Brachial artery vasomotor function is inversely associated with 24-h ambulatory blood pressure

Dysregulation of miR-637 Is Involved in the Development of Retinopathy in Hypertension Patients and Serves a Regulatory Role in Retinol Endothelial Cell Proliferation

BACKGROUND

MicroRNAs play an important role in the proliferation and migration of retinal endothelial cells in patients with hypertension and hypertensive retinopathy (HR). This study aimed to investigate the clinical value of miR-637 in HR and its role in retinal endothelial cell proliferation and migration.

METHODS

A total of 126 subjects were recruited for the study, including 42 patients with hypertension (male/female 25/17), 42 healthy individuals (male/female 20/22), and 42 cases with HR (male/female 20/22). Except SBP and DBP, there was no significant difference in other indexes among the three groups. Quantitative real-time PCR was used to detect the expression of miR-637. The receiver operating curve (ROC) was used for diagnosis value analysis. Logistic regression analysis was used to evaluate the relationship between miR-637 and HR. CCK-8 and Transwell were used to detect the effect of miR-637 on the proliferation and migration of human umbilical vein endothelial cells.

RESULTS

Compared with hypertensive patients, HR patients had the lowest expression of miR-637. The area under the curve of miR-637 detected by the ROC curve method is 0.892, which has the ability to distinguish hypertension and HR patients. Logistic regression analysis showed that miR-637 was an independent influencing factor in HR. Cell experiment results showed that overexpression of miR-637 significantly inhibited cell proliferation and migration, while downregulation of miR-637 had the opposite effect. Luciferase analysis showed that STAT3 was the target gene of miR-637.

CONCLUSION

Our data indicate that miR-637 is a potential noninvasive marker for patients with HR. The action of miR-637 on STAT3 may inhibit the proliferation and migration of retinal endothelial cells, providing a possible target for the treatment of HR.

The acute effect of coffee on endothelial function and glucose metabolism following a glucose load in healthy human volunteers

A diet rich in plant polyphenols has been suggested to reduce the incidence of cardiovascular disease and type 2 diabetes mellitus, in part, via improvements in endothelial function. Coffee is a rich source of phenolic compounds including the phenolic acid, chlorogenic acid (CGA). The aim of the study was to investigate the effect of coffee as a whole beverage on endothelial function, blood pressure and blood glucose concentration. Twelve healthy men and women were recruited to a randomised, placebo-controlled, cross-over study, with three treatments tested: (i) 18 g of ground caffeinated coffee containing 300 mg CGA in 200 mL of hot water, (ii) 18 g of decaffeinated coffee containing 287 mg CGA in 200 mL of hot water, and (iii) 200 mL of hot water (control). Treatment beverages were consumed twice, two hours apart, with the second beverage consumed simultaneously with a 75 g glucose load. Blood pressure was recorded and the finger prick glucose test was performed at time = 0 and then every 30 minutes up to 2 hours. Endothelial function, assessed using flow-mediated dilatation (FMD) of the brachial artery, was measured at 1 hour and a blood sample taken at 2 hours to measure plasma nitrate/nitrite and 5-CGA concentrations. The FMD response was significantly higher in the caffeinated coffee group compared to both decaffeinated coffee and water groups (P < 0.001). There was no significant difference in the FMD response between decaffeinated coffee and water. Blood glucose concentrations and blood pressure were not different between the three treatment groups. In conclusion, the consumption of caffeinated coffee resulted in a significant improvement in endothelial function, but there was no evidence for benefit regarding glucose metabolism or blood pressure. Although the mechanism has yet to be elucidated the results suggest that coffee as a whole beverage may improve endothelial function, or that caffeine is the component of coffee responsible for improving FMD.

Flavonoid-Rich Apple Improves Endothelial Function in Individuals at Risk for Cardiovascular Disease: A Randomized Controlled Clinical Trial

SCOPE

The cardioprotective effects of apples are primarily attributed to flavonoids, found predominantly in the skin. This study aimed to determine if acute and/or chronic (4 weeks) ingestion of flavonoid-rich apples improves endothelial function, blood pressure (BP), and arterial stiffness in individuals at risk for cardiovascular diseases (CVD).

