Abstract-Increased endothelin-1-mediated vasoconstrictor tone has been linked to the etiology of a number of pathologies associated with human aging, including hypertension, congestive heart failure, and coronary artery disease. However, it is currently unclear whether aging, per se, is associated with enhanced endothelin-1 system activity. We hypothesized that endothelin-1 vasoconstrictor activity is greater in healthy older compared with young men and that regular aerobic exercise is an effective intervention for reducing endothelin-1 vasoconstrictor tone in older previously sedentary men. Forearm blood flow (plethysmography) responses to intra-arterial infusion of endothelin-1 (5 pmol/min; for 20 minutes) and selective (BQ-123; 100 nmol/min; for 60 minutes) and nonselective (BQ-123ϩBQ-788; 100 nmol/min; for 60 minutes) endothelin-1 receptor blockade were determined in 28 healthy, sedentary men: 13 younger (age: 27Ϯ1 years) and 15 older (age: 62Ϯ2 years). The vasoconstrictor response to endothelin-1 was significantly blunted (Ϸ65%) in the older versus younger men. In response to BQ-123, resting forearm blood flow increased (Ϸ20%; PϽ0.05) in the older but not in the younger men. Key Words: elderly Ⅲ exercise Ⅲ endothelin Ⅲ blood flow regulation M any of the cardiovascular complications associated with aging (eg, hypertension, arterial spasm, and myocardial infarction) are attributable, at least in part, to endothelial dysfunction, particularly vasomotor dysregulation. 1-3 Impaired vasomotor function occurs early in the atherosclerotic process, contributes to disease development and progression, and can trigger acute cardiovascular events. 4 -6 In addition to the synthesis and release of relaxing factors, such as NO, the vascular endothelium also produces contracting factors, the most potent of which is endothelin (ET)-1. Produced by the proteolytic cleavage of big ET-1 by ET converting enzyme, endothelial ET-1 is predominantly (Ͼ80%) released abluminally toward the vascular smooth muscle. 7 Binding of ET-1 to ET A and ET B receptors on vascular smooth muscle cells activates the phospholipase C-inositol triphosphate pathway resulting in an increase in intracellular calcium causing phosphorylation of myosin kinase and, in turn, long-lasting smooth muscle cell contraction. 7,8 Importantly, increased ET-1-mediated vasoconstriction has been linked to the etiology of a number of cardiovascular pathologies, including hypertension, vasospasm, coronary artery disease, and chronic heart failure. 8 -10 There is strong evidence in animal models that aging is associated with elevated ET-1 system activation. 11,12 However, data regarding the influence of aging on ET-1 system activity in adult humans are limited. Kumazaki et al 13 reported that cultured endothelial cells from the aorta of adults over the age of 50 years produce and release more ET-1 compared with cells from younger adults. Some studies have reported age-related increases in circulating levels of ET-1 14,15 ; however, the pathophysiological significance of ...

Objective: Both obesity and the metabolic syndrome (MetS) have been independently linked with increased oxidative and inflammatory stress. This study tested the hypothesis that obesity with MetS is associated with greater oxidative and inflammatory burden compared with obesity alone. Research Methods and Procedures: Forty‐eight normal‐weight and 40 obese (20 without MetS; 20 with MetS) adults were studied. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria. Plasma concentrations of oxidized low‐density lipoprotein, C‐reactive protein, tumor necrosis factor‐α, interleukin (IL)‐6, and IL‐18 were determined by enzyme immunoassay. Results: Plasma biomarkers of oxidative stress and inflammation were lowest in normal‐weight controls. Of note, obese MetS adults demonstrated significantly higher plasma concentrations of oxidized low‐density lipoprotein (62.3 ± 3.2 vs. 54.0 ± 4.0 U/L; p < 0.05), C‐reactive protein (3.0 ± 0.6 vs. 1.5 ± 0.3 mg/L; p < 0.01), tumor necrosis factor‐α (2.1 ± 0.1 vs. 1.6 ± 0.1 pg/mL; p < 0.05), IL‐6 (2.8 ± 0.4 vs. 1.4 ± 0.2 pg/mL; p < 0.01), and IL‐18 (253 ± 16 vs. 199 ± 16 pg/mL; p < 0.01), compared with obese adults without MetS. Discussion: These results suggest that MetS heightens oxidative stress and inflammatory burden in obese adults. Increased oxidative and inflammatory stress may contribute to the greater risk of coronary heart disease and cerebrovascular disease in obese adults with MetS.

