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Stephens BY, Young BE, Nandadeva D, Skow RJ, Greaney JL, Brothers RM, Fadel PJ. Sympathetic transduction at rest and during cold pressor test in young healthy non-Hispanic Black and White women. Am J Physiol Regul Integr Comp Physiol 2023; 325:R682-R691. [PMID: 37781734 PMCID: PMC11178294 DOI: 10.1152/ajpregu.00073.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/03/2023]
Abstract
Non-Hispanic Black (BL) individuals have the highest prevalence of hypertension and cardiovascular disease (CVD) compared with all other racial/ethnic groups. Previous work focused on racial disparities in sympathetic control and blood pressure (BP) regulation between young BL and White (WH) adults, have mainly included men. Herein, we hypothesized that BL women would exhibit augmented resting sympathetic vascular transduction and greater sympathetic and BP reactivity to cold pressor test (CPT) compared with WH women. Twenty-eight young healthy women (BL: n = 14, 22 [Formula: see text] 4 yr; WH: n = 14, 22 [Formula: see text] 4 yr) participated. Beat-to-beat BP (Finometer), common femoral artery blood flow (duplex Doppler ultrasound), and muscle sympathetic nerve activity (MSNA; microneurography) were continuously recorded. In a subset (BL n = 10, WH n = 11), MSNA and BP were recorded at rest and during a 2-min CPT. Resting sympathetic vascular transduction was quantified as changes in leg vascular conductance (LVC) and mean arterial pressure (MAP) following spontaneous bursts of MSNA using signal averaging. Sympathetic and BP reactivity were quantified as changes in MSNA and MAP during the last minute of CPT. There were no differences in nadir LVC following resting MSNA bursts between BL (-8.70 ± 3.43%) and WH women (-7.30 ± 3.74%; P = 0.394). Likewise, peak increases in MAP following MSNA bursts were not different between groups (BL: +2.80 ± 1.42 mmHg; vs. WH: +2.99 ± 1.15 mmHg; P = 0.683). During CPT, increases in MSNA and MAP were also not different between BL and WH women, with similar transduction estimates between groups (ΔMAP/ΔMSNA; P = 0.182). These findings indicate that young, healthy BL women do not exhibit exaggerated sympathetic transduction or augmented sympathetic and BP reactivity during CPT.NEW & NOTEWORTHY This study was the first to comprehensively investigate sympathetic vascular transduction and sympathetic and BP reactivity during a cold pressor test in young, healthy BL women. We demonstrated that young BL women do not exhibit exaggerated resting sympathetic vascular transduction and do not have augmented sympathetic or BP reactivity during cold stress compared with their WH counterparts. Collectively, these findings suggest that alterations in sympathetic transduction and reactivity are not apparent in young, healthy BL women.
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Affiliation(s)
- Brandi Y Stephens
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Damsara Nandadeva
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
- Department of Physiology, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
| | - Rachel J Skow
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Jody L Greaney
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - R Matthew Brothers
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
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Akins JD, Richey RE, Campbell JC, Martin ZT, Olvera G, Brothers RM. Contributions of endothelin-1 and l-arginine to blunted cutaneous microvascular function in young, black women. Am J Physiol Heart Circ Physiol 2022; 322:H260-H268. [PMID: 34919455 PMCID: PMC8759956 DOI: 10.1152/ajpheart.00457.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Non-Hispanic black (BL) individuals have the greatest prevalence of cardiovascular disease (CVD), relative to other racial/ethnic groups (e.g., non-Hispanic white population; WH), which may be secondary to blunted vascular function. Although women typically present with reduced CVD relative to men of the same racial/ethnic group, the prevalence is similar between BL women and men though the mechanisms differ. This study hypothesized that reduced microvascular function in young, BL women is associated with endothelin-1 (ET-1) overactivity or insufficient l-arginine bioavailability. Nine BL and nine WH women participated (age: 20 ± 2 vs. 22 ± 2 yr). Cutaneous microvascular function was assessed during 39°C local heating, whereas lactated Ringer's (control), BQ-123 (ET-1 receptor type A antagonist), BQ-788 (ET-1 receptor type B antagonist), or l-arginine