Independent Vasodilator Responses Research Articles

Comparison effect of high-intensity interval training and moderate intensity continuous training on vascular function in a mouse model of lower extremity peripheral artery disease

Introduction
 Lower extremity peripheral artery disease (PAD), due to narrowing of the arteries supplying the legs, represents a major cause of physical disability. Exercise training is an important part of PAD treatment, improving functional capacity. Recent research suggests that exercise training-induced endothelial function improvement is involved in the benefits of exercise in PAD (Lee et al., 2023); however, the underlying molecular mechanisms remain unknown. In addition, the potential vascular benefits of high intensity training in PAD remain unexplored. Therefore, the aim of the study was to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on endurance capacity, vascular endothelial function and expression of genes related to nitric oxide (NO) bioavailability in a mouse model of PAD.
 Methods
 PAD disease model was generated in male C57BL/6 mice by ligation of the right iliac artery. Mice with PAD were divided into 3 groups: sedentary control group (SED), MICT (40 min running at 70% of maximal aerobic speed) and HIIT (8 intervals of 2.5 minutes running at 90% of maximal aerobic speed combined with 2.5 minutes of running at 50% of maximal aerobic speed). Mice were exercised three times per week for 8 weeks. Maximal running time was determined by an incremental test until exhaustion. Vascular reactivity was assessed by measuring vasoconstrictor responses to phenylephrine as well as endothelium-dependent and -independent vasodilator responses to acetylcholine and DEA-NONOate, respectively, in isolated aortic rings. Gene expression of antioxidant enzymes (catalase and superoxide dismutase isoforms), prooxidant NADPH oxidase subunits (p22phox and p47phox), enzyme involved in NO production (endothelial NO synthase), vascular smooth muscle cell relaxation (soluble guanylate cyclase) and receptors involved in vascular tone regulation (a1 and b2 adrenergic receptors) was determined in aortic tissue by qPCR.
 Results
 Maximal running time was improved in both MICT and HIIT as compared to SED at the end of the study, but with no significant difference between the two exercise groups. Phenylephrine-induced vasoconstriction as well as vasodilator responses to acetylcholine and DEA-NONOate were significantly improved in MICT compared to SED while no significant differences were reported between HIIT and SED. There was no significant difference in gene expression among the three groups.
 Discussion/Conclusion
 MICT and HIIT were equally effective at improving endurance capacity in mice with PAD. However, only MICT improved vascular reactivity.
 References
 Lee, J., Zarezadehmehrizi, A., LaVoy, E., Markofski, M., & Park, Y. (2023). Exercise training improves brachial artery endothelial function, but does not alter inflammatory biomarkers in patients with peripheral artery disease: A systematic review and meta-analysis. Journal of Cardiovascular Translational Research. Advance online publication. https://doi.org/10.1007/s12265-023-10451-0

Effects of Aging and Exercise Training on Vasomotor Function of Bone Resistance Arteries and Bone Blood Flow

Adequate skeletal perfusion is necessary to maintain bone remodeling processes, and decrements in bone arterial function and regional blood flow may lead to conditions such as osteoporosis. Aging elicits progressive bone loss, associated with impaired bone vasomotor function and perfusion, that can lead to osteoporosis. Although these age‐related adaptations are ameliorated via exercise training, the specific mechanisms underlying exercise‐induced alterations of bone vasomotor function with aging remain largely unknown. The purpose of this study was to elucidate the age‐ and exercise‐induced vasomotor adaptations of the bone principal nutrient artery and subsequent alterations in bone blood flow.Young and old male Fischer‐344 rats underwent treadmill exercise training (15 m/min, 15° incline, 1hr/day, 5 days/wk for 10–12 wks) or remained sedentary in cages. At the end of the experimental period, the femoral principal nutrient artery (PNA) was isolated, cannulated, and pressurized for vascular response studies. Vasoconstrictor responses of the PNA were assessed in vitro using α‐adrenergic agonist phenylephrine (PE, 10−9–10−4 M), receptor‐independent potassium chloride (KCl, 10–100 mM) and myogenic responsiveness to increasing intraluminal pressure (0 to 140 cmH2O). Endothelium‐dependent (ACh, 10−9–10−4 M) and ‐independent (Dea‐NONOate, 10−9–10−4 M) vasodilator responses were also evaluated. Additionally, regional blood flow to the femur was measured at rest and during exercise using radiolabeled microspheres.Vasomotor responses to agonists for constriction (PE, KCl) and dilation (ACh, Dea‐NONOate) decreased with aging. In contrast, myogenic responsiveness in old rats was greater compared with young rats (p<0.05). Vasoconstrictor response to KCl was greater after training in both young and old rats as compared to the sedentary rats. Exercise‐trained old rats also showed increased vasoconstrictor responses to PE and myogenic responsiveness; however, no significant difference was shown in young rats (p<0.05). Exercise training enhanced endothelium‐dependent vasodilation in both young and old rats; however, no significant exercise effect was observed in endothelium‐independent vasodilation (p<0.05). Regional femur blood flow to the proximal and distal metaphysis and epiphysis, as well as diaphyseal marrow, was lower in aged rats compared to young rats at rest. However, exercise‐trained old rats showed significantly increased regional blood flow during exercise compared with old SED rats (p<0.05).These results demonstrate vasomotor responses are impaired in the femoral PNA from aged rats; however, endurance training intervention at advancing age can reverse vasomotor deficits including vasoconstrictor and vasodilator response in bone resistance arteries and enhance regional bone and marrow blood flow. Such changes in bone and marrow perfusion could play an important role in enhancing the quality and strength of bone in old age following exercise training.Support or Funding InformationNIH grant AG055029