Numerical and functional impairment of circulating endothelial progenitor cells (EPCs) is thought to contribute to vascular aging and the associated increase in cardiovascular risk. We tested the following hypotheses: 1) EPC clonogenic and migratory capacity decrease progressively with age in healthy, sedentary adult men; and 2) regular aerobic exercise will improve EPC clonogenic and migratory capacity in previously sedentary middle-aged and older men. Peripheral blood samples were collected from 46 healthy sedentary men: 10 young (26 +/- 1 yr), 15 middle-aged (47 +/- 1 yr), and 21 older (63 +/- 1 yr). Mononuclear cells were isolated and preplated for 2 days, and nonadherent cells were further cultured for 7 days to determine EPC colony-forming units. Migratory activity of EPCs was determined using a modified Boyden chamber. Ten sedentary middle-aged and older men (59 +/- 3 yr) were studied before and after a 3-mo aerobic exercise intervention. The number of EPC colony-forming units was approximately 75% lower (P < 0.01) in middle-aged (12 +/- 3) and older (8 +/- 2) compared with young (40 +/- 7) men. There was no difference in colony count between middle-aged and older men. EPC migration (fluorescent units) was significantly reduced in older (453 +/- 72) compared with young (813 +/- 114) and middle-aged (760 +/- 114) men. The exercise intervention increased (P < 0.05) both EPC colony-forming units (10 +/- 3 to 22 +/- 5) and migratory activity (683 +/- 96 to 1,022 +/- 123) in previously sedentary middle-aged and older men. These results provide further evidence that aging adversely affects EPC function. Regular aerobic-endurance exercise, however, is an effective lifestyle intervention strategy for improving EPC clonogenic and migratory capacity in middle-aged and older healthy men.

Endothelin (ET)-1-mediated vasoconstrictor tone contributes to the development and progression of several adiposity-related conditions, including hypertension and atherosclerotic vascular disease. The aims of the present study were to determine 1) whether endogenous ET-1 vasoconstrictor activity is elevated in overweight and obese adults, and, if so, 2) whether increased ET-1-mediated vasoconstriction contributes to the adiposity-related impairment in endothelium-dependent vasodilation. Seventy-nine adults were studied: 34 normal weight [body mass index (BMI) < 25 kg/m(2)], 22 overweight (BMI ≥ 25 and < 30 kg/m(2)), and 23 obese (BMI ≥ 30 kg/m(2)). Forearm blood flow (FBF) responses to intra-arterial infusion of ET-1 (5 pmol/min for 20 min) and selective ET-1 receptor blockade (BQ-123, 100 nmol/min for 60 min) were determined. In a subset of the study population, FBF responses to ACh (4.0, 8.0, and 16.0 μg·100 ml tissue(-1)·min(-1)) were measured in the absence and presence of selective ET-1 receptor blockade. The vasoconstrictor response to ET-1 was significantly blunted in overweight and obese adults (∼ 70%) compared with normal weight adults. Selective ET-1 receptor blockade elicited a significant vasodilator response (∼ 20%) in overweight and obese adults but did not alter FBF in normal weight adults. Coinfusion of BQ-123 did not affect FBF responses to ACh in normal weight adults but resulted in an ∼ 20% increase (P < 0.05) in ACh-induced vasodilation in overweight and obese adults. These results demonstrate that overweight and obesity are associated with enhanced ET-1-mediated vasoconstriction that contributes to endothelial vasodilator dysfunction and may play a role in the increased prevalence of hypertension with increased adiposity.