were infused via intradermal microdialysis to modify cutaneous vascular conductance (CVC). Subsequent infusion of Nω-nitro-l-arginine methyl ester allowed for quantification of the nitric oxide (NO) contribution to vasodilation, whereas combined sodium nitroprusside and 43°C heating allowed for normalization to maximal CVC (%CVCmax). BL women had blunted %CVCmax and NO contribution to dilation during the 39°C plateau (P < 0.027 for both). BQ-123 improved this response through augmented NO-mediated dilation (P < 0.048 for both). BQ-788 and l-arginine did not alter the CVC responses (P > 0.835 for both) or the NO contribution (P > 0.371 for both). Cutaneous microvascular function is reduced in BL women, and ET-1 receptor type A may contribute to this reduced function. Further research is needed to better characterize these mechanisms in young, BL women.NEW & NOTEWORTHY Cardiovascular disease remains a burden in the United States non-Hispanic black (BL) population, although its manifestation through blunted vasodilation in this population is different between men and women. Accordingly, this study determined that reduced microvascular function in young, BL women may be partially controlled by endothelin-1 (ET-1) type A receptors, although neither type B receptors nor insufficient l-arginine bioavailability seems to contribute to this response. Accordingly, further research is needed to better characterize these ET-1 related mechanisms and illuminate other pathways that may contribute to this disparate vascular function in young, BL women.
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Affiliation(s)
- John D. Akins
- 1Department of Kinesiology, The University of Texas at Arlington, Arlington, Texas
| | - Rauchelle E. Richey
- 1Department of Kinesiology, The University of Texas at Arlington, Arlington, Texas,2Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas
| | - Jeremiah C. Campbell
- 1Department of Kinesiology, The University of Texas at Arlington, Arlington, Texas
| | - Zachary T. Martin
- 1Department of Kinesiology, The University of Texas at Arlington, Arlington, Texas
| | - Guillermo Olvera
- 1Department of Kinesiology, The University of Texas at Arlington, Arlington, Texas,3Institute for Exercise and Environmental Medicine, Dallas, Texas
| | - R. Matthew Brothers
- 1Department of Kinesiology, The University of Texas at Arlington, Arlington, Texas
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3
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Brothers RM, Stephens BY, Akins JD, Fadel PJ. Influence of sex on heightened vasoconstrictor mechanisms in the non-Hispanic black population. FASEB J 2020; 34:14073-14082. [PMID: 32949436 DOI: 10.1096/fj.202001405r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/20/2020] [Accepted: 08/27/2020] [Indexed: 11/11/2022]
Abstract
Cardiovascular disease (CVD) affects individuals of all races and ethnicities; however, its prevalence is highest in non-Hispanic black individuals (BL) relative to other populations. While previous research has provided valuable insight into elevated CVD risk in the BL population, this work has been almost exclusively conducted in men. This is alarming given that BL women suffer from CVD at an equivalent rate to BL men and each has a greater prevalence when compared to all other ethnicities, regardless of sex. The importance of investigating sex differences in mechanisms of cardiovascular function is highlighted by the National Institute of Health requiring sex to be considered as a biological variable in research studies to better our "understanding of key sex influences on health processes and outcomes." The mechanism(s) responsible for the elevated CVD risk in BL women remains unclear and is likely multifactorial. Limited studies in BL women suggest that, while impaired vasodilator capacity is involved, heightened vasoconstrictor tone and/or responsiveness may also contribute. Within this mini-review, we will discuss potential mechanisms of elevated rates of hypertension and other CVDs in BL individuals with a particular focus on young, otherwise healthy, college-aged women. To stimulate academic thought and future research, we will also discuss potential mechanisms for impaired vascular function in BL women, as well as possible divergent mechanisms between BL men and women based on either preliminary data or plausible speculation extending from findings in the existing literature. Last, we will conclude with potential future research directions aimed at better understanding the elevated risk for hypertension and CVD in BL women.
