Omega-3 fatty acids and endothelial function: A GRADE-assessed systematic review and meta-analysis.

INTRODUCTION: N-3 polyunsaturated fatty acids (PUFAs) supplementation has been reported to have an impact on flow-mediated dilatation (FMD), a conventionally used clinical technique for estimating endothelial dysfunction. However, its proven effects on endothelial function are unclear. This systematic review and meta-analysis were conducted to evaluate the effects of n-3 PUFAs supplementation on FMD of the brachial artery. METHOD: This study was performed following the PRISMA guidelines. To identify eligible RCTs, a systematic search was completed in PubMed/Medline, Scopus and Web of Science using relevant keywords. A fixed- or random-effects model was utilized to estimate the weighted mean difference (WMD) and 95% confidence interval (95% CI). RESULTS: Thirty-two studies (with 35 arms) were included in this meta-analysis, involving 2385 subjects with intervention duration ranging from 4 to 48 weeks. The pooled meta-analysis demonstrated a significant effect of omega-3 on FMD (WMD = 0.8%, 95% CI = 0.3-1.3, p = .001) and heterogeneity was significant (I2 = 82.5%, p < .001). CONCLUSION: We found that n-3 PUFA supplementation improves endothelial function as estimated by flow-mediated dilatation of the brachial artery.

Brachial and carotid hemodynamic response to hot water immersion in men and women.

This study sought to compare the brachial and carotid hemodynamic response to hot water immersion (HWI) between healthy young men and women. Ten women (W) and 11 men (M) (24 ± 4 yr) completed a 60-min HWI session immersed to the level of the sternum in 40°C water. Brachial and carotid artery hemodynamics (Doppler ultrasound) were measured at baseline (seated rest) and every 15 min throughout HWI. Within the brachial artery, total shear rate was elevated to a greater extent in women [+479 (+364, +594) s-1] than in men [+292 (+222, +361) s-1] during HWI (P = 0.005). As shear rate is inversely proportional to blood vessel diameter and directly proportional to blood flow velocity, the sex difference in brachial shear response to HWI was the result of a smaller brachial diameter among women at baseline (P < 0.0001) and throughout HWI (main effect of sex, P < 0.0001) and a greater increase in brachial velocity seen in women [+48 (+36, +61) cm/s] compared with men [+35 (+27, +43) cm/s] with HWI (P = 0.047) which allowed for a similar increase in brachial blood flow between sexes [M: +369 (+287, +451) mL/min, W: +364 (+243, +486) mL/min, P = 0.943]. In contrast, no differences were seen between sexes in carotid total shear rate, flow, velocity, or diameter at baseline or throughout HWI. These data indicate the presence of an artery-specific sex difference in the hemodynamic response to a single bout of HWI.

Inorganic nitrate supplementation attenuates conduit artery retrograde and oscillatory shear in older adults.

Aging causes deleterious changes in resting conduit artery shear patterns and reduced blood flow during exercise partially attributable to reduced nitric oxide (NO). Inorganic nitrate increases circulating NO bioavailability and may, therefore, improve age-associated changes in shear rate as well as exercise hyperemia. Ten older adults (age: 67 ± 3 yr) consumed 4.03 mmol nitrate and 0.29 mmol nitrite (active) or devoid of both (placebo) daily for 4 wk in a randomized, double-blinded, crossover fashion. Brachial artery diameter (D) and blood velocity (Vmean) were measured via Doppler ultrasound at rest for the characterization of shear profile as well as during two handgrip exercise trials (4 and 8 kg) for calculation of forearm blood flow (Vmean × cross-sectional area, FBF) and conductance [FBF/mean arterial pressure, forearm vascular conductance (FVC)]. Plasma [nitrate] and [nitrite] increased following active (P < 0.05 for both) but not placebo (P = 0.68 and 0.40, respectively) supplementation. Neither mean nor antegrade shear rate changed following either supplement (beverage-by-time P = 0.14 and 0.21, respectively). Retrograde (-13.4 ± 7.0 to -9.7 ± 6.8·s-1) and oscillatory (0.20 ± 0.08 to 0.15 ± 0.09 A.U., P < 0.05 for both) shear decreased following active, but not placebo (P = 0.81 and 0.70, respectively), supplementation. The FBF response (Δ from rest) to neither 4-kg nor 8-kg trials changed following either supplement (beverage-by-time P = 0.53 and 0.11, respectively). Similarly, no changes were observed in FVC responses to 4-kg or 8-kg trials (beverage-by-time P = 0.23 and 0.07, respectively). These data indicate that inorganic nitrate supplementation improves conduit artery shear profiles, but not exercise hyperemia, in older adults.NEW & NOTEWORTHY We report for the first time, to our knowledge, that 4 wk of inorganic nitrate supplementation attenuates retrograde and oscillatory shear in the brachial artery of older adults. However, this was not associated with greater hyperemic or vasodilatory responses to exercise. In sum, these data highlight favorable changes in shear patterns with aging, which may reduce the risk of atherosclerotic cardiovascular disease.