. Endothelial t-PA release is impaired in overweight and obese adults but can be improved with regular aerobic exercise. Am J Physiol Endocrinol Metab 289: E807-E813, 2005. First published June 28, 2005; doi:10.1152/ajpendo.00072.2005.-Endothelial release of tissue-type plasminogen activator (t-PA) regulates fibrinolysis and is considered to be a primary endogenous defense mechanism against thrombosis. Adiposity is associated with an increased risk of atherothrombotic events. We determined the influence of overweight and obesity on the capacity of the vascular endothelium to release t-PA and the effects of regular aerobic exercise on endothelial t-PA release in previously sedentary overweight and obese adults. First, we studied 66 sedentary adults: 28 normal-weight (BMI Ͻ25 kg/m 2 ); 22 overweight (BMI Ն25 and Ͻ30 kg/m 2 ); and 16 obese (BMI Ն30 kg/m 2 ). Net endothelial t-PA release was determined in vivo in response to intrabrachial infusions of bradykinin (BK) and sodium nitroprusside. Second, we studied 17 overweight and obese adults who completed a 3-mo aerobic exercise intervention. Net release of t-PA in response to BK was ϳ45% lower (P Ͻ 0.01) in overweight (from 0.1 Ϯ 0.4 to 41.7 Ϯ 4.9 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 ) and obese (Ϫ0.1 Ϯ 0.6 to 47.7 Ϯ 5.2 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 ) compared with normal-weight (0.1 Ϯ 0.8 to 77.5 Ϯ 6.7 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 ) adults. There was no difference in t-PA release between the overweight and obese groups. Exercise training significantly increased t-PA release capacity in overweight and obese adults (from Ϫ0.3 Ϯ 0.5 to 37.1 Ϯ 4.9 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 before training vs. 1.0 Ϯ 0.9 to 65.4 Ϯ 6.3 ng ⅐ 100 ml tissue Ϫ1 ⅐ min Ϫ1 after training) to levels comparable with those of their normal-weight peers. These results indicate that overweight and obesity are associated with profound endothelial fibrinolytic dysfunction. Importantly, however, regular aerobic exercise can increase the capacity of the endothelium to release t-PA in this at-risk population.endothelium; fibrinolysis; tissue-type plasminogen activator RECENT ESTIMATES INDICATE that over 60% of the adult population in the United States is either overweight or obese (21). Moreover, the incidence of overweight and obesity is highest in middle-aged and older adults and is thought to contribute to the increased risk of coronary artery disease, cerebrovascular disease, and atherothrombotic events in this segment of the population (37,39,40).It is now well accepted that endothelial dysfunction plays an important role in the initiation and progression of atherosclerosis (5, 45). A potential mechanism underlying the heightened atherothrombotic risk with obesity is impaired endothelial control of fibrinolysis. Endothelial cells are the principal site of synthesis and release of tissue-type plasminogen activator (t-PA), the key enzyme in initiating an endogenous fibrinolytic response, due to its ability to preferentially activate plasminogen on the surface of developing thrombi (15). Experimental...

Middle-aged women have a lower prevalence and incidence of cardiovascular events than men. The mechanisms responsible for this sex-specific difference are unclear. Numerical and functional impairment of bone marrow-derived circulating endothelial progenitor cells (EPCs) is associated with increased cardio-and cerebrovascular morbidity and mortality. It is currently unknown whether there are sex-related differences in EPC number and function in middle-aged adults. We tested the hypothesis that EPCs isolated from middle-aged women demonstrate greater colony forming capacity and migratory activity compared with men of similar age. Peripheral blood samples were collected from 50 sedentary adults; 25 men (age: 59±1 yr) and 25 women (58±1 yr). Mononuclear cells were isolated, preplated for 2 days and nonadherent cells were further cultured for 7 days to determine EPC colony forming units. Migratory activity of EPCs was determined using a modified Boyden chamber. The number of EPC colony forming units was significantly higher (∼150%) in samples collected from women (16±3) compared with men (7±1). In addition, EPC migration (relative fluorescent units) was ∼40% greater in women (729±74) versus men (530±67). These results demonstrate that EPC colony forming capacity and migratory activity are higher in middle-aged women compared with men. Keywordsendothelial progenitor cells; colony-forming units; migration Cardiovascular disease is the most frequent cause of death in both men and women. However, between the ages of 45 and 65 years, the prevalence of coronary heart disease and the incidence of myocardial infarction and stroke is ∼50% higher in men compared with women. The mechanisms responsible for this sex-related disparity are currently unclear. Interestingly, there are no apparent sex differences in the incidence and prevalence of traditional cardiovascular disease risk factors such as hypertension, obesity, tobacco use, hyperlipidemia, diabetes, or sedentary lifestyle in middle-aged adults 1 . Clinical interest in bone marrow-derived circulating endothelial progenitor cells as a novel vascular risk factor has increased due to their importance in vascular repair and noted inverse relation with endothelial dysfunction as well as cardiovascular and cerebrovascular disease 2-4 . Indeed, reduced EPC number and migratory activity have been linked to atherosclerotic disease progression and cardiovascular events This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptAm J Cardiol. Author manuscript; available in PMC 2008 January 1. NIH-PA Author ManuscriptNIH-PA Author Man...