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Affiliation(s)
| | | | - John D Akins
- Department of Kinesiology, University of Texas, Arlington, TX, USA
| | - Paul J Fadel
- Department of Kinesiology, University of Texas, Arlington, TX, USA
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4
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Brothers RM, Fadel PJ, Keller DM. Racial disparities in cardiovascular disease risk: mechanisms of vascular dysfunction. Am J Physiol Heart Circ Physiol 2019; 317:H777-H789. [PMID: 31397168 DOI: 10.1152/ajpheart.00126.2019] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cardiovascular disease (CVD) accounts for a third of all deaths in the United States making it the leading cause of morbidity and mortality. Although CVD affects individuals of all races/ethnicities, the prevalence of CVD is highest in non-Hispanic black (BL) individuals relative to other populations. The mechanism(s) responsible for elevated CVD risk in the BL population remains incompletely understood. However, impaired vascular vasodilator capacity and exaggerated vascular vasoconstrictor responsiveness are likely contributing factors, both of which are present even in young, otherwise healthy BL individuals. Within this review, we highlight some historical and recent data, collected from our laboratories, of impaired vascular function, in terms of reduced vasodilator capacity and heightened vasoconstrictor responsiveness, in the peripheral and cerebral circulations in BL individuals. We provide data that such impairments may be related to elevated oxidative stress and subsequent reduction in nitric oxide bioavailability. In addition, divergent mechanisms of impaired vasodilatory capacity between BL men and women are discussed. Finally, we propose several directions where future research is needed to fill in knowledge gaps, which will allow for better understanding of the mechanisms contributing to impaired vascular function in this population. Ultimately, this information will allow for better lifestyle and therapeutic approaches to be implemented in an effort to minimize the increased CVD burden in the BL population.
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Affiliation(s)
- R Matthew Brothers
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
| | - David M Keller
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas
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5
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De Miguel C, Sedaka R, Kasztan M, Lever JM, Sonnenberger M, Abad A, Jin C, Carmines PK, Pollock DM, Pollock JS. Tauroursodeoxycholic acid (TUDCA) abolishes chronic high salt-induced renal injury and inflammation. Acta Physiol (Oxf) 2019; 226:e13227. [PMID: 30501003 DOI: 10.1111/apha.13227] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 10/23/2018] [Accepted: 11/22/2018] [Indexed: 12/23/2022]
Abstract
AIM Chronic high salt intake exaggerates renal injury and inflammation, especially with the loss of functional ETB receptors. Tauroursodeoxycholic acid (TUDCA) is a chemical chaperone and bile salt that is approved for the treatment of hepatic diseases. Our aim was to determine whether TUDCA is reno-protective in a model of ETB receptor deficiency with chronic high salt-induced renal injury and inflammation. METHODS ETB -deficient and transgenic control rats were placed on normal (0.8% NaCl) or high salt (8% NaCl) diet for 3 weeks, receiving TUDCA (400 mg/kg/d; ip) or vehicle. Histological and biochemical markers of kidney injury, renal cell death and renal inflammation were assessed. RESULTS In ETB -deficient rats, high salt diet significantly increased glomerular and proximal tubular histological injury, proteinuria, albuminuria, excretion of tubular injury markers KIM-1 and NGAL, renal cortical cell death and renal CD4+ T cell numbers. TUDCA treatment increased proximal tubule megalin expression as well as prevented high salt diet-induced glomerular and tubular damage in ETB -deficient rats, as indicated by reduced kidney injury markers, decreased glomerular permeability and proximal tubule brush border restoration, as well as reduced renal inflammation. However, TUDCA had no significant effect on blood pressure. CONCLUSIONS TUDCA protects against the development of glomerular and proximal tubular damage, decreases renal cell death and inflammation in the renal cortex in rats with ETB receptor dysfunction on a chronic high salt diet. These results highlight the potential use of TUDCA as a preventive tool against chronic high salt induced renal damage.