Egg white-derived peptides prevent cardiovascular disorders induced by mercury in rats: Role of angiotensin-converting enzyme (ACE) and NADPH oxidase

The study aimed to investigate the effects of egg white hydrolysate (EWH) on vascular disorders induced by mercury (Hg). For this, male Wistar rats were treated for 60days: Untreated (saline, i.m.); Mercury (HgCl2, i.m., 1st dose 4.6μg/kg, subsequent doses 0.07μg/kg/day); Hydrolysate (EWH, gavage, 1g/kg/day); Hydrolysate-Mercury. Systolic (SBP) and diastolic (DBP) blood pressure measurement and vascular reactivity experiments in aorta were performed. We analyzed endothelial dependent and independent vasodilator responses and vasoconstrictor response to phenylephrine (Phe) in absence and presence of endothelium, a NOS inhibitor, a NADPH oxidase inhibitor, the superoxide dismutase, a non-selective COX inhibitor, a selective COX-2 inhibitor, an AT-1 receptors blocker. In situ superoxide anion production, SOD-1, NOX-4, p22phox, COX-2 and AT-1 mRNA levels and NOX-1 protein expression were performed in aorta while the determination of angiotensin converting enzyme (ACE) activity was measured in plasma. As results, EWH prevented the increase in SBP and Phe responses and the endothelial dysfunction elicited by Hg, which was related to decreased ACE activity and NOX activation by EWH and, subsequently, alleviated ROS production and improved NO bioavailability in aorta. In conclusion, EWH could be considered as alternative or complementary treatment tools for Hg-induced cardiovascular damage.

Defining the Mechanism of Erythropoietin's Vasoactive Properties in Resistance Arteries

Clinically, erythropoietin (EPO) is known to increase systemic vascular resistance, however, in cell culture, EPO has been reported to increase activation of endothelial nitric oxide synthase (eNOS). How EPO can activate eNOS, while causing vasoconstriction, is likely due to EPO's ability to activate multiple receptors, the homodimeric EPO receptor (EPOR2) and the heterodimeric EPOR/beta common receptor (βCR). The purpose of this study was to investigate the contribution of each receptor in endothelial‐dependent vasodilation. We hypothesized that the vasoconstrictive effects seen with EPO administration are mediated through the EPOR2. To study the effects of each receptor, we utilized EPO and the EPO peptide (EPOp), which solely acts on the heterodimeric EPOR/βCR. Adult 16‐week old male C57BL/6 mice were euthanized and first order mesenteric arteries were isolated for in vitro study. Endothelium‐dependent (acetylcholine) and ‐independent (sodium nitroprusside) vasodilator responses were evaluated with and without an acute EPO (50 mIU/mL) or EPOp (25 ng/mL) pretreatment. We found that acetylcholine, endothelium‐dependent, vasodilation was impaired in arteries pretreated with both EPO and EPOp as compared to controls. However, while the EPOp vasodilation was impaired by 60%, EPO pretreatment totally inhibited acetylcholine‐induced vasodilation. Importantly EPO, EPOp and control treated arteries were all able to vasodilate equally in response to sodium nitroprusside, an endothelium‐independent vasodilator. These findings suggest that acute activation of the homodimeric EPOR2 or the heterodimeric EPOR/βCR can both lead to an endothelial specific impairment of vasodilator function in resistance arteries. We will discuss the putative mechanism of these effects along with the physiologic significance.