METHODS AND RESULTS

In this randomized, controlled cross-over trial, acute and 4 week intake of apple with skin (high flavonoid apple, HFA) is compared to intake of apple flesh only (low flavonoid apple, LFA) in 30 participants. The primary outcome is endothelial function assessed using flow-mediated dilation (FMD) of the brachial artery, while main secondary outcomes are 24 h ambulatory BP and arterial stiffness. Other outcomes include fasting serum glucose and lipoprotein profile, plasma heme oxygenase-1 (Hmox-1), F₂ -isoprostanes, flavonoid metabolites, and plasma and salivary nitrate (NO₃^- ) and nitrite (NO₂^- ) concentrations. Compared to LFA control, the HFA results in a significant increase in FMD acutely (0.8%, p < 0.001) and after 4 weeks chronic intake (0.5%, p < 0.001), and in plasma flavonoid metabolites (p < 0.0001). Other outcomes are not altered significantly.

CONCLUSION

A lower risk of CVD with higher apple consumption could be mediated by the beneficial effect of apple skin on endothelial function, both acutely and chronically.

Acute effects of chlorogenic acids on endothelial function and blood pressure in healthy men and women

Coffee is a rich source of polyphenols, primarily chlorogenic acids (CGA). Certain polyphenols and polyphenol-rich foods and beverages have been shown to improve endothelial function and lower blood pressure (BP). The aim of the present study was to investigate the acute effect of two doses of CGA (5-CGA) on endothelial function and BP. In a cross-over study, 16 healthy men and women received: (i) 0 mg purified 5-CGA (control group); (ii) 450 mg purified 5-CGA; (iii) 900 mg purified 5-CGA; and (iv) 200 mg purified (-)-epicatechin (positive control) in random order one week apart. Peak and continuous mean (60 to 240 s post ischaemia) flow-mediated dilation (FMD) was measured at baseline, 1 h and 4 h. BP was measured at baseline and every 30 min to 4 h. Plasma CGA and epicatechin levels were significantly increased at both 1 h and 4 h post their respective treatments. Peak FMD was not significantly altered by either dose of 5-CGA or the epicatechin, relative to control (p > 0.05). Relative to control, effects on continuous mean FMD response following 450 mg 5-CGA and 900 mg of 5-CGA (0.47 ± 0.16%, p = 0.016 and 0.65 ± 0.16%, p < 0.001, respectively) at 1 h and (0.18 ± 0.17%, p = 0.99 and 0.44 ± 0.16%, p < 0.05, respectively) at 4 h. There was no significant effect of any of the treatments on BP. In conclusion, the present study has found no significant effect of 5-CGA, at 450 and 900 mg, on peak FMD response. However, there were significant improvements in mean post-ischaemic FMD response, particularly at the 1 h time point in this group of healthy individuals.

Endothelial function in postmenopausal women with nighttime systolic hypertension

OBJECTIVE

Hypertension becomes more prevalent in women during their postmenopausal years. Nighttime systolic blood pressure (SBP) is especially predictive of adverse cardiac events, and the relationship between rising nighttime SBP and cardiovascular risk increases more rapidly in women compared with men. The reasons for the prognostic significance of nighttime SBP are not completely known but may involve vascular endothelial dysfunction. The purposes of this study were to examine the relationship between nighttime SBP and endothelial function, as assessed by brachial artery flow-mediated dilation (FMD), and to determine whether postmenopausal women with nighttime hypertension (SBP ≥120 mm Hg) evidenced greater endothelial dysfunction compared with women with normal nighttime SBP.

METHODS

One hundred postmenopausal women (mean [SD] age, 65.8 [7.5] y; mean [SD] body mass index, 28.3 [4.7] kg/m; hypertension, 47%; coronary artery disease, 51%; mean [SD] clinic SBP, 137 [17] mm Hg; mean [SD] clinic diastolic blood pressure, 67 [11] mm Hg; nighttime hypertension, 34 women) underwent 24-hour ambulatory blood pressure monitoring, actigraphy, and brachial artery FMD assessment.

RESULTS

Multivariate regression models showed that higher nighttime SBP and larger baseline artery diameter were inversely related to FMD. Nighttime SBP and baseline artery diameter accounted for 23% of the variance in FMD. After adjustment for baseline artery diameter, women with nighttime hypertension had lower mean (SD) FMD than women with normal nighttime SBP (2.95% [0.65%] vs 5.52% [0.46%], P = 0.002).