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Affiliation(s)
- Carmen De Miguel
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Randee Sedaka
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Malgorzata Kasztan
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Jeremie M. Lever
- Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Michelle Sonnenberger
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Andrew Abad
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Chunhua Jin
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Pamela K. Carmines
- Department of Cellular and Integrative Physiology University of Nebraska Medical Center Omaha Nebraska
| | - David M. Pollock
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
| | - Jennifer S. Pollock
- Section of Cardio‐Renal Physiology and Medicine, Division of Nephrology, Department of Medicine University of Alabama at Birmingham Birmingham Alabama
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6
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Khera R, Vaughan-Sarrazin M, Rosenthal GE, Girotra S. Racial disparities in outcomes after cardiac surgery: the role of hospital quality. Curr Cardiol Rep 2015; 17:29. [PMID: 25894800 PMCID: PMC4780328 DOI: 10.1007/s11886-015-0587-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Patients from racial and ethnic minorities experience higher mortality after cardiac surgery compared to white patients, both during the early postoperative phase as well as long term. A number of factors likely explain poor outcomes in black and minority patients, which include differences in biology, comorbid health conditions, socioeconomic background, and quality of hospital care. Recent evidence suggests that a major factor underlying excess mortality in these groups is due to their over-representation in low-quality hospitals, where all patients regardless of race have worse outcomes. In this review, we examine the factors underlying racial disparities in outcomes after cardiac surgery, with a primary focus on the role of hospital quality.
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Affiliation(s)
- Rohan Khera
- Department of Internal Medicine, University of Iowa Hospitals & Clinics, 200 Hawkins Drive, E325 GH, Iowa City, IA, 52242, USA,
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7
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Kohan DE, Rossi NF, Inscho EW, Pollock DM. Regulation of blood pressure and salt homeostasis by endothelin. Physiol Rev 2011; 91:1-77. [PMID: 21248162 DOI: 10.1152/physrev.00060.2009] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Endothelin (ET) peptides and their receptors are intimately involved in the physiological control of systemic blood pressure and body Na homeostasis, exerting these effects through alterations in a host of circulating and local factors. Hormonal systems affected by ET include natriuretic peptides, aldosterone, catecholamines, and angiotensin. ET also directly regulates cardiac output, central and peripheral nervous system activity, renal Na and water excretion, systemic vascular resistance, and venous capacitance. ET regulation of these systems is often complex, sometimes involving opposing actions depending on which receptor isoform is activated, which cells are affected, and what other prevailing factors exist. A detailed understanding of this system is important; disordered regulation of the ET system is strongly associated with hypertension and dysregulated extracellular fluid volume homeostasis. In addition, ET receptor antagonists are being increasingly used for the treatment of a variety of diseases; while demonstrating benefit, these agents also have adverse effects on fluid retention that may substantially limit their clinical utility. This review provides a detailed analysis of how the ET system is involved in the control of blood pressure and Na homeostasis, focusing primarily on physiological regulation with some discussion of the role of the ET system in hypertension.
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Affiliation(s)
- Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA.
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8
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Plasma C-terminal pro-endothelin-1 is associated with target-organ damage in African Americans with hypertension. Am J Hypertens 2010; 23:1204-8. [PMID: 20634796 DOI: 10.1038/ajh.2010.149] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Endothelin-1 (ET-1) is a vasoactive peptide with vasoconstrictor and mitogenic properties. We investigated whether plasma levels of C-terminal pro-ET-1 (CT-proET-1), a newly described stable fragment of the ET-1 precursor, are associated with target-organ damage in hypertension. METHODS Participants included 981 African Americans (65 ± 9 years, 71% women) and 812 non-Hispanic whites (61 ± 9 years, 54% women) ascertained from sibships with hypertension. We measured plasma CT-proET-1 by an immunoluminometric assay. Measures of target-organ damage included the ankle-brachial index (ABI) and urinary albumin:creatinine ratio (UACR). Multivariable regressions analyses were employed to assess whether plasma CT-proET-1 levels were independently associated with ABI and UACR. RESULTS In hypertensive African Americans, higher plasma levels of CT-proET-1 were significantly associated with lower ABI (P < 0.01) and higher UACR (P < 0.01). After adjustment for age, sex, body mass index, systolic blood pressure (SBP) and diastolic blood pressure (BP), diabetes, serum glucose, insulin use, estimated glomerular filtration rate (eGFR), history of smoking, total and high-density lipoprotein cholesterol, medication use, and previous history of myocardial infarction (MI) or stroke, higher plasma levels of CT-proET-1 remained significantly associated with lower ABI (P < 0.01) and higher UACR (P = 0.02). In non-Hispanic white hypertensives, higher plasma levels of CT-proET-1 were weakly associated with higher UACR (P = 0.02) and with lower ABI (P = 0.07). After adjustment for the relevant covariates, no statistically significant associations between CT-proET-1 and ABI or UACR were present in whites. CONCLUSIONS Plasma levels of CT-proET-1 were independently associated with lower ABI and greater UACR in African American but not non-Hispanic white adults with hypertension.