Acute Vascular Benefits of Finnish Sauna Bathing in Patients With Stable Coronary Artery Disease.

BACKGROUND: Finnish sauna bathing habits are associated with a decreased risk of cardiovascular mortality. The physiologic adaptations mediating this association remain to be fully elucidated. This study tested the hypothesis that Finnish sauna bathing acutely improves peripheral flow-mediated dilation (FMD) in middle-aged and older adults with stable coronary artery disease (CAD). METHODS: Twenty-two adults (20 male, 2 female; 67 ± 10 years) with stable CAD underwent 2 periods of 10 minutes in a Finnish sauna (81.3 ± 2.7°C, 23 ± 3% humidity) separated by 10 minutes of thermoneutral rest. Before and 51 ± 8 minutes after sauna bathing, brachial artery FMD and postocclusive reactive hyperemia (PORH) were evaluated by means of Doppler ultrasound. RESULTS: Sauna bathing increased core temperature (mean +0.66°C [95% CI 0.54-0.77], P < 0.01) and heart rate (+27 beats/min [24-29], P < 0.01), and decreased systolic (-19 mm Hg [-31 to -6]; P < 0.01) and diastolic (-6 mm Hg [-11 to -1], P < 0.01) blood pressures. Brachial artery FMD was greater after sauna bathing (+1.21% [0.16-2.26], P = 0.04), whereas PORH was unchanged (peak: +0.51 mL/min/mm Hg [-0.13 to 1.15], P = 0.11; area under the curve: +0.21 mL/mm Hg [-0.12 to 0.54]; P = 0.19). CONCLUSIONS: A typical Finnish sauna bathing session acutely improves peripheral FMD in middle-aged and older adults with stable CAD.

Total antioxidant status reduction conditioned by a serum selenium concentration decrease as a mechanism of the ultrasonographically measured brachial artery dilatation impairment in patients with arterial hypertension.

The objective of the study was to determine the relationship between serum concentrations of selenium (SeS) and zinc (ZnS), total antioxidant status (TAS) and endothelial function assessed by ultrasonographic method of dilatation of the brachial artery in 141 hypertensive patients. Patients with SeS < median were characterized by a statistically significantly lower flow-mediated dilation (FMD) than patients with SeS ≥ median. Patients with TAS < median were characterized by a significantly lower FMD than patients with TAS ≥ median. Older age, higher BMI, male gender, higher blood total cholesterol, ischemic heart disease, smoking and lower SeS constitute independent predictors of inferior endothelial function, expressed in lower FMD values. Smoking is an independent predictor of lower TAS, and the use of ß-blockers and higher serum selenium levels are independent predictors of higher TAS. In summary, a decrease in TAS should be considered as a mechanism of inferior endothelial function in hypertensive patients conditioned by a decrease in SeS.

Effect of acute high-phosphate intake on muscle metaboreflex activation and vascular function.