Effects of High-LET Radiation Exposure and Hindlimb Unloading on Skeletal Muscle Resistance Artery Vasomotor Properties and Cancellous Bone Microarchitecture in Mice.

Weightlessness during spaceflight leads to functional changes in resistance arteries and loss of cancellous bone, which may be potentiated by radiation exposure. The purpose of this study was to assess the effects of hindlimb unloading (HU) and total-body irradiation (TBI) on the vasomotor responses of skeletal muscle arteries. Male C57BL/6 mice were assigned to control, HU (13-16 days), TBI (1 Gy (56)Fe, 600 MeV, 10 cGy/min) and HU-TBI groups. Gastrocnemius muscle feed arteries were isolated for in vitro study. Endothelium-dependent (acetylcholine) and -independent (Dea-NONOate) vasodilator and vasoconstrictor (KCl, phenylephrine and myogenic) responses were evaluated. Arterial endothelial nitric oxide synthase (eNOS), superoxide dismutase-1 (SOD-1) and xanthine oxidase (XO) protein content and tibial cancellous bone microarchitecture were quantified. Endothelium-dependent and -independent vasodilator responses were impaired in all groups relative to control, and acetylcholine-induced vasodilation was lower in the HU-TBI group relative to that in the HU and TBI groups. Reductions in endothelium-dependent vasodilation correlated with a lower cancellous bone volume fraction. Nitric oxide synthase inhibition abolished all group differences in endothelium-dependent vasodilation. HU and HU-TBI resulted in decreases in eNOS protein levels, while TBI and HU-TBI produced lower SOD-1 and higher XO protein content. Vasoconstrictor responses were not altered. Reductions in NO bioavailability (eNOS), lower anti-oxidant capacity (SOD-1) and higher pro-oxidant capacity (XO) may contribute to the deficits in NOS signaling in skeletal muscle resistance arteries. These findings suggest that the combination of insults experienced in spaceflight leads to impairment of vasodilator function in resistance arteries that is mediated through deficits in NOS signaling.

Effect of diabetes on the cutaneous microcirculation of the feet in patients with intermittent claudication.

To evaluate endothelial-dependent and - independent cutaneous vasodilator responses in the feet of patients with peripheral arterial disease (PAD) with or without Type 2 diabetes. Cutaneous microvascular responses in the dorsum of both lower limbs were measured in the supine position using Laser Doppler Fluximetry combined with iontophoretic administration of endothelial-dependent (acetylcholine, Ach) and -independent (sodium nitroprusside, SNP) vasodilators in diabetic (n = 19) and non diabetic (n = 17) patients with PAD (presenting as unilateral calf intermittent claudication (IC). In patients with diabetes and IC, endothelial-dependent vasodilation was significantly impaired in the symptomatic limb [74 (57,105) vs 68 (24,81) PU, Z =-2.79, p = 0.005] compared to the asymptomatic limb. Patients without diabetes showed no impairment of vasodilation. Resting ankle-brachial pressure index did not identify the presence of abnormalities in microvascular function. The combination of diabetes and PAD is associated with a reduction in endothelial-dependent cutaneous vasodilation in the feet without an associated reduction in endothelial independent vasodilation.

Effects of hindlimb unloading and ionizing radiation on skeletal muscle resistance artery vasodilation and its relation to cancellous bone in mice.

Spaceflight has profound effects on vascular function as a result of weightlessness that may be further compounded by radiation exposure. The purpose of the present study was to assess the individual and combined effects of hindlimb unloading (HU) and radiation (Rad) on vasodilator responses in the skeletal muscle vasculature. Adult male C57BL/6J mice were randomized to one of four groups: control (Con), HU (tail suspension for 15 days), Rad (200 cGy of (137)Cs), and HU-Rad (15-day tail suspension and 200 cGy of (137)Cs). Endothelium-dependent vasodilation of gastrocnemius feed arteries was assessed in vitro using acetylcholine (ACh, 10(-9)-10(-4) M) and inhibitors of nitric oxide synthase (NOS) and cyclooxygenase (COX). Endothelium-independent vasodilation was assessed using Dea-NONOate (10(-9)-10(-4) M). Endothelium-dependent and -independent vasodilator responses were impaired relative to Con responses in all treatment groups; however, there was no further impairment from the combination of treatments (HU-Rad) relative to that in the HU and Rad groups. The NOS-mediated contribution to endothelium-dependent vasodilation was depressed with HU and Rad. This impairment in NOS signaling may have been partially compensated for by an enhancement of PGI2-mediated dilation. Changes in endothelium-dependent vasodilation were also associated with decrements in trabecular bone volume in the proximal tibia metaphysis. These data demonstrate that the simulated space environment (i.e., radiation exposure and unloading of muscle and bone) significantly impairs skeletal muscle artery vasodilation, mediated through endothelium-dependent reductions in NOS signaling and decrements in vascular smooth muscle cell responsiveness to NO.

Forearm vasodilator reactivity in healthy male carriers of the 3q22.3 rs9818870 polymorphism

BackgroundA genome wide association study has identified a robust risk locus for cardiovascular disease on 3q22.3. However, the mechanisms by which the [C]/[T] polymorphism rs9818870 increases cardiovascular risk are unknown. This forearm blood flow (FBF) study addressed the question if the genetic association with cardiovascular disease in patients is preceded by incipient vasodilator impairment in young, healthy carriers of this new risk locus on chromosome 3. Materials and methodsAfter a pre-screening of 74 subjects 17 male healthy volunteers homozygous/heterozygous for a single nucleotide polymorphism (SNP) risk allele on 3q22.3 and a control group of 17 healthy volunteers not carrying the allele were included into this case–control study. ResultsForearm vascular endothelium-dependent and -independent vasodilator responses were in the normal range in both groups, although endothelium-dependent FBF reactivity to acetylcholine was significantly higher in SNP carriers of the risk allele. ConclusionThe augmented endothelium-dependent vasodilation of the forearm resistance vasculature does not support the presence of endothelial dysfunction in young SNP carriers and indicates that other mechanisms are responsible for the strong association between coronary artery diseases and the rs9818870 polymorphism, located on 3q22.3.

Effects of hindlimb unloading and radiation on vasodilator responses in skeletal muscle arteries (1106.18)

Long‐term spaceflight leads to extensive changes to the microvasculature as a result of weightlessness, which may be compounded by the effects of radiation exposure. The purpose of this study was to assess the individual and combined effects of hindlimb unloading (HU) and radiation (Rad) on vasodilator responses in the skeletal muscle microcirculation.Adult male C57BL/6 mice were randomized to one of four groups: control, HU (tail suspension for 10‐11 days), Rad (100cGy of 150MeV protons and 20cGy of 800MeV 56Fe), and HU‐Rad. Gastrocnemius feed arteries were isolated, cannulated and pressurized for in vitro study. Endothelium‐dependent (ACh, 10‐9‐10‐4 M) and ‐independent (Dea‐NONOate, 10‐9‐10‐4 M) vasodilator responses were evaluated. NOS and COX inhibitors (L‐NAME and Indomethacin) were used to determine which endothelium‐dependent signaling pathways were altered.In all treatment groups endothelium‐dependent and ‐independent vasodilator responses were significantly impaired compared to controls (max ACh dilation: 91±2%). ACh‐induced vasodilation was less in the HU‐Rad (68±3%) group than in HU (79±1%) or Rad (80±2%) alone. Independent and simultaneous treatment with L‐NAME and indomethacin reduced vasodilation and eliminated group differences. Dea‐NONOate‐induced vasodilation was reduced to a greater degree in the Rad and HU‐Rad groups.These findings suggest that the combination of insults experienced during spaceflight lead to significant impairment of vasodilatory function, mediated through endothelium‐dependent reductions in NOS signaling and vascular smooth muscle dysfunction.Grant Funding Source: Supported by NSBRI, NCC 9‐58‐44

Rho-kinase inhibition improves vasodilator responsiveness during hyperinsulinemia in the metabolic syndrome

In patients with the metabolic syndrome (MetS), the facilitatory effect of insulin on forearm vasodilator responsiveness to different stimuli is impaired. Whether the RhoA/Rho kinase (ROCK) pathway is involved in this abnormality is unknown. We tested the hypotheses that, in MetS patients, ROCK inhibition with fasudil restores insulin-stimulated vasodilator reactivity and that oxidative stress plays a role in this mechanism. Endothelium-dependent and -independent forearm blood flow responses to acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, were assessed in MetS patients (n = 8) and healthy controls (n = 5) before and after the addition of fasudil (200 μg/min) to an intra-arterial infusion of insulin (0.1 mU/kg/min). In MetS patients (n = 5), fasudil was also infused without hyperinsulinemia. The possible involvement of oxidative stress in the effect of fasudil during hyperinsulinemia was investigated in MetS patients (n = 5) by infusing vitamin C (25 mg/min). In MetS patients, compared with saline, fasudil enhanced endothelium-dependent and -independent vasodilator responses during insulin infusion (P < 0.001 and P = 0.008, respectively), but not in the absence of hyperinsulinemia (P = 0.25 and P = 0.13, respectively). By contrast, fasudil did not affect vasoreactivity to ACh and SNP during hyperinsulinemia in controls (P = 0.11 and P = 0.56, respectively). In MetS patients, fasudil added to insulin and vitamin C did not further enhance vasodilation to ACh and SNP (P = 0.15 and P = 0.43, respectively). In the forearm circulation of patients with the MetS, ROCK inhibition by fasudil improves endothelium-dependent and -independent vasodilator responsiveness during hyperinsulinemia; increased oxidative stress seems to be involved in the pathophysiology of this phenomenon.