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9
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Endothelial dysfunction in African-Americans. Int J Cardiol 2008; 132:157-72. [PMID: 19004510 DOI: 10.1016/j.ijcard.2008.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2008] [Revised: 07/25/2008] [Accepted: 10/12/2008] [Indexed: 01/13/2023]
Abstract
The journey of atherosclerosis begins with endothelial dysfunction and culminates into its most fearful destination producing ischemia, myocardial infarction and death. The excess cardiovascular disease morbidity and mortality in African-Americans is one of the major public health problems. In this review, we discuss vascular endothelial dysfunction as a key element for excess cardiovascular disease burden in this target population. It can be logical window of future atherosclerotic outcomes, and further efforts should be made to detect it at the earliest in African American individuals even if they are appearing healthy as the therapeutic interventions if instituted early, might prevent the subsequent cardiac events.
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10
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Hravnak M, Ibrahim S, Kaufer A, Sonel A, Conigliaro J. Racial disparities in outcomes following coronary artery bypass grafting. J Cardiovasc Nurs 2006; 21:367-78. [PMID: 16966914 PMCID: PMC3660098 DOI: 10.1097/00005082-200609000-00007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
More than 12 million people in the United States have coronary heart disease, the second leading cause of hospitalization in the United States. It is known that persons within racial minorities, specifically African Americans, have a higher prevalence of coronary heart disease, yet are much less likely to undergo invasive cardiac treatment interventions. An invasive intervention commonly used to treat coronary heart disease is coronary artery bypass grafting, with over 140,000 operations performed annually in the United States. However, blacks are known to experience higher post-coronary artery bypass graft morbidity and mortality. The causes for racial disparities in post-coronary artery bypass graft outcomes are not well known but may include factors related to the individual, provider, system, and society/environment, either alone or in combination. The purpose of this article is to provide an overview of the literature regarding disparities in the health and healthcare of black patients with coronary heart disease with respect to CABG, and examine potential hypotheses for variant outcomes after surgery.
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Affiliation(s)
- Marilyn Hravnak
- School of Nursing, University of Pittsburgh, Pittsburgh, Pa 15261, USA.
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11
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Abstract
Background—
Insulin resistance is strongly associated with obesity and other components of the metabolic syndrome (MS). The relative importance of these components in the determination of endothelial function is unknown. Furthermore, there is conflicting evidence about whether ethnic differences exist in the relative importance of these components in regard to other cardiovascular outcomes. We evaluated the contributions of insulin resistance, obesity, and the other components of the MS to impaired endothelial function.
Methods and Results—
The relationships of the MS components (as defined according the National Cholesterol Education Program) and insulin resistance (estimated using the homeostasis model) with endothelium-dependent vasodilation were examined in 42 white and 55 black subjects. Endothelium-dependent vasodilation was assessed as the increment in leg blood flow (measured by thermodilution) after exposure to methacholine chloride. Waist circumference, glucose, blood pressure, and insulin resistance distributions did not differ between ethnic groups; blacks in our sample had higher HDL cholesterol (1.31 versus 1.09 mmol/L;
P
<0.001) and lower triglyceride levels (1.01 versus 1.37 mmol/L;
P
=0.005) than white subjects. In the absence of the MS, black subjects exhibited reduced endothelium-dependent vasodilation compared with white subjects (
P
=0.005), and both groups demonstrated significantly worse endothelial function when the MS was present (maximal increase in leg blood flow: blacks: 107±9% MS absent, 53±16% MS present; whites: 163±16% MS absent, 54±18% MS absent;
P
=0.007, MS absent versus present;
P
=NS for interaction of ethnicity and MS). Multivariable regression analysis examining relationships of endothelial function with the 5 MS components (analyzed as continuous variables) revealed independent relationships only with waist circumference (
P
=0.01) and systolic blood pressure (
P
=0.02). Waist circumference was no longer independently associated after adding insulin resistance to the modeling (
P
=0.02 for log of homeostasis model index of insