (HRS) with the ultrasonographic flow-mediated dilatation (FMD) in brachial artery and its relationship with myocardial SPECT.

METHODS

42 consecutive patients that underwent myocardial scintigraphy were included. Thirty-six patients had simultaneous measurement of FMD. Both studies were obtained after 5 minutes occlusion of the upper arm with a blood pressure cuff inflated at 250 mmHg. HRS was performed dynamically at rate 1 frame/sec during 3 minutes after intravenous injection of 740 MBq of Tc-99 sestamibi. Time-activity curves allowed obtaining the following indexes: medium hyperemic activity/medium contrallateral activity (MHA/MCA) and maximum hyperemic activity/maximum contrallateral activity (MxHA/CxHA).

RESULTS

In 13 patients SPECT was normal. Twenty-nine patients had perfusion defects in scintigraphy. There was relationship between the FMD and the MHA/MCA (r = 0.23; p = 0.018) and the FMD and the MxHA/CxHA (r = 0.18; p = 0.05). Patients with alterations in the SPECT had an index MxHA/CxHA lower than patients with normal SPECT (1.8 +/- 0.2 vs 1.5 +/- 0.4; p = 0.04). We did not find relationship between FMD and alterations in SPECT.

CONCLUSIONS

There is relationship between FMD and HRS. HRS is lower in patients with perfusion defects in the SPECT. HRS could provide additional value to myocardial scintigraphy.

Evidence for reduced sympatholysis in leg resistance vasculature of healthy older women

Inhibition of a sympathetic stimulus (i.e., sympatholysis) during forearm exercise is reduced with age in women. This age-related alteration has not been characterized in the lower extremity vasculature of women, and the potential for blunting of the conduit artery dilatory response to a sudden increase in shear stress [flow-mediated dilation (FMD)] has not been examined in older adults of either sex. In the present study, we assessed popliteal artery diameter and velocity (Doppler ultrasound) in 16 young (23 +/- 1 yr) and 14 older (69 +/- 1 yr) women after 5 min of distal calf occlusion (FMD), 3 min of hand immersion in ice water [cold pressor test (CPT)], and 5 min of distal calf occlusion combined with hand immersion in ice water (FMD+CPT). Peak popliteal conductance after 5-min ischemia was not significantly different in young vs. older women. During the combined stimulus (FMD+CPT), the magnitude of vasoconstriction in the calf (reduction in peak popliteal artery conductance) was similar (5-8%), despite reduced resting adrenergic sensitivity to CPT [young (Y): -27.3 +/- 3.8%; older (O): -15.8 +/- 2.2%; P < 0.05] and blunted muscle sympathetic nerve activity responses to CPT (Y: 12.7 +/- 3.6 bursts/min; O: 7.8 +/- 2.5 bursts/min; P < 0.05) in older women. Popliteal FMD, normalized to the shear stimulus, was attenuated by 60-70% in older women. Peak popliteal diameter, measured during the combined stimulus (FMD+CPT), was blunted in young but not in older women (Y FMD: 5.5 +/- 0.1 mm; Y FMD+CPT: 5.4 +/- 0.1 mm; P = 0.03; O FMD: 5.8 +/- 0.2 mm; O FMD+CPT: 5.8 +/- 0.2 mm). These results confirm previous findings of diminished reactivity in the conduit arteries of older humans and provide the first evidence of reduced sympatholysis in the leg resistance vasculature of older women.

Age and flow-mediated dilation: a comparison of dilatory responsiveness in the brachial and popliteal arteries