Early hypercholesterolemia contributes to vasomotor dysfunction and injury associated atherogenesis that can be inhibited by nitric oxide

Atherosclerosis results in vasomotor dysfunction, in part, through impairment of nitric oxide (NO) dependent vasodilation. It is unclear whether blood vessels are dysfunctional in an early environment of hypercholesterolemia alone and if this contributes to the vascular injury response. We hypothesize that early hypercholesterolemia, prior to gross vascular changes, contributes to vasomotor dysfunction and the vascular injury response. The efficacy of NO therapy to protect against the injury response in this setting was also assessed. The effect of oxidized low density lipoprotein (oxLDL) and inducible NO synthase (iNOS) gene transfer on rat aortic smooth muscle cell (SMC) proliferation was measured with (3)H-thymidine incorporation. Common carotid arteries (CCA) from wild-type C57BL6 (WT or C57) and apolipoprotein E deficient (ApoE KO) mice fed normal or Western diets for 6 to 8 weeks were tested for vasomotor function using an arteriograph system. Studies were repeated after CCA injury. The effect of iNOS gene transfer on morphometry by histology and vasomotor responses in injured CCAs in ApoE KO was examined. OxLDL increased SMC proliferation by >50%. In SMC expressing iNOS, NO production was unaffected by oxLDL and reduced oxLDL and still inhibited SMC proliferation. Endothelium dependent vasorelaxation was reduced in uninjured CCAs from ApoE KO and C57 mice on the Western vs normal diet (ApoE 39% ± 2% vs 55% ± 13%; C57 50% ± 13% vs 76% ± 5%, P < .001) and was increased with longer durations of hypercholesterolemia. Endothelium-dependent and independent vasodilator responses were severely disrupted in C57 and ApoE KO mice 2 weeks following CCA injury but both recovered by 4 weeks. CCA injury in ApoE KO mice resulted in the formation of atheromatous lesions while C57 mice showed no change (intima 27,795 ± 1829 vs 237 ± 28 μm(2); media 46,306 ± 2448 vs 11,714 ± 392 μm(2), respectively; P < .001). This structural change in the ApoE KO reduced distensibility and increased stiffness. Finally, iNOS gene transfer to injured CCA in ApoE KO mice dramatically reduced atheromatous neointimal lesion formation. Early hypercholesterolemia impairs endothelial function, with severity being related to duration and magnitude of hypercholesterolemia. Severe hypercholesterolemia leads to atheromatous lesion formation following injury and stresses the role of vascular injury in atherogenesis and suggests different mechanisms are involved in endothelial dysfunction and the injury response. Despite these changes, iNOS gene transfer still effectively inhibits atheroma formation. These findings support early correction of hypercholesterolemia and emphasize the potential role for NO based therapies in disease states.

Characterising the time-course of microvascular vasodilator responses in humans using laser doppler fluximetry and iontophoresis

Introduction Laser Doppler Fluximetry (LDF) and iontophoresis of vasodilators have been combined to assess microvascular flow and vasodilator reactivity in humans for many years and their use established. However, traditional data analysis methods measure the magnitude of flux change but not its time-course, a factor that may be of importance in defining vascular health. The aim of this study was to develop and utilise a novel data analysis method using a standardised LDF and iontophoresis protocol, assessing time to peak vasodilation (Tmax). Methods Endothelial-dependent and -independent vasodilator responses (using acetylcholine and sodium nitroprusside respectively) were measured in the perimalleolar region both supine and standing in patients with isolated superficial venous insufficiency (ISVI) ( n = 24) and controls ( n = 20), on two occasions. Tmax was measured at each post-iontophoretic period. Results Tmax was slower while standing and in patients with ISVI. There was no statistical difference in Tmax between visits for both groups ( p > 0.05), with coefficients of variation being between 20.2%–25.4%. ISVI, position and vasodilatory agents were significant determinants of Tmax. Discussion Tmax appears to be a reproducible method of assessing venous vasodilation, is not affected by the dose and is impaired in patients with of ISVI in both the supine and standing positions.