CONCLUSIONS

Nighttime hypertension is associated with reduced endothelial function in postmenopausal women. Research examining the therapeutic benefits of nighttime hypertension treatment on endothelial function and future cardiovascular risk in postmenopausal women is warranted.

Are increased carotid artery pulsatility and resistance indexes early signs of vascular abnormalities in young obese males?

PURPOSE

To provide insight into the factors by which obesity in itself may directly lead to early arterial damage, we aimed to determine early sonographic markers of obesity-related vascular dysfunction in young obese males.

METHODS

Thirty-five young obese males and 23 age-matched healthy male volunteers were recruited into the study. Common carotid artery pulsatility index and resistance index were calculated from blood flow velocities curves obtained by pulsed Doppler ultrasonography.

RESULTS

The mean pulsatility index, resistance index, body mass index, waist circumference, systolic and diastolic blood pressure, homeostasis model assessment for insulin resistance, plasma fasting glucose, insulin, C-peptide, triglycerides, low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein were statistically higher in obese subjects than in healthy controls.

CONCLUSIONS

Our results suggest that depressed vessel compliance and increased vascular resistance are features of young, obese, normotensive subjects independently of and in addition to cardiovascular risk factors. As changes in arterial wall properties may be incipient in young obese subjects, future studies will be required to demonstrate whether early intervention such as diet and exercise in this population can improve vascular functions.

Effect of soy isoflavones on blood pressure: a meta-analysis of randomized controlled trials

BACKGROUND AND AIM

The effect of soy isoflavones on blood pressure is controversial. The objective of this study was to evaluate the effect of dietary soy isoflavones on blood pressure.

METHODS AND RESULTS

Trials were searched in PubMed, the Cochrane Library, Embase and references cited in related reviews and studies. A total of eleven trials were reviewed. Meta-analysis results showed a mean decrease of 2.5 mm Hg (95% CIs, - 5.35 to 0.34 mm Hg; P = 0.08) for systolic blood pressure and 1.5 mm Hg (95% CIs, - 3.09 to 0.17 mm Hg; P = 0.08) for diastolic blood pressure in the soy isoflavones-treated group compared to placebo. Meta-regression and subgroup analyses indicated that blood pressure status was a significant predictor of heterogeneity for the effect of soy isoflavones on blood pressure. Subgroup analysis of hypertensive subjects revealed that a greater blood pressure reduction was identified in the soy isoflavone-treated group compared to placebo (5 trials; SBP: - 5.94, 95% CIs [- 10.55, - 1.34] mm Hg, P = 0.01; DBP: - 3.35, 95% CIs [- 6.52, - 0.19] mm Hg, P = 0.04). In contrast, treatment with soy isoflavones did not lead to a significant reduction in blood pressure in normotensive subjects (6 trials; SBP: 0.29, 95% CIs [- 2.39, 2.97] mm Hg, P = 0.83; DBP: - 0.43, 95% CIs [- 1.66, 0.81] mm Hg, P = 0.50).

CONCLUSION

Soy isoflavones had an effect of lowering blood pressure in hypertensive subjects, but not in normotensive subjects. Larger trials need to be carried out to confirm the present findings.

Intravital microscopy reveals endothelial dysfunction in resistance arterioles in Angiotensin II-induced hypertension

It is known that hypertension is associated with endothelial dysfunction and that Angiotensin II (Ang II) is a key player in the pathogenesis of hypertension. We aimed to elucidate whether endothelial dysfunction is a specific feature of Ang II-mediated hypertension or a common finding of hypertension, independently of underlying etiology. We studied endothelial-dependent vasorelaxation in precapillary resistance arterioles and in various large-caliber conductance arteries in wild-type mice with Ang II-dependent hypertension (2-kidney 1-clip (2K1C) model) or Ang II-independent (volume overload) hypertension (1-kidney 1-clip model (1K1C)). Normotensive sham mice were used as controls. Aortic mechanical properties were also evaluated. Intravital microscopy of precapillary arterioles revealed a significantly impaired endothelium-dependent vasorelaxation in 2K1C mice compared with sham mice, as quantified by the ratio of acetylcholine (ACh)-induced over S-nitroso-N-acetyl-D,L-penicillamine (SNAP)-induced vasorelaxation (2K1C: 0.49±0.12 vs. sham: 0.87±0.11, P=0.018). In contrast, the ACh/SNAP ratio in volume-overload hypertension 1K1C mice was not significantly different from sham mice, indicating no specific endothelial dysfunction (1K1C: 0.77±0.27 vs. sham: 0.87±0.11, P=0.138). Mechanical aortic wall properties and endothelium-dependent vasorelaxation, assessed ex vivo in rings of large-caliber conductance (abdominal and thoracic aorta, carotid and femoral arteries), were not different between 2K1C, 1K1C and sham mice. Endothelial dysfunction is an early feature of Ang II- but not volume-overload-mediated hypertension. This occurs exclusively at the level of precapillary arterioles and not in conduit arteries. Our findings, if confirmed in clinical studies, will provide a better understanding of the pathophysiological mechanisms of hypertension.