Increased consumption of inorganic phosphate (Pi), an abundant ingredient in processed foods, has been associated with elevated cardiovascular disease risk; however, studies investigating underlying mechanisms are limited. Recently, high dietary Pi was shown to exaggerate the pressor response to static muscle contraction in rodents in part because of overactivation of metabolically sensitive skeletal muscle afferents. Whether acute high Pi consumption affects muscle metaboreflex activation in humans remains unknown. Furthermore, although acute high Pi consumption has been shown to impair vascular function in young healthy men, equivocal results have been reported. Therefore, we hypothesized that acute high Pi consumption augments mean arterial pressure (MAP) responses during muscle metaboreflex activation, impairs endothelial function, and increases arterial stiffness in young healthy men. Subjects performed 35% maximal voluntary contraction static handgrip (HG), followed by postexercise ischemia (PEI) to isolate muscle metaboreflex activation. Resting flow-mediated dilation (FMD) and arterial stiffness were assessed. Measures were made before (pre) and 60 min after (post) subjects consumed either a high-phosphate drink (2,000 mg phosphorus and 1,520 mg sodium) or a sodium drink (1,520 mg sodium; control). MAP responses during HG (preΔ = +23 ± 3 mmHg; postΔ = +21 ± 2 mmHg; P = 0.101) and PEI (preΔ = +21 ± 4 mmHg; postΔ = +18 ± 3 mmHg; P = 0.184) were similar before and after Pi consumption. In contrast, FMD was significantly attenuated following Pi (pre = 5.1 ± 0.5%; post = 3.5 ± 0.5%; P = 0.010), whereas arterial stiffness remained unchanged. There were no changes in any measured variable after control drink consumption. In summary, although the muscle metaboreflex remains unaffected following acute high Pi consumption in young healthy men, endothelial function is impaired. NEW & NOTEWORTHY This study was the first to investigate the influence of acute high-phosphate consumption on the pressor response during isometric handgrip and isolated muscle metaboreflex activation during postexercise ischemia in young healthy humans. We demonstrated that a single high dose of phosphate (2,000 mg) did not augment blood pressure in response to exercise or isolated muscle metaboreflex activation, but endothelial function was blunted in young healthy men.

Effects of serial phlebotomy on vascular endothelial function: Results of a prospective double-blind randomized study.

INTRODUCTION: Blood donation has been proposed as a potential therapy to reduce risk of cardiovascular disease, but the effects of phlebotomy on vascular function in human subjects have not been well characterized. AIMS: We conducted a prospective randomized double-blind study to determine the effects of serial phlebotomy on vascular endothelial function in the brachial artery. Eighty-four iron-replete, non-anemic subjects were randomly assigned to one of three study treatment groups: (a) four serial phlebotomy procedures each followed by intravenous infusion of placebo normal saline; (b) four serial phlebotomy procedures each followed by intravenous infusion to replete lost iron; and (c) four serial sham phlebotomy procedures each followed by intravenous infusion of placebo normal saline. Assigned phlebotomy procedures were conducted at 56-day intervals. We measured brachial artery reactivity (BAR, %) in response to transient oxidative stress induced by oral methionine with high-resolution duplex ultrasound imaging before and one week after the fourth study phlebotomy. RESULTS: Before phlebotomy, oral methionine decreased BAR by -2.04% (95% CI -2.58%, -1.50%), P < 0.001) with no significant difference between groups (P = 0.42). After phlebotomy, the BAR response to oral methionine did not significantly change between groups (P = 0.53). Brachial artery nitroglycerin-mediated dilation did not change in response to phlebotomy. CONCLUSIONS: Four serial phlebotomy procedures over six months with or without intravenous iron supplementation did not alter vascular endothelial function in the brachial artery when compared with sham phlebotomy.

Positive Effects of Tomato Paste on Vascular Function After a Fat Meal in Male Healthy Subjects.

Tomato consumption has been recently associated with a reduced incidence of cardiovascular disease (CVD). The aim of this study was to test whether a seven-day period of tomato paste purèe (tomato paste, TP) supplementation could improve some haemodynamic parameters in healthy volunteers before and after a standardized fat meal (FM). METHODS AND RESULTS: Nineteen healthy male volunteers participated in a randomized, single-blind (operator) crossover study. Participants maintained low fiber diets (LFD) during the study periods. They were randomized either to a LFD and TP arm (80 g of TP/day) for seven-days, or to a control arm (LFD-only) with a two-week washout period. Flow Mediated Dilatation and other morpho-functional vascular indices were measured by ultrasound. Stiffness Index and Reflection Index were estimated by digital photo-plethysmography. All these parameters were measured one h before and two and 3.5 h after the FM. The difference in Stiffness Index was increased in the LFD and TP + FM-arm, as compared to the LFD-only + FM arm at both two and 3.5 h points. After the FM, in both arms, at two h, we observed a reduction in the Reflection Index and an increase in heart rate. Interestingly, only in the LFD and TP + FM-arm, some haemodynamic changes were detectable at two h; notably, there was an increase in brachial artery diameter and a reduction in diastolic blood pressure (BP). CONCLUSIONS: TP has no effect on Flow Mediated Dilatation but acutely modifies some haemodynamic parameters triggered by FM, suggesting possible haemodynamic beneficial effects in people consuming tomatoes.