The effect of anti-tumor necrosis factor (TNF)-alpha therapy with etanercept on endothelial functions in patients with rheumatoid arthritis

To investigate the effects of tumor necrosis factor (TNF)- alpha antagonism with etanercept (ENC) on endothelial functions in patients with active rheumatoid arthritis (RA). A total of 21 patients with RA were enrolled in this prospective study. Eleven of them (8 women, 3 men mean age 47.0+/-10.1 years) with high disease activity despite the conventional treatment were assigned to Group 1 and were given ENC treatment twice a week (25 mg SC injection) for 12 weeks. Ten patients with RA (8 women, 2 men mean age 55.0+/-6.4 years) under conventional methotrexate and prednisone therapy were assigned as Control group (Group 2). Endothelium-dependent and -independent vasodilator responses of the brachial artery were assessed by high-resolution ultrasound. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were also measured at baseline and at the post treatment period. Mann-Whitney U and Wilcoxon tests were used to compare the data and correlation analysis was performed using Pearson correlation test. Endothelium-dependent vasodilatation improved from 5.2+/-0.8% to 7.9+/-1.3% (p=0.04) in ENC group, while no significant change was observed in the control group (from 6.6+/-1.1% to 7.0+/-1.8% p=0.67). No significant changes were found in endothelium-independent vasodilatation and baseline brachial artery diameters in both groups. A significant reduction in ESR and CRP were observed in patients receiving ENC (from 16.2+/-6.8 to 9.2+/-5.1 mm/h, p=0.003 and from 14.68+/-3.4 to 9.25+/-3.7 mg/L, p=0.003, respectively). Treatment with ENC for 12 weeks significantly improved endothelial function in patients with active RA compared to those under conventional therapy. The findings of the present study support the hypothesis that the use of TNF-alpha blockers in patients with active RA may reduce the high incidence of cardiovascular complications.

Dietary Intake of Fruits and Vegetables Improves Microvascular Function in Hypertensive Subjects in a Dose-Dependent Manner

Observational evidence has consistently linked increased fruit and vegetable consumption with reduced cardiovascular morbidity; however, there is little direct trial evidence to support the concept that fruit and vegetable consumption improves vascular function. This study assessed the dose-dependent effects of a fruit and vegetable intervention on arterial health in subjects with hypertension. After a 4-week run-in period during which fruit and vegetable intake was limited to 1 portion per day, participants were randomized to consume either 1, 3, or 6 portions daily for the next 8 weeks. Endothelium-dependent and -independent arterial vasodilator responses were assessed by venous occlusion plethysmography in the brachial circulation before and after intervention. Compliance was monitored with serial contemporaneous 4-day food records and by measuring concentrations of circulating dietary biomarkers. A total of 117 volunteers completed the 12-week study. Participants in the 1-, 3-, and 6-portions/d groups reported consuming on average 1.1, 3.2, and 5.6 portions of fruit and vegetables, respectively, and serum concentrations of lutein and beta-cryptoxanthin increased across the groups in a dose-dependent manner. For each 1-portion increase in reported fruit and vegetable consumption, there was a 6.2% improvement in forearm blood flow responses to intra-arterial administration of the endothelium-dependent vasodilator acetylcholine (P=0.03). There was no association between increased fruit and vegetable consumption and vasodilator responses to sodium nitroprusside, an endothelium-independent vasodilator. The present study illustrates that among hypertensive volunteers, increased fruit and vegetable consumption produces significant improvements in an established marker of endothelial function and cardiovascular prognosis.

Long-term consequences of polycystic ovary syndrome on cardiovascular risk

Most available data suggest that the prevalence of cardiovascular diseases in women with polycystic ovary syndrome (PCOS) is smaller than expected based on risk calculations during fertile years; therefore, more studies are needed on long-term cardiovascular consequences. Evidence is accumulating that postmenopausal women with PCOS have an increased risk of cerebrovascular events and cardiovascular morbidity. These events are partially related to persisting hyperandrogenism but are mostly correlated with excessive body weight (mainly visceral obesity); this suggests that our best long-term strategy is to ensure that women with PCOS are informed about their high risk for metabolic and cardiovascular diseases.

Abstract 5058: Dietary Intake of Fruits and Vegetables Improves Vascular Function in a Dose Dependent Manner - A Randomised Controlled Trial

Observational evidence has consistently linked increased fruit and vegetable consumption with reduced cardiovascular morbidity. However, there is little direct trial evidence to support the concept that fruit and vegetable consumption improves vascular function. This study has assessed the dose-dependent effects of a fruit and vegetable intervention on arterial health in subjects with hypertension. Following a common 4 week run-in period during which fruit and vegetable intake was limited to 1 portion/day, participants consumed either 1, 3 or 6 portions daily for the next 8 weeks. Endothelium-dependent and independent arterial vasodilator responses were assessed using venous occlusion plethysmography in the brachial circulation pre- and post-intervention. Compliance was monitored using serial contemporaneous 4-day food records and by measuring concentrations of circulating dietary biomarkers. A total of 118 volunteers completed the 12 week study. Participants in the 1, 3 and 6 portions/day groups reported consuming on average 1.1, 3.2 and 5.6 portions of fruit and vegetables respectively, while serum concentrations of ascorbic acid, lutein and β-cryptoxanthin increased across the groups in a dose-dependent manner. For each 1 portion increase in reported fruit and vegetable consumption, there was a 6.2% improvement in forearm blood flow responses to intra-arterial administration of the endothelium-dependent vasodilator acetylcholine (p=0.03). There was no association between increased fruit and vegetable consumption and vasodilator responses to sodium nitroprusside, an endothelium-independent vasodilator. This study illustrates that among hypertensive volunteers, increased fruit and vegetable consumption produces significant improvements in an established marker of endothelial function and cardiovascular prognosis.

Aging and ovariectomy alter endothelium‐dependent and –independent vasodilation in the femoral principal nutrient artery

Enhanced bone resorption and bone blood flow (BBF) occurs subsequent to ovariectomy (OVX) whereas BBF declines with age. The potential of the osseous resistance vasculature to alter BBF in postmenopausal and age‐related osteoporosis is unclear. PURPOSE: We studied the effects of age, gender, and estrogen status on endothelium‐dependent and ‐independent vasodilation of the femoral principal nutrient artery (PNA). METHODS: INTACT female (6‐, 14‐, and 24‐ mon), OVX female (6‐, 14‐, and 24‐ mon), and male (6‐ and 24‐ mon) Fischer‐344 rats were studied. PNAs were isolated and cannulated. Endothelium‐dependent (ACh: 10−9 – 10−4 M) and ‐independent (DEA NONOate: 10−10 – 10−4 M) vasodilation were assessed. RESULTS: Declines in endothelial function occurred in aged rats but no differences in gender were observed. Endothelium‐dependent vasodilation in young or middle‐aged rats did not change following OVX. In aged OVX rats, vasodilation was enhanced to similar values observed in young INTACT and young OVX rats. Endothelium‐independent vasodilation was not altered with age or gender except in middle aged OVX rats vs. their INTACT controls. DISCUSSION: These data demonstrate that OVX influences both endothelium‐dependent and –independent vasodilator responses of the osseous resistance vasculature. Supported by the NIH Grant #1 R01 HL077224‐01 (JMD) and the NHLBI Postdoctoral Supplement (RDP).

Intravascular tumor necrosis factor α blockade reverses endothelial dysfunction in rheumatoid arthritis

Patients with rheumatoid arthritis (RA) have endothelial dysfunction, which may predispose them to the risk of premature atherosclerosis. This study investigated the involvement of tumor necrosis factor (TNF) alpha in the pathophysiologic characteristics of this abnormality by use of the TNF-alpha-neutralizing antibody infliximab. Endothelium-dependent and -independent vasodilator responses to intra-arterial infusion of increasing doses of acetylcholine and sodium nitroprusside, respectively, were assessed by strain-gauge plethysmography in patients (n = 10) with early RA during saline solution infusion and after intra-arterial infusion of infliximab (200 microg/min). Circulating markers of systemic inflammation (C-reactive protein and interleukin 6) were higher in patients than in control subjects (n = 10, both P < .05), whereas plasma levels of TNF-alpha and soluble TNF receptor types 1 and 2 were similar in both groups (all P > .05). During saline solution infusion, the vasodilator response to acetylcholine was blunted in patients with RA compared with control subjects (14.2 +/- 9.2 mL . min-(1). dL-(1) versus 23.7 +/- 9.2 mL . min-(1). dL-(1) at the highest dose, P = .004) whereas vasodilation to sodium nitroprusside was not different between groups (P = .10). In patients with RA infliximab did not modify circulating C-reactive protein levels (P = .29, versus saline solution) but did potentiate the vasodilator response to acetylcholine (21.0 +/- 11.1 mL . min-(1). dL-(1); P = .004, versus saline solution). The response to sodium nitroprusside, in contrast, was not modified by infliximab (P = .28 versus saline solution). Intravascular administration of anti-TNF-alpha antibody ameliorates endothelial function in patients with RA but does not concurrently affect systemic inflammatory changes. Our findings suggest that enhanced TNF-alpha generation within the vessel wall, rather than systemic mechanisms, plays a role in the pathobiologic features of endothelial dysfunction in RA.

Ghrelin Improves Endothelial Function in Patients With Metabolic Syndrome

Metabolic syndrome importantly accelerates the atherosclerotic process, the earliest event of which is endothelial dysfunction. Ghrelin, a gastric peptide with cardiovascular actions, has been shown to inhibit proatherogenic changes in experimental models. This study therefore investigated whether ghrelin administration might beneficially affect endothelial function in metabolic syndrome. Endothelium-dependent and -independent vasodilator responses to intra-arterial infusion of increasing doses of acetylcholine and sodium nitroprusside (SNP), respectively, were assessed by strain-gauge plethysmography before and after local administration of human ghrelin (200 microg/min). During saline, the vasodilator response to acetylcholine was significantly blunted (P=0.008) in patients with metabolic syndrome (n=12, 5 female) compared with controls (n=12, 7 female), whereas the vasodilator response to SNP was not different between groups (P=0.68). In patients with metabolic syndrome, basal plasma ghrelin was significantly lower than in controls (P=0.02). In these patients, ghrelin infusion markedly increased intravascular concentrations of the peptide (P<0.001) and resulted in a potentiation of the vasodilator response to acetylcholine (P=0.001 versus saline) but not to SNP (P=0.22). This effect was likely related to enhanced nitric oxide bioavailability because, in a group of patients with metabolic syndrome (n=6, 2 female), ghrelin had no effect on the vasodilator response to acetylcholine (P=0.78 versus saline) after nitric oxide inhibition by NG-monomethyl-L-arginine. These findings indicate that ghrelin reverses endothelial dysfunction in patients with metabolic syndrome by increasing nitric oxide bioactivity, thereby suggesting that decreased circulating levels of the peptide, such as those found in these patients, might play a role in the pathobiology of atherosclerosis.

Effects of cerivastatin on forearm vascular responses, blood pressure responsiveness and ambulatory blood pressure in type 2 diabetic men

The objective of the study was to investigate the effects of cerivastatin therapy on forearm endothelial dependent acetylcholine (ACH) and independent (nitroprusside) vasodilator responses, blood pressure (BP) responses to intravenous infusions of angiotensin II (AII) and noradrenaline (NA) and on 24-h ambulatory BP recordings in type 2 diabetic men. Eleven type 2 diabetic men aged 59 +/- 9 years with total cholesterol levels of 5.0 +/- 1.26 mmol/l, triglycerides of 2.23 mmol/l and high-density lipoprotein cholesterol levels of 1.24 mmol/l completed a double-blind, randomized, crossover trial comparing 8 weeks of cerivastatin therapy (800 microg of nocte) with placebo. Forearm vascular resistance (FVR) responses to intrabrachial-arterial infusions of ACH (3-24 microg/min), nitroprusside (2-16 microg/min), the nitric oxide(NO) synthase inhibitor l-nitro-mono-methyl arginine (l-nmma) (8 micromol/min), ACH during l-NMMA infusion and BP responses to intravenous infusions of AII (12.5-50 ng/min) and NA (20-400 ng/min) were measured at the end of each treatment period. Twenty-four-hour ambulatory BP recordings were also performed. FVR responses to ACH during l-NMMA infusion were significantly (p = 0.026) greater during cerivastatin than during placebo therapy. In contrast, FVR responses to ACH in the absence of NO synthase inhibition did not differ significantly between cerivastatin and placebo therapies (p = 0.81). FVR increased by 31.4 +/- 57.3% in response to l-NMMA infusion during cerivastatin therapy compared with 6.1 +/- 41.2% during placebo therapy (p = 0.20). FVR responses to nitroprusside did not differ between cerivastatin and placebo therapies (p = 0.28), nor did BP responses to AII (systolic BP, p = 0.99; diastolic BP, p = 0.98) or NA (systolic BP, p = 0.21; diastolic BP, p = 0.48). Mean 24-h BP was similar during cerivastatin (123 +/- 10 or 70 +/- 7 mmHg) and placebo therapies (129 +/- 11 or 74 +/- 7 mmHg) (systolic BP, p = 0.26; diastolic BP, p = 0.41). Cerivastatin increases FVR responses to ACH in type 2 diabetic men with mild dyslipidaemia but only following NO synthase inhibition. This may indicate an improvement in endothelium-derived hyperpolarizing factor-mediated responses.