Influence of systolic blood pressure and cigarette smoking on endothelial function in young healthy people

BACKGROUND

Flow-mediated dilatation (FMD) of the brachial artery represents systemic endothelial function, so the relationship between FMD and blood pressure (BP) profile, in relation to the effects of cigarette smoking, was investigated in young healthy subjects.

METHODS AND RESULTS

The 62 healthy subjects (14 females, 48 males; mean 29.7+/-5.5 years old), were divided into a smoking group (n=30) and non-smoking group (n=32). FMD was induced by reactive hyperemia. It was lower in the smoking group than in the non-smoking group (P<0.05). In the non-smoking group, there was an inverse correlation (r=-0.59, P<0.0005) between FMD and systolic BP (SBP), which was not recognized in the smoking group. Multiple stepwise regression analysis revealed that FMD was predicted by either the SBP or the brachial artery diameter in the non-smoking group, whereas it was predicted by the brachial artery diameter in the smoking group. Subdivision by cut-off value of SBP =120 mmHg demonstrated that although FMD with SBP <120 mmHg was preserved in subjects in the non-smoking group, it was depressed to a level comparable with SBP >or=120 mmHg in the smoking group.

CONCLUSIONS

Highly-preserved FMD in subjects with SBP <120 mmHg appears to be impaired by cigarette smoking, resulting in a loss of association between FMD and SBP.

Endothelial progenitor cells, endothelial dysfunction, inflammation, and oxidative stress in hypertension

With a prevalence in excess of 20%, hypertension is a common finding among Western adult populations. Hypertension is directly implicated in the pathophysiology of various cardiovascular disease states and is a significant contributor to ill health, leading to an excess of both morbidity and mortality. The etiology of hypertension has been explored in depth, but the pathophysiology is multifactorial, complex, and poorly understood. Recent interest has been directed toward investigating the purported role of the endothelium, which acts as an important regulator of vascular homeostasis. Endothelial dysfunction is now recognized to occur in hypertension, regardless of whether the etiology is essential or secondary to endocrine or renal processes. Nitric oxide (NO) is a volatile gas produced by endothelial cells that acts to maintain vascular tone. Reduced bioavailability of NO appears to be the key process through which endothelial dysfunction is manifested in hypertension. The result is of an imbalance of counteracting mechanisms, normally designed to maintain vascular homeostasis, leading to vasoconstriction and impaired vascular function. It has become increasingly apparent that these changes may be effected in response to enhanced oxidative stress, possibly as a result of systemic and localized inflammatory responses. This article provides an overview of endothelial dysfunction in hypertension and focuses on the purported role of oxidative stress and inflammation as the catalysts for this process.

A single nucleotide polymorphism in the CYP4F2 but not CYP4A11 gene is associated with increased 20-HETE excretion and blood pressure