Previous investigations of age-associated changes in flow-mediated vasodilation (FMD) in women have been limited to the upper extremity and have not accounted for possible age differences in the stimulus for dilation. The purpose of the present study was to compare age differences in brachial and popliteal FMD and its stimulus (changes in shear rate following occlusion). Ultrasound-derived diameters and Doppler flow velocities of the brachial and popliteal arteries were measured in 14 young (20- to 30-yr-old) and 14 older (60- to 79-yr-old) healthy women at rest and during and after 5 min of distal cuff occlusion. Resting diameters were similar (both P > 0.39) in both age groups. Peak shear rate did not differ with age in either artery: approximately 1,300-1,400 and approximately 400-500 s(-1) in brachial and popliteal arteries, respectively. FMD (percent change above diameter measured during occlusion) was approximately 50-60% lower (P < 0.05) in the brachial (15.8 + 0.8% vs. 8.1 + 1.5%) and popliteal (4.6 +/- 0.7% vs. 1.8 +/- 0.4%) arteries of the older women. The normalized response of the brachial and popliteal arteries (%FMD per unit change in shear rate) was also reduced with age (55% and 53%, respectively) but did not exhibit limb specificity. Additionally, endothelium-independent dilation, as assessed by administration of nitroglycerin, was similarly blunted (by 45-65%) in brachial and popliteal arteries of older women. These results suggest that 1) brachial and popliteal artery FMD (after 5 min of distal occlusion) are similarly reduced with age, 2) when normalized to the change in shear stimulus, both arteries are equally responsive to 5 min of distal cuff occlusion in women, and 3) the age-associated decline in FMD may be attributable in part to diminished smooth muscle responsiveness.

Circadian variation in endothelial function is attenuated in postmenopausal women

OBJECTIVE

The present study was undertaken to investigate the possible existence of an endogenously generated circadian rhythm in endothelial function in women and whether this rhythm is altered after the menopause.

METHODS

Healthy non smoking women (11 pre-menopausal and 13 postmenopausal women) were studied during a 22 h period under constant routine conditions; endothelium-dependent (flow-mediated dilation (%FMD)) and -independent (glyceryl-trintrate (GTN)-mediated) function was assessed every 2 and 4 h, respectively, by high-resolution ultrasound of the brachial artery.

RESULTS

%FMD and %GTN was significantly higher in pre-menopausal women (9.9+/-1.0%FMD (mean+/-S.E.M.); 18.2+/-1.8%GTN; P<0.01) compared with postmenopausal women (6.5+/-0.5%FMD; 11.5+/-1.6%GTN). A significant day-night variation in %FMD was observed pre-menopausal women (day 9.2+/-0.8%; night 10.4+/-1%; P<0.05) with an attenuated rhythm in postmenopausal women (day 6.8+/-0.6%; night 6.0+/-0.4%).

CONCLUSIONS

The findings show a circadian rhythm in %FMD in pre-menopausal women, which disappears after the menopause. The reduction in %FMD and an absence of a day-night variation in %FMD in postmenopausal women may have important implications for the incidence of coronary heart disease in women after the menopause.

Colombian study to assess the use of noninvasive determination of the endothelium-mediated vasodilation (CANDEV) II: does location of the occlusion device affects the accuracy of the diagnosis?

Endothelial dysfunction (ED), which is often evaluated by flow-mediated vasodilation (FMV) in the brachial artery, has been postulated as a predictor of cardiac events. Although the upper and forearm location of the occlusion device have been used for FMV evaluation, currently there is no consensus whether they provide the same information. The main goal of this study was to evaluate if both techniques have the same accuracy to differentiate subjects with and without cardiovascular risk factors (CRFs). A cross-sectional study in 124 subjects was performed. The volunteers were divided in two groups: 62 subjects (20 women and 42 men) with at least one CRF and 62 (20 women and 42 men) healthy subjects without CRFs. FMV measurements using the cuff in the upper arm and forearm with intervals of 30 min were taken. In all subjects, %FMV with the cuff located in the upper arm was 10.13 +/- 4.5 and 9.8 +/- 4.1 with the cuff located below the elbow. In healthy subjects without CRFs the %FMV in the upper arm was 12.19 +/- 4.0 versus 12.31 +/- 3.4 in the upper forearm, in CRF subjects it was 8.08 +/- 4.0 vs 7.29 +/- 3.2., respectively. FMV was not affected by the location of the cuff in maintaining the test ability and accuracy to differentiate subjects with and without CRFs.

Effect of weight loss on inflammatory and endothelial markers and FMD using two low-fat diets

OBJECTIVE

Cardiovascular disease is strongly associated with obesity and there is evidence that weight loss has positive effects on cardiovascular disease risk. The aims of this study were to compare meal replacements (MR) with a conventional low-fat diet as weight loss strategies and to examine the effect of weight loss on flow-mediated dilatation (FMD) and other markers of endothelial function in overweight Australians with raised triglycerides (TG) (> 2 mmol/l).