Low frequency electrical muscle stimulation and endothelial function in advanced heart failure patients.

AIM: Obtain initial estimates of the change in brachial artery endothelial function and maximal oxygen uptake (VO2peak ) with 8 weeks of low-frequency electrical muscle stimulation (LF-EMS) or sham in patients with advanced chronic heart failure. METHODS AND RESULTS: Using a double blind, randomized design, 35 patients with chronic heart failure (New York Heart Association class III-IV) were assigned to 8 weeks (5 × 60 min per week) of either LF-EMS (4 Hz, continuous) or sham (skin level stimulation only) of the quadriceps and hamstrings muscles. Four of the five sessions were at home and one under supervision. Ultrasound images of resting brachial artery diameter and post 5 min occlusion to determine flow-mediated dilation (FMD), a marker of vascular function and peak oxygen uptake (VO2peak ) during cardiopulmonary exercise test, were measured before and after LF-EMS (n = 20) and sham (n = 15) interventions. FMD improved by 2.56% (95% confidence interval: 0.69 to 3.80) with LF-EMS compared with sham (P = 0.07). There were no notable changes in VO2peak . CONCLUSIONS: Improvements in FMD with LF-EMS may have a clinically meaningful effect as higher FMD is associated with better prognosis. This is a preliminary finding, and a larger trial is warranted.

Differential influence of vitamin C on the peripheral and cerebral circulation after diving and exposure to hyperoxia.

We examined if the diving-induced vascular changes in the peripheral and cerebral circulation could be prevented by oral antioxidant supplementation. Fourteen divers performed a single scuba dive to eighteen meter sea water for 47 min. Twelve of the divers participated in a follow-up study involving breathing 60% of oxygen at ambient pressure for 47 min. Before both studies, participants ingested vitamin C (2 g/day) or a placebo capsule for 6 days. After a 2-wk washout, the study was repeated with the different condition. Endothelium-dependent vasodilator function of the brachial artery was assessed pre- and postintervention using the flow-mediated dilation (FMD) technique. Transcranial Doppler ultrasound was used to measure intracranial blood velocities pre- and 90 min postintervention. FMD was reduced by ∼32.8% and ∼21.2% postdive in the placebo and vitamin C trial and posthyperoxic condition in the placebo trial by ∼28.2% ( P < 0.05). This reduction in FMD was attenuated by ∼10% following vitamin C supplementation in the hyperoxic study ( P > 0.05). Elevations in intracranial blood velocities 30 min after surfacing from diving were reduced in the vitamin C study compared with the placebo trial ( P < 0.05). O2 breathing had no postintervention effects on intracranial velocities ( P > 0.05). Prophylactic ingestion of vitamin C effectively abrogated peripheral vascular dysfunction following exposure to 60% O2 but did not abolish the postdive decrease in FMD. Transient elevations of intracranial velocities postdive were reduced by vitamin C. These findings highlight the differential influence of vitamin C on peripheral and cerebral circulations following scuba diving, which are only partly mediated via hyperoxia.

Osteopathic manual therapy in heart failure patients: A randomized clinical trial.

BACKGROUND: Heart Failure (HF) patients usually present with increased arterial resistance and reduced blood pressure (BP) leading to an impaired functional capacity. Osteopathic Manual Therapy (OMT) focused on myofascial release techniques (MRT) and in the balancing of diaphragmatic tensions, has been shown to improve blood flow in individuals using the resistive index (RI). However, its effects in HF patients have not been examined. PURPOSE: To evaluate the acute response of selected osteopathic techniques on RI, heart rate (HR), and BP in patients with HF. METHODS: Randomized-controlled clinical trial of HF patients assigned to MRT (six different techniques with three aimed at the pelvis, two at the thorax, and one at the neck for 15 min) or Control group (subjects in supine position for 15 min without intervention). The RI of the femoral, brachial and carotid arteries was measured via doppler ultrasound while HR and BP were measured via sphygmomanometry before and after a single MRT or control intervention. RESULTS: Twenty-two HF patients equally distributed (50% male, mean age 53 years; range 32-69 years) (ejection fraction = 35.6%, VO2peak: 12.9 mL/kg-1 min-1) were evaluated. We found no intra or inter group differences in RI of the carotid (ΔMRT: 0.07% vs Δ Control:11.8%), brachial (ΔMRT:0.17% vs ΔControl: 2.9%), or femoral arteries (ΔMRT:1.65% vs ΔControl: 0.97%) (P > 0.05) and no difference in HR or BP (ΔMRT:0.6% vs ΔControl: 3%), (P > 0.05). CONCLUSION: A single MRT session did not significantly change the RI, HR, or BP of HF patients.