Arachidonic acid is a major fatty acid that can be metabolized by the cytochrome P450 enzyme to a number of bioactive eicosanoids. A major metabolite of this oxidation is 20-hydroxyeicosatetraenoic acid, which acts as a potent vasoconstrictor. However, in the kidney, its vasoconstrictor actions can be offset by its natriuretic properties. A guanine-to-adenine polymorphism in the CYP4F2 gene was associated with a reduction in 20-hydroxyeicosatetraenoic acid production in vitro. A thymidine-to-cytosine polymorphism in the CYP4A11 gene reduced catalytic activity by >50% in vitro and was associated with hypertension. The aim was to determine whether these 2 mutations are associated with urinary 20-hydroxyeicosatetraenoic acid excretion and blood pressure in humans. For the CYP4F2, 51% were homozygous for the G allele, 40% were carriers, and 9% were homozygous for the A allele. For CYP4A11, 72% were homozygous for the T allele, 25% were carriers, and 3% were homozygous for the C allele. The CYP4F2 GA/AA genotype was significantly associated with an increase in both 20-hydroxyeicosatetraenoic acid excretion and systolic blood pressure. The CYP4A11 CC/TC genotype was significantly associated with a reduction in 20-hydroxyeicosatetraenoic acid excretion but was not associated with blood pressure. We have demonstrated for the first time in humans that polymorphisms of the CYP4F2 and CYP4A11 genes have opposite effects on 20-hydroxyeicosatetraenoic acid excretion. The positive association between the CYP4F2 GA/AA genotype and both systolic blood pressure and 20-hydroxyeicosatetraenoic acid excretion strengthens a role for 20-hydroxyeicosatetraenoic acid in the modulation of blood pressure.

Association between post-ischemic forearm blood flow and blood pressure response to maximal exercise in well trained healthy young men

BACKGROUND

The relationship between peripheral circulation and blood pressure (BP) response to maximal exercise is an intriguing and not yet well defined topic.

AIMS

Aims of the present study were to investigate in well trained young healthy males the possible relationships between the endothelial or the smooth muscle component of the peripheral circulation and 1) the BP response to physical exercise on treadmill 2) the body mass composition.

SUBJECTS AND METHODS

Fifteen subjects (18-36 years), regularly performing physical activity 3 times weekly underwent the following examinations: body composition by bioelectrical impedance analysis; measurement of the forearm blood flow (FBF) at rest and during post-ischemic hyperemia by strain-gauge plethysmography at the upper arm; measurement of brachial artery diameter (BAD) at rest and after 4-min ischemia by echography; BP response to maximal exercise on treadmill with the determination of maximal oxygen consumption and the measurement of lactic acid serum concentration.

RESULTS

BAD was significantly increased during post-ischemic hyperemia up to the 4th minute of observation with a peak at 60 s (+8.5%); FBF increased at 30 s after ischemia (+210%) and returned to baseline levels at the 2nd minute. In the linear correlation analysis, systolic BP increase at the end of the maximal exercise was significantly and inversely related to the increase in FBF (r=-0.663, p<0.01) and to the early FMD (r=0.503, p<0.05). In the multiple regression analysis, however, only FBF independently affected SBP increase during exercise (t=-3.268, p<0.02). Systolic BP increase at the end of the maximal exercise was significantly related to the increase in FBF but not to that of BAD. Among parameters of body composition, fat-free mass was closely related to changes only in BAD.

CONCLUSIONS

These data indicate that FBF, which depends on the smooth muscle component of the peripheral circulation, is closely related to BP response to exercise while the endothelial function, which has been determined as changes in BAD, is related to the fat-free mass of the body, possibly through the peripheral insulin sensitivity.

Systolic and diastolic hypertension impair endothelial vasodilatory function in different types of vessels in the elderly: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

BACKGROUND

Endothelium-dependent vasodilation (EDV) is known to be impaired in middle-aged hypertensive individuals, but less is known regarding hypertension in the elderly.

OBJECTIVE

In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, different techniques to evaluate EDV in resistance and conduit arteries were applied in elderly subjects and were related to the type of hypertension.

DESIGN AND METHODS

In this population-based study, 1016 subjects aged 70 years were evaluated by the invasive forearm technique with acetylcholine (EDV), brachial artery ultrasound to assess flow-mediated dilatation (FMD) and pulse wave analysis with a beta-2 receptor agonist challenge, terbutaline. Those without antihypertensive treatment were divided into three groups: normotensive individuals (n = 256), and those with isolated systolic hypertension (n = 309) or combined systolic/diastolic hypertension (n = 79).

RESULTS

Compared with normotensive individuals, EDV was reduced in those with combined systolic/diastolic hypertension only (P = 0.0019), whereas FMD was mainly reduced in those with isolated systolic hypertension (P = 0.013). Furthermore, in regression analysis, EDV was related to diastolic blood pressure only (r = -0.10, P = 0.017), whereas FMD was mainly related to systolic blood pressure (r = -0.13, P = 0.0023). The pulse wave-based method to analyse vasoreactivity was not consistently affected by hypertension.

CONCLUSIONS

In elderly subjects, systolic hypertension mainly impairs conduit artery endothelial vasodilatory function, whereas diastolic hypertension mainly induces dysfunction in resistance arteries.

Vascular structure and function in women: relationship with body mass index

BACKGROUND

The purpose of the present study was to compare endothelial function in lean (body mass index [BMI]=18.0-24.9 kg/m2); overweight (BMI=25-29.9 kg/m2); and obese (BMI>30 kg/m2), healthy, eumenorrheic women.

METHODS

Eighteen lean, 22 overweight, and 19 obese eumenorrheic middle-aged women were studied. Vascular structure and function were assessed via non-invasive ultrasound imaging of the carotid and brachial arteries. Body composition, blood pressure, fasting blood lipids, glucose, and insulin also were measured.

RESULTS

The groups demonstrated significantly (p<0.001) different mean values for total body, lean body, and fat masses. The obese group demonstrated significantly (p<0.05) elevated fasting glucose and insulin levels and lower high-density lipoprotein levels as compared to the lean group. The overweight group also demonstrated elevated fasting glucose levels as compared to the lean group (p<0.05) with no significant difference from the obese group. Only systolic blood pressure differed among the three groups, being elevated in the obese group compared to the lean group (p<0.05). The obese group demonstrated significantly (p<0.05) elevated carotid artery lumen diameter, carotid artery wall cross-sectional area, and brachial artery lumen diameter with significantly (p<0.05) lower flow-mediated dilation as compared to the lean group. The overweight group demonstrated elevated carotid artery wall cross-sectional area and brachial artery lumen diameter as well as lower flow-mediated dilation as compared to the lean group (p<0.05).

CONCLUSIONS

The results of this study support the hypothesis that carotid artery wall cross-sectional area is elevated and flow-mediated dilation reduced in overweight and obese eumennorheic women as compared to lean counterparts in relation to BMI classification.

Decreased heparin cofactor II activity is associated with impaired endothelial function determined by brachial ultrasonography and predicts cardiovascular events

BACKGROUND

Heparin cofactor II (HCII) could inactivate thrombin after binding to dermatan sulfate at injured arterial walls, and has been shown to be a novel and independent antiatherosclerotic factor. However, the relation between plasma HCII activity and peripheral vascular endothelial function remains unclear.

METHODS

A total of 199 patients (mean age, 63+/-14 years) were enrolled and followed up for a median period of 24 months. Endothelial function was assessed using brachial ultrasonography to determine endothelium dependent flow-mediated vasodilation (FMD). Cox regression analyses were conducted for the 199 subjects, with cardiovascular events being defined as myocardial infarction (MI), percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), ischemic stroke, and peripheral artery revascularization.

RESULTS

A total of 31 patients (16%) had cardiovascular events. Patients with cardiovascular events had significantly lower HCII activity (112+/-34 versus 127+/-34%, p=0.027) and lower antithrombin III (ATIII) activity (82+/-12 versus 88+/-13%, p=0.014) than those without events. By multivariate analysis, age (p=0.012), hsCRP (p=0.020) and HCII activity (p=0.035) were correlated with FMD. Kaplan-Meier analysis was performed and showed plasma HCII (p=0.036) and ATIII activities (p=0.005) were predictors of cardiovascular events. By Cox regression analysis, plasma HCII activity (p=0.026) could be an independent predictor of future cardiovascular events, but not ATIII.

CONCLUSIONS

The present study demonstrates that plasma HCII activity is positively correlated with endothelial vasodilator function. Furthermore, plasma HCII activity could be a predictor of future cardiovascular events in patients with suspected coronary artery disease, suggesting its role in atherosclerosis.

Partial substitution of carbohydrate intake with protein intake from lean red meat lowers blood pressure in hypertensive persons

BACKGROUND

Compared with carbohydrate intake, dietary intake of plant protein can lower blood pressure in humans, but the effects of animal protein intake on blood pressure have yet to be investigated.

OBJECTIVE

We aimed to determine whether partial substitution of carbohydrate intake with animal protein intake from lean red meat changes blood pressure and other markers of cardiovascular disease risk in hypertensive persons.

DESIGN

Hypertensive persons (n = 60) were recruited to an 8-wk parallel-design study. The participants were randomly assigned either to maintain their usual diet (control group) or to partially replace energy intake from carbohydrate-rich foods with protein from lean red meat (protein group). Measurements were performed at baseline and at the end of the intervention.