RESEARCH METHODS

Subjects matched for age, gender, fasting plasma TG and body mass index were randomized to two low- fat high- carbohydrate weight loss strategies (both < 6000 kJ), one using MR and the other a structured eating plan, control (C). Subjects followed both diets for 3 months. In total, 55 subjects completed the study. FMD, pulse wave velocity and blood pressure (BP) were measured at baseline and at 3 months, as were fasting blood samples for lipids, glucose, insulin, C reactive protein (CRP) and endothelium-derived factors.

RESULTS

Mean weight loss was 6.3 +/- 3.7 kg (6.0 +/- 4.2 vs 6.63 +/- 3.35 kg, MR vs C) with no difference between diet groups. TG, insulin, CRP, plasminogen activator inhibitor 1 (PAI-1) and soluble intracellular adhesion molecule-1 (sICAM1) fell after weight loss, but FMD did not change. Systolic BP fell by 8 mmHg and pulse wave velocity improved.

DISCUSSION

In subjects with elevated TG, weight loss resulted in significant improvements in cardiovascular risk markers, particularly endothelium-derived factors (PAI-1 and sICAM1). However, FMD did not improve with weight loss.

Matched Case-Control Study on Factor V Leiden and the Prothrombin G20210A Mutation in Patients With Ischemic Stroke/Transient Ischemic Attack Up to the Age of 60 Years

Background and Purpose— The role of the factor V Leiden mutation ( FVL ) and the G20210A mutation of the prothrombin ( factor II [FII] ) gene for arterial thrombosis is not clear.

Methods— We investigated the prevalence of these mutations in 468 patients with an acute stroke or transient ischemic attack (TIA) before the age of 60 years and in a healthy control population individually matched for age and gender. We also analyzed interactions between the mutations, gender, standard vascular risk factors, and stroke risk.

Results— The prevalence of the FVL did not differ significantly between patients and control subjects. However, we found a significant interaction between the FVL , smoking, and risk of stroke in women: female smokers without FVL had a somewhat increased risk of stroke of 2.6 (95% CI, 1.5 to 4.6; P =0.001) compared with nonsmoking noncarriers of the FVL . Stroke risk was markedly higher in female smokers who had the FVL (OR, 8.8; 95% CI, 2.0 to 38.0; P =0.004) after multivariate adjustment. No such interaction was observed in men. In contrast, the frequency of the FII G20210A mutation was significantly higher in male patients compared with controls (6% versus 1%; adjusted OR, 6.1; 95% CI, 1.3 to 28.3; P =0.021). In females, the prevalence of the mutation was 3% in both groups. We found no significant interactions of the FII G20210A mutation with other vascular risk factors and stroke risk.

Conclusions— Our data indicate a highly increased risk of ischemic cerebrovascular events in women up to 60 years who smoke and have FVL . We also found evidence for an increased risk of stroke/TIA in men who have the FII G20210A mutation but not in women in this age group.

Assessment of flow-mediated vasodilatation (FMD) of the brachial artery: effects of technical aspects of the FMD measurement on the FMD response

AIMS

The ability to assess endothelial function non-invasively with B-mode ultrasound has lead to its widespread application in a variety of studies. However, the absolute values obtained using this approach vary considerably across studies. We studied whether technical aspects of the methodology can explain the wide variety in absolute values across studies.

METHODS AND RESULTS

A literature search was performed to identify published reports on flow-mediated vasodilatation (FMD) of the brachial artery published between 1992 and 2001. Information on type of equipment (wall track/B-mode), location of the measurement (antecubital fossa/upper arm), occlusion site (lower/upper arm), occlusion duration (min), and occlusion pressure was extracted. Patient characteristics were also extracted. For the healthy populations, mean FMD varied from 0.20 to 19.2%; for the coronary heart disease (CHD) patients FMD varied from -1.3 to 14%; for subjects with diabetes mellitus FMD varied from 0.75 to 12%. Compared with occlusion at the upper arm, lower arm occlusion was related to decreased FMD (mean difference in FMD -2.47%; 95% CI 0.55-4.39). An occlusion duration of > or =4.5 min was related to an increased FMD compared with an occlusion time of < or =4 min (mean difference 1.30%; 95% CI 0.35-2.46). These findings were adjusted for other technical aspects of the methodology and for differences in risk factors between populations.

CONCLUSION

Mean FMD differs widely between studies. There is a great overlap between populations (healthy, CHD, diabetics). Our findings suggest that the technical aspects of the measurements, the location, and the duration of the occlusion may explain some of these differences, whereas type of equipment, location of the measurement, and occlusion pressure do not.

Age-related alterations in NOS and oxidative stress in mesenteric arteries from male and female rats

Epidemiological evidence suggests that advancing age affects the cardiovascular system of men and women differently. The purpose of this study was to determine whether the effects of aging on nitric oxide synthase (NOS), oxidative stress, and vascular function are different in males and females. Mesenteric arteries from young (3 mo) and old (24 mo) male and female Fischer 344/Brown Norway rats were studied. Western blot analysis and NOS activity were performed on the homogenized mesenteric arterial bed separated into cytosolic and membrane-associated fractions. Plasma 8-isoprostane measurements assessed oxidative stress. Vascular reactivity was determined by using a wire myograph in the absence and presence of a NOS inhibitor, Nω-nitro-l-arginine, to examine endothelial function and basal and stimulated nitric oxide release. In additional arteries, reactivity was performed in the presence of polyethylene glycol-SOD to assess the impact of superoxide on vascular function. Among females, aging was associated with a decline in membrane-associated NOS activity and membrane-associated NOS III protein expression. Advancing age in males was associated with increased cytosolic NOS III protein expression. Among both males and females, advancing age resulted in increased oxidative stress. Vascular function was maintained with age in arteries from both males and females, and there was no difference in either basal or stimulated nitric oxide release with age. Despite sex-specific effects of advancing age on the NOS system and increases in markers of oxidative stress, vascular function is maintained in mesenteric arteries from aged Fischer 344/Brown Norway rats. These data suggest that age-related alterations in the resistance vasculature are complex and likely involve multiple compensating vasoactive pathways.

Gender influences endothelial-dependent arterial dilatation via arterial size in youth

BACKGROUND

Reduced endothelial-dependent arterial dilatation (EDAD) has been suggested as an early marker of arteriosclerosis, since it has been reported to correlate with known cardiovascular disease (CVD) risk factors. It is unclear, however, whether gender plays a mediating or a moderating role in these relationships. The aim of this study was to evaluate the influence of gender on EDAD in youth at risk for CVD.

METHODS

The sample population of 261 individuals (mean age, 20 yr; SD, 3 yr) consisted of 148 African Americans, 113 European Americans, 133 males, and 128 females, all with a verified family history of CVD (ie, hypertension, myocardial infarction). Anthropometrics, sociometrics, hemodynamics, brachial artery diameter, left ventricular mass, and relative wall thickness were measured and used as independent variables. EDAD (dependent variable) was expressed as percent (%) change of brachial artery diameter to reactive hyperemia induced by pressure cuff occlusion and release. Artery diameters were calculated via an automated border detection system.

RESULTS

Percent EDAD change was inversely related to initial diameter of the brachial artery. Mean percent EDAD change was 14.37% for female subjects compared with 10.48% for male subjects. The gender difference was a function of smaller initial artery size in the female subjects. When initial diameter and gender were considered simultaneously within a multivariate model, the gender effect was eliminated. Although a large prediameter effect remained, the relationship between prediameter and EDAD was greater in female than in male subjects (ie, interaction/moderating effect).

CONCLUSION

The data suggest that the smaller the artery is, the more it will dilate. Further EDAD investigations are needed to predict arteriosclerosis, taking into account of the gender difference in vessel size.

Preserved flow-mediated dilation in the inactive legs of spinal cord-injured individuals

The aim of the study was to assess endothelial function, measured by flow-mediated dilation (FMD), in an inactive extremity (leg) and chronically active extremity (arm) within one subject. Eleven male spinal cord-injured (SCI) individuals and eleven male controls (C) were included. Echo Doppler measurements were performed to measure FMD responses after 10 and 5 min of arterial occlusion of the leg (superficial femoral artery, SFA) and the arm (brachial artery, BA), respectively. A nitroglycerine spray was administered to determine the endothelium independent vasodilatation in the SFA. In the SFA, relative changes in FMD were significantly enhanced in SCI compared with C (SCI: 14.1 +/- 1.3%; C: 9.2 +/- 2.3%), whereas no differences were found in the BA (SCI: 12.5 +/- 2.9%; C: 14.2 +/- 3.3%). Because the FMD response is directly proportional to the magnitude of the stimulus, the FMD response was also expressed relative to the shear rate. No differences between the groups were found for the FMD-to-shear rate ratio in the SFA (SCI:0.061 +/- 0.023%/s(-1); C: 0.049 +/- 0.024%/s(-1)), whereas the FMD-to-shear rate ratio was significantly decreased in the BA of SCI individuals (SCI: 0.037 +/- 0.01%/s(-1); C: 0.061 +/- 0.027%/s(-1)). The relative dilatory response to nitroglycerine did not differ between the groups. (SCI: 15.6 +/- 2.0%; C: 13.4 +/- 2.3%). In conclusion, our results indicate that SCI individuals have a preserved endothelial function in the inactive legs and possibly an attenuated endothelial function in the active arms compared with controls.

Aging and the endothelium

One link between aging and endothelial function is the inflammatory response. On one hand, the latter shortens the biological engaged by activated leukocytes against invaders or stressing agents. On the other hand, the surveyed tissues become targets of the toxicity of reactive oxygen species, ROS. The ensuing regeneration is source of transcriptional infidelity, leading to the alteration of the repaired tissue. Hence, the toll of inflammatory stress consists in premature senescence of cell and tissues. This hypothesis is discussed in the present review, which focuses on the molecular targets relevant for cancer and degenerative diseases, both tributary to an inflammatory environment and taking advantage from the consequences of cell and tissue dysfunctions characteristic of aging. Eventually, adaptation to stress, whatever its origin -inflammatory and/or psychosocial-is discussed. Basal nitric oxide (NO) release, such as provided through moderate exercise, seems to be the most potent guardian against immune, nervous and cardiovascular over-stimulation. Tissue regeneration is also obtained by circulating endothelial progenitors able to recognize the damaged tissue. To avoid post-inflammatory alterations resulting in detrimental changes of tissues and organs, the pharmacological protection of endothelium by agents able to modulate its activation seems crucial to us.

Age-related endothelial dysfunction : potential implications for pharmacotherapy

Aging per se is associated with abnormalities of the vascular wall linked to both structural and functional changes that can take place at the level of the extracellular matrix, the vascular smooth muscle and the endothelium of blood vessels. Endothelial dysfunction is generally defined as a decrease in the capacity of the endothelium to dilate blood vessels in response to physical and chemical stimuli. It is one of the characteristic changes that occur with age, independently of other known cardiovascular risk factors. This may account in part for the increased incidence of cardiovascular events in elderly people that can be reversed by restoring endothelial function. A better understanding of the mechanisms involved and the aetiopathogenesis of this process will help in the search for new therapeutic agents.Age-dependent alteration of endothelium-dependent relaxation seems to be a widespread phenomenon both in conductance and resistance arteries from several species. In the course of aging, there is an alteration in the equilibrium between relaxing and contracting factors released by the endothelium. Hence, there is a progressive reduction in the participation of nitric oxide and endothelium-derived hyperpolarising factor associated with increased participation of oxygen-derived free radicals and cyclo-oxygenase-derived prostanoids. Also, the endothelin-1 and angiotensin II pathways may play a role in age-related endothelial dysfunction. The use of drugs acting at different levels of these signalling cascades, including antioxidant therapy, lipid-lowering drugs and estrogens, seems to be promising.

Cardiovascular risk in women with type 2 diabetes

Type 2 DM appears to eliminate the relative survival advantage experienced by premenopausal nondiabetic women compared with men with regard to CVD. The role of traditional cardiovascular risk factors, while important, cannot fully account for the disparate increase in CVD among women with type 2 DM compared with nondiabetic women. The interplay between type 2 DM and female hormones may prove important. Other less traditional risk factors such as endothelial dysfunction and impaired fibrinolysis may also play a role. Impairments in cardiovascular exercise performance in women with type 2 DM may provide insight in the future as representative of a pre-CVD state. Future research should focus on the specific causes of CVD in women with DM. In the meantime, it is important to aggressively treat modifiable risk factors in this population (Table 1). The impact of this health problem will continue to increase in our aging society, because a steadily increasing proportion of the population will be women; furthermore, an increasing percentage of these women will have diabetes if current trends continue.

Aging, ion channel expression, and vascular function

Cardiovascular disease remains the leading cause of death in the United States, and aging is one of the main risk factors for its development. Coronary arteries nurture the heart, but as age progresses, they suffer changes that make them stiffer, thicker, and with higher spontaneous contractile activity. Even in the absence of pathological atherosclerotic lesions, these changes make the coronary arteries at risk for vasospasm and the individual at risk for myocardial ischemia and heart failure. Thus, knowledge of the molecular mechanisms involved in the vascular physiology, disease, and aging of the coronary circulation is required to develop strategies to preserve the quality of life of an increasingly aging population. One of the key factors that regulate coronary arterial tone is the activity of K+ channels in the vascular smooth muscle cells (SMCs). In particular, voltage-dependent and Ca(2+)-activated K+ (BKCa) channels, which are abundant in the coronary SMCs, are targets of vasoconstrictors and vasorelaxants, and play a key role in determining arterial tone and diameter. Aging induces a reduction in the density of the alpha-subunit of BKCa channels in coronary smooth muscle, lowers baseline endothelial release of the relaxant nitric oxide (NO), and increases the response to endothelial constrictor factors and K+. Thus, aging induces the remodeling of important proteins involved in the excitability and contractility of the coronary circulation. Altogether, these changes increase the risk of coronary artery vasospasm, myocardial ischemia, and infarct in the elderly.

Cardiovascular risk factors as determinants of endothelium-dependent and endothelium-independent vascular reactivity in the general population

OBJECTIVES

We examined to what extent the variation in risk factors for coronary heart disease (CHD) and the Framingham risk score (FRS) explain the variation in vascular reactivity in adults aged 30 to 53 years.

BACKGROUND

The role of risk factors in determining vascular reactivity in the general population has not been quantified.

METHODS

Risk factors for CHD were measured, and the FRS was calculated in 69 healthy volunteers. Lipoprotein particle size was measured using proton-nuclear magnetic resonance spectroscopy. Forearm plethysmography was used to assess blood flow responses to acetylcholine (ACh), bradykinin (BK), glyceryl trinitrate (GTN), noradrenaline and N(G)-monomethyl-L-arginine (L-NMMA).

RESULTS

Lower ACh and BK responses were associated with a higher body mass index (BMI), a higher total cholesterol to high-density lipoprotein (HDL) cholesterol ratio, lower HDL cholesterol and a cigarette smoking habit (all p < 0.05). Higher low-density lipoprotein (LDL) cholesterol was also associated with a lower BK response (p = 0.001). A decreased GTN response was associated with a higher BMI and total cholesterol to HDL cholesterol ratio (both p < 0.05). A decreased L-NMMA response was associated with a smoking habit (p < 0.001). Lipoprotein particle sizes did not independently predict any vascular response. A high FRS was associated with a reduced response to ACh (p = 0.07), BK (p = 0.003) and L-NMMA (p = 0.003), and the relationship was stronger in women than in men. Altogether, risk factors explained 13%, 9%, 8% and 15% of the response to ACh, BK, GTN and L-NMMA, respectively.

CONCLUSIONS

Lipids, BMI and smoking are important determinants of vascular reactivity. The FRS is predictive of agonist-stimulated, endothelium-dependent vasodilation and basal NO release. However, much of the variation in the vascular responses to these drugs, at this age, remains unexplained.