Treatment with omega-3 polyunsaturated fatty acids does not improve endothelial function in patients with type 2 diabetes and very high cardiovascular risk: A randomized, double-blind, placebo-controlled study (Omega-FMD).

BACKGROUND AND AIMS: Numerous recent studies conducted in different clinical settings have focused on the benefits of omega-3 polyunsaturated fatty acids (n-3 PUFAs) in the prevention of cardiovascular diseases. There is limited evidence that patients with type 2 diabetes (T2D) and very high cardiovascular risk can also benefit from a high dose of n-3PUFAs, especially those on optimal medical therapy as recommended by the guidelines. The aim of the present study was to assess the impact of high-dose n-3 PUFA treatment on endothelial function in patients with T2D and established atherosclerotic cardiovascular disease (ASCVD). METHODS: We conducted a prospective randomized double-blind, placebo-controlled, 2-center study, in which endothelial function was measured using flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD). Serum fatty acids composition was measured by gas chromatography. All measurements were done at baseline and after 3 months of treatment with PUFAs at a dose of 2 g/d (n = 36) or placebo (n = 38). RESULTS: The majority of the study population was treated with optimal medical therapy. Despite significantly higher concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid in the n-3 PUFA group after 3-month treatment, we did not observe significant changes in endothelial function indices (FMD and NMD). However, in regression analysis, only baseline FMD was associated with EPA concentration before 3 months of n-3 PUFA treatment. CONCLUSIONS: Three months of high-dose n-3 PUFA treatment in very high-risk patients with ASCVD and T2D did not improve the endothelial function indices.

Effects of Intradialytic Neuromuscular Electrical Stimulation on Strength and Muscle Architecture in Patients With Chronic Kidney Failure: Randomized Clinical Trial.

This study aimed to evaluate the effects of neuromuscular electrical stimulation (NMES) on muscle strength and architecture, functional capacity, and endothelial function in patients with chronic kidney failure (CKF) on hemodialysis (HD). Twenty-one patients with CKF on HD were randomized into a control group (CG; n = 10) and neuromuscular electrical stimulation group (NMESG; n = 11) who received NMES in the quadriceps muscle for 8 weeks, 3 times/week (20-34 min) during HD sessions. The muscle strength of the lower limbs was evaluated by dynamometry and sit-and-stand test (SST); muscle architecture through ultrasonography; functional capacity by the distance covered in a 6-min walk test and the endothelial function by flow-mediated dilatation technique of the brachial artery. There was an increase in the strength of the lower limbs in the NMESG compared to the CG (dynamometry: 43.28 ± 16.94 vs. 35.84 ± 16.89, P = 0.006; SST: 16.10 ± 6.51 vs. 12.50 ± 4.7, P = 0.029). There was a significant reduction in pennation angles of the right vastus lateralis (RVL) and left vastus lateralis (LVL) in the CG when compared to the NMESG (RVL: 11.93 [10.70-15.11] vs. 13.57 [11.81-15.96], P = 0.039; LVL: 11.62 [9.00-14.20] vs. 15.52 [12.86-20.02], P = 0.042). There was no change in functional capacity and in the endothelial function for CG and NMESG, respectively. In conclusion, NMES increases muscle strength and has a protective effect against muscle atrophy of the lower limbs of patients with chronic kidney failure on HD.

Correlation Between Upper Limb Volume and Arterial and Venous Blood Flow Velocity in Lymphedema Secondary to Breast Cancer Treatment.