RESULTS

Compared with the control group, the protein group had a significantly higher protein intake [x (95% CI) percent of energy: 5.3% (3.7%, 6.9%), P < 0.001] and a corresponding lower carbohydrate intake [-5.3% of energy (-7.9%, -2.7%), P < 0.001]. Body weight and intakes of fat, alcohol, and fiber were not significantly different between the groups. Compared with the control group, the clinic, 24-h, awake, and asleep systolic blood pressures were lower [-5.2 (-10.3, -0.1), -4.0 (-7.4, -0.6), -4.7 (-8.9, -0.5), and -4.7 (-10.3, -0.1) mm Hg, respectively, P < 0.05] and fasting plasma glucose concentrations were higher [0.33 mmol/L (0.09, 0.58 mmol/L), P = 0.008] in the protein group. These differences were independent of age, sex, and changes in weight, alcohol intake, or urinary sodium and potassium excretion. Diastolic blood pressure and heart rate, arterial compliance, blood lipids, and serum insulin were not significantly different between the groups.

CONCLUSION

Within the context of other studies, these results suggest that modest substitution of carbohydrate-rich foods with protein-rich foods may lower blood pressure in hypertensive persons.

Endothelial dysfunction: its role in hypertensive coronary disease

PURPOSE OF REVIEW

Coronary artery disease is the major cause of death worldwide. Hypertension is a major risk factor for developing coronary disease. It is now recognized that endothelial dysfunction is an early marker of coronary artery disease before structural changes to the vessel wall are apparent on angiography or intravascular ultrasound and that it has a prognostic value in predicting cardiovascular events in hypertensive patients. This review addresses recent developments in hypertension-induced endothelial dysfunction.

RECENT FINDINGS

Hyperaldosteronism causes endothelial dysfunction independent of high blood pressure. Exaggerated exercise blood pressure response has been related to endothelial dysfunction. Cyclosporin-A-induced endothelial dysfunction is related to reduced cholesterol content in caveolae. Chronic kidney disease induces changes in caveoli-1 and thus contributes to the reduced nitric oxide bioavailability, and causes oxidative stress independent of the high blood pressure. Asymmetric dimethylarginine plays a role in endothelial dysfunction in hypertensive patients independent of insulin resistance. 20-Hydroxyeicosatetraenoic acid is an independent predictor of hypertension in postmenopausal women. Endothelial dysfunction precedes and predicts the development of hypertension in postmenopausal women. Oral treatment with L-arginine improves endothelial dysfunction in hypertensives and lowers the blood pressure.

SUMMARY

The pathophysiology of endothelial dysfunction in hypertension is multifactorial. Recent findings have contributed to our understanding of mechanisms of endothelial dysfunction and support a role for early intervention to prevent irreversible vascular and organ damage.

Urinary 20-hydroxyeicosatetraenoic acid excretion is associated with oxidative stress in hypertensive subjects

Oxidative stress has been implicated in the pathogenesis of hypertension. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a cytochrome P450 product of arachidonic acid metabolism, thought to be involved in the regulation of blood pressure (BP). The metabolism of arachidonic acid by cytochrome P450 enzymes may be a significant source of oxidative stress. F2-isoprostanes are reliable markers of in vivo oxidative damage. gamma-Glutamyl transpeptidase (gamma-GT) has traditionally been associated with alcohol intake or liver dysfunction and may be an early marker of oxidative stress. The objective of the present study was to investigate relationships between 20-HETE excretion and markers of oxidative stress (F2-isoprostanes and gamma-GT). Sixty-nine treated hypertensive subjects underwent measurement of 24-h ambulatory BP, serum gamma-GT, and urinary F2-isoprostane and 20-HETE excretion. 20-HETE excretion was positively associated with 24-h diastolic BP (p = 0.005), alcohol intake (p = 0.008), gamma-GT (p = 0.007), and F2-isoprostanes (p = 0.005). F2-isoprostanes were positively associated with alcohol intake (p = 0.018) and gamma-GT (p = 0.01). In a multivariate regression, gamma-GT remained an independent predictor of 20-HETE excretion, after adjustment for age, gender, BMI, and alcohol intake. In conclusion, the study highlights the positive association observed between 20-HETE excretion and markers of oxidative damage. The study also provides evidence that gamma-GT may be a useful marker of oxidative stress.