Muscarinic receptor agonists have primarily been used to characterize endothelium-dependent vasodilator dysfunction with overweight/obesity. Reliance on a single class of agonist, however, yields limited, and potentially misleading, information regarding endothelial vasodilator capacity. The aims of this study were to determine 1) whether the overweight/obesity-related reduction in endothelium-dependent vasodilation extends beyond muscarinic receptor agonists and 2) whether the contribution of nitric oxide (NO) to endothelium-dependent vasodilation is reduced in overweight/obese adults. Eighty-six middle-aged and older adults were studied: 42 normal-weight (54 ± 1 yr, 21 men and 21 women, body mass index = 23.4 ± 0.3 kg/m 2 ) and 44 overweight/obese (54 ± 1 yr, 28 men and 16 women, body mass index = 30.3 ± 0.6 kg/m 2 ) subjects. Forearm blood flow (FBF) responses to intra-arterial infusions of acetylcholine in the absence and presence of the endothelial NO synthase inhibitor N G -monomethyl-L-arginine, methacholine, bradykinin, substance P, isoproterenol, and sodium nitroprusside were measured by strain-gauge plethysmography. FBF responses to each endothelial agonist were significantly blunted in the overweight/obese adults. Total FBF (area under the curve) to acetylcholine (50 ± 5 vs. 79 ± 4 ml/ 100 ml tissue), methacholine (55 ± 4 vs. 86 ± 5 ml/100 ml tissue), bradykinin (62 ± 5 vs. 85 ± 4 ml/100 ml tissue), substance P (37 ± 4 vs. 57 ± 5 ml/100 ml tissue), and isoproterenol (62 ± 4 vs. 82 ± 6 ml/100 ml tissue) were 30%-40% lower in the overweight/obese than normal-weight adults. N G -monomethyl-L-arginine significantly reduced the FBF response to acetylcholine to the same extent in both groups. There were no differences between the groups in the FBF responses to sodium nitroprusside. These results indicate that agonist-stimulated endothelium-dependent vasodilation is universally impaired with overweight/ obesity. Moreover, this impairment appears to be independent of NO. NIH Public Access Author ManuscriptAm J Physiol Heart Circ Physiol. Impaired endothelium-dependent vasodilation, a hallmark characteristic of endothelial dysfunction, has been linked etiologically to the initiation and development of atherosclerotic vascular disease (25,35). Indeed, reduced endothelium-mediated vasodilation occurs early in atherogenesis, before histological and/or angiographic evidence of disease (38). Endothelial function, particularly endothelium-dependent vasodilation, is impaired in overweight and obese adults and is thought to contribute to their increased risk of coronary artery disease, cerebrovascular disease, and atherothrombotic events (23,24,29,30,32) The mechanisms responsible for the adiposity-related reduction in endothelial vasodilator function in adult humans are not completely understood. Pharmacological studies have primarily employed muscarinic receptor agonists, acetylcholine or methacholine, to assess the influence of increased body fatness on endothelium-dependent vasodilation (23,30,31). The re...

ObjectiveTo investigate whether adiposity influences endothelial progenitor cell (EPC) number and colony-forming capacity.DesignCross-sectional study of normal weight, overweight and obese adult humans.SubjectsSixty-seven sedentary adults (age 45–65y): 25 normal weight (BMI ≤ 25 kg/m2; 12 males/13 females); 18 overweight (BMI = 25–29.9 kg/m2; 12 males/6 females); and 24 obese (BMI ≥ 30 kg/m2; 18 males/6 females). All subjects were non-smokers and free of overt cardiometabolic disease.MeasurementsPeripheral blood samples were collected and circulating EPC number was assessed by flow cytometry. Putative EPCs were defined as CD45−/CD34+/VEGFR-2+/CD133+ or CD45−/CD34+ cells. EPC colony-forming capacity was measured in vitro using a colony-forming unit assay.ResultsNumber of circulating putative EPCs (either CD45−/CD34+/VEGFR-2+/CD133+ or CD45−/CD34+ cells) was lower (P<0.05) in obese (0.0007±0.0001%; 0.050±0.006%) compared with overweight (0.0016±0.0004%; 0.089±0.019%) and normal weight (0.0015±0.0003%; 0.082±0.008%) adults. There were no differences in EPC number between the overweight and normal weight groups. EPC colony-formation was significantly less in the obese (6±1) and overweight (4±1) compared with normal weight (9±2) adults.ConclusionThese results indicate that: 1) the number of circulating EPCs is lower in obese compared with overweight and normal weight adults; and 2) EPC colony-forming capacity is blunted in overweight and obese adults compared with normal weight adults. Impairments in EPC number and function may contribute to adiposity-related cardiovascular risk.