OBJECTIVE: The purpose of this study was to correlate upper limb volume and arterial and venous blood flow velocity in breast cancer survivors. METHODS: A cross-sectional study was conducted on 30 women with lymphedema and a mean age of 55.60 years (standard deviation = 8.12). For the assessment of upper limb volume, perimetry was performed with measures at 6 points on the limb, which were mathematically calculated as volume. The blood flow velocity of the axillary and brachial arteries and veins were assessed by Doppler ultrasound with a probe at 4 MHz. In the statistical analysis, a Shapiro-Wilk test determined a non-normal data distribution. Spearman correlation coefficients (ρ) were calculated to determine the association between the variables blood flow velocity and lymphedema volume. RESULTS: We identified significant and positive associations between all variables correlated with limb volume: blood flow velocity of the axillary artery (ρ = 0.381, P = .041), axillary vein (ρ = 0.383, P = .039), brachial artery (ρ = 0.375, P = .044), and the brachial vein (ρ = 0.373, P = .045). CONCLUSION: There is a positive association between limb volume and blood flow velocity in the upper limbs of women with lymphedema secondary to breast cancer treatment.

Effect of Vitamin D on Endothelial Function: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: In nonhypertensive individuals, lower levels of 25-hydroxyvitamin D (25[OH]D) have been associated with an increased risk of hypertension, and vitamin D deficiency has been associated with endothelial dysfunction in such individuals. However, the effect of vitamin D supplementation on endothelial dysfunction in nonhypertensive individuals has not been examined in a rigorous fashion. METHODS: In this randomized, double-blind, placebo-controlled trial of nonhypertensive, nondiabetic overweight, or obese individuals with vitamin D deficiency (body mass index ≥25 and 25[OH]D ≤ 20 ng/ml), we assigned subjects to receive either ergocalciferol (50,000 units) or matching placebo, once a week for 8 weeks. Our primary outcome was endothelial-dependent vasodilation (EDV) measured by brachial artery ultrasound at baseline and 8 weeks postrandomization. RESULTS: By the end of the trial, 46 and 47 participants were allocated to receive ergocalciferol and placebo, respectively. Mean 25(OH)D levels increased from 14.9 to 30.3 in the vitamin D group and 14.4 to 17.4 in the placebo. EDV did not change significantly with either vitamin D repletion (from 6.3 ± 3.6% at baseline to 6.1 ± 4.6% at 8 weeks; P value = 0.78) or placebo (7.9 ± 4.7% to 6.8 ± 4.7%; P = 0.17). The treatment effect P value (comparing the 8-week change with ergocalciferol to the change with placebo) was 0.35. CONCLUSIONS: In this randomized, double-blind, placebo-controlled trial, there was no improvement in endothelial function (measured as EDV) after repletion of vitamin D in overweight/obese nonhypertensive individuals.

Ebselen does not improve oxidative stress and vascular function in patients with diabetes: a randomized, crossover trial.

Oxidative stress is a key driver of vascular dysfunction in diabetes mellitus. Ebselen is a glutathione peroxidase mimetic. A single-site, randomized, double-masked, placebo-controlled, crossover trial was carried out in 26 patients with type 1 or type 2 diabetes to evaluate effects of high-dose ebselen (150 mg po twice daily) administration on oxidative stress and endothelium-dependent vasodilation. Treatment periods were in random order of 4 wk duration, with a 4-wk washout between treatments. Measures of oxidative stress included nitrotyrosine, plasma 8-isoprostanes, and the ratio of reduced to oxidized glutathione. Vascular ultrasound of the brachial artery and plethysmographic measurement of blood flow were used to assess flow-mediated and methacholine-induced endothelium-dependent vasodilation of conduit and resistance vessels, respectively. Ebselen administration did not affect parameters of oxidative stress or conduit artery or forearm arteriolar vascular function compared with placebo treatment. There was no difference in outcome by diabetes type. Ebselen, at the dose and duration evaluated, does not improve the oxidative stress profile, nor does it affect endothelium-dependent vasodilation in patients with diabetes mellitus.

Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans.

KEY POINTS: A recent 30 year prospective study showed that lifelong sauna use reduces cardiovascular-related and all-cause mortality; however, the specific cardiovascular adaptations that cause this chronic protection are currently unknown. We investigated the effects of 8 weeks of repeated hot water immersion ('heat therapy') on various biomarkers of cardiovascular health in young, sedentary humans. We showed that, relative to a sham group which participated in thermoneutral water immersion, heat therapy increased flow-mediated dilatation, reduced arterial stiffness, reduced mean arterial and diastolic blood pressure, and reduced carotid intima media thickness, with changes all on par or greater than what is typically observed in sedentary subjects with exercise training. Our results show for the first time that heat therapy has widespread and robust effects on vascular function, and as such, could be a viable treatment option for improving cardiovascular health in a variety of patient populations, particularly those with limited exercise tolerance and/or capabilities. ABSTRACT: The majority of cardiovascular diseases are characterized by disorders of the arteries, predominantly caused by endothelial dysfunction and arterial stiffening. Intermittent hot water immersion ('heat therapy') results in elevations in core temperature and changes in cardiovascular haemodynamics, such as cardiac output and vascular shear stress, that are similar to exercise, and thus may provide an alternative means of improving health which could be utilized by patients with low exercise tolerance and/or capabilities. We sought to comprehensively assess the effects of 8 weeks of heat therapy on biomarkers of vascular function in young, sedentary subjects. Twenty young, sedentary subjects were assigned to participate in 8 weeks (4-5 times per week) of heat therapy (n = 10; immersion in a 40.5°C bath sufficient to maintain rectal temperature ≥ 38.5°C for 60 min per session) or thermoneutral water immersion (n = 10; sham). Eight weeks of heat therapy increased flow-mediated dilatation from 5.6 ± 0.3 to 10.9 ± 1.0% (P < 0.01) and superficial femoral dynamic arterial compliance from 0.06 ± 0.01 to 0.09 ±0.01 mm(2)  mmHg(-1) (P = 0.03), and reduced (i.e. improved) aortic pulse wave velocity from 7.1 ± 0.3 to 6.1 ± 0.3 m s(-1) (P = 0.03), carotid intima media thickness from 0.43 ± 0.01 to 0.37 ± 0.01 mm (P < 0.001), and mean arterial blood pressure from 83 ± 1 to 78 ± 2 mmHg (P = 0.02). No changes were observed in the sham group or for carotid arterial compliance, superficial femoral intima media thickness or endothelium-independent dilatation. Heat therapy improved endothelium-dependent dilatation, arterial stiffness, intima media thickness and blood pressure, indicating improved cardiovascular health. These data suggest heat therapy may provide a simple and effective tool for improving cardiovascular health in various populations.

Acute supplementation of N-acetylcysteine does not affect muscle blood flow and oxygenation characteristics during handgrip exercise.

N-acetylcysteine (NAC; antioxidant and thiol donor) supplementation has improved exercise performance and delayed fatigue, but the underlying mechanisms are unknown. One possibility isNACsupplementation increases limb blood flow during severe-intensity exercise. The purpose was to determine ifNACsupplementation affected exercising arm blood flow and muscle oxygenation characteristics. We hypothesized thatNACwould lead to higher limb blood flow and lower muscle deoxygenation characteristics during severe-intensity exercise. Eight healthy nonendurance trained men (21.8 ± 1.2 years) were recruited and completed two constant power handgrip exercise tests at 80% peak power until exhaustion. Subjects orally consumed either placebo (PLA) orNAC(70 mg/kg) 60 min prior to handgrip exercise. Immediately prior to exercise, venous blood samples were collected for determination of plasma redox balance. Brachial artery blood flow (BABF) was measured via Doppler ultrasound and flexor digitorum superficialis oxygenation characteristics were measured via near-infrared spectroscopy. FollowingNACsupplementaiton, plasma cysteine (NAC: 47.2 ± 20.3 µmol/L vs.PLA: 9.6 ± 1.2 µmol/L;P = 0.001) and total cysteine (NAC: 156.2 ± 33.9 µmol/L vs.PLA: 132.2 ± 16.3 µmol/L;P = 0.048) increased. Time to exhaustion was not significantly different (P = 0.55) betweenNAC(473.0 ± 62.1 sec) andPLA(438.7 ± 58.1 sec). RestingBABFwas not different (P = 0.79) withNAC(99.3 ± 31.1 mL/min) andPLA(108.3 ± 46.0 mL/min).BABFwas not different (P = 0.42) during exercise or at end-exercise (NAC: 413 ± 109 mL/min;PLA: 445 ± 147 mL/min). Deoxy-[hemoglobin+myoglobin] and total-[hemoglobin+myoglobin] were not significantly different (P = 0.73 andP = 0.54, respectively) at rest or during exercise between conditions. We conclude that acuteNACsupplementation does not alter oxygen delivery during exercise in men.

Endothelial function and insulin sensitivity during acute non-esterified fatty acid elevation: Effects of fat composition and gender.

BACKGROUND AND AIMS: We have reported that adverse effects on flow-mediated dilation of an acute elevation of non-esterified fatty acids rich in saturated fat (SFA) are reversed following addition of long-chain (LC) n-3 polyunsaturated fatty acids (PUFA), and hypothesised that these effects may be mediated through alterations in insulin signalling pathways. In a subgroup, we explored the effects of raised NEFA enriched with SFA, with or without LC n-3 PUFA, on whole body insulin sensitivity (SI) and responsiveness of the endothelium to insulin infusion. METHODS AND RESULTS: Thirty adults (mean age 27.8 y, BMI 23.2 kg/m(2)) consumed oral fat loads on separate occasions with continuous heparin infusion to elevate NEFA between 60 and 390 min. For the final 150 min, a hyperinsulinaemic-euglycaemic clamp was performed, whilst FMD and circulating markers of endothelial function were measured at baseline, pre-clamp (240 min) and post-clamp (390 min). NEFA elevation during the SFA-rich drinks was associated with impaired FMD (P = 0.027) whilst SFA + LC n-3 PUFA improved FMD at 240 min (P = 0.003). In males, insulin infusion attenuated the increase in FMD with SFA + LC n-3 PUFA (P = 0.049), with SI 10% greater with SFA + LC n-3 PUFA than SFA (P = 0.041). CONCLUSION: This study provides evidence that NEFA composition during acute elevation influences both FMD and SI, with some indication of a difference by gender. However our findings are not consistent with the hypothesis that the effects of fatty acids on endothelial function and SI operate through a common pathway. This trial was registered at clinical trials.gov as NCT01351324 on 6th May 2011.

Effects of Pycnogenol® on endothelial dysfunction in borderline hypertensive, hyperlipidemic, and hyperglycemic individuals: the borderline study.

AIM: This registry study aimed to evaluate the effects of supplementation with pycnogenol on altered endothelial function (EF) in borderline hypertensive, hyperlipidemic and hyperglycemic subjects without atherosclerotic changes in their main arteries and no coronary artery disease. METHODS: Flow mediated dilatation (FMD) and endothelium-independent (EID) dilatation were measured with brachial ultrasound after occlusion. Also, after occlusion, laser Doppler (LDF) flux and distal straingauge flow were measured. Oxidative stress (oxstress) was evaluated at 8 and 12 weeks. 93 subjects with borderline symptoms were enrolled into the study: 32 hypertensives, 31 hyperlipidemics, 30 hyperglycemics. All participants were instructed to follow the best available management to control their symptoms. In addition to best management, half of the subjects in each group used 150 mg/day Pycnogenol(®). 31 normal subjects were included as control. RESULTS: After 12 weeks metabolic values and blood pressure were back to normal in all subjects. Values were slightly better under Pycnogenol(®). FMD increased after 8 weeks from an average 5.3;3.4% to 8.2;2.2% with a further increase to 8.8;3.1% (P<0.05) at 12 weeks. No effects were found in controls and normal subjects. EID of normal subjects was consistently higher with 26%. LDF skin flux increased with Pycnogenol(®) at 8 weeks and 12 weeks. The final flux increase was not different from normal values. In controls flux after occlusion was not improved at 8 weeks; there was a significant but minor increase at 12 weeks. Flux increases were superior in all Pycnogenol(®) subjects. In Pycnogenol(®) subjects, limb flow after occlusion increased at 8 weeks with a further increase at 12 weeks. In controls inclusion flow after occlusion was comparable at 8 and 12 weeks. Oxidative stress was significantly decreased in Pycnogenol(®) subjects at 8 and 12 weeks. Minor differences were observed in controls. CONCLUSION: This open registry study indicates that Pycnogenol(®) improves EF in preclinical, borderline subjects in a macro-microcirculatory model. This observation may suggest an important preventive possibility for borderline hypertensive, hyperglycemic and hyperlipidemic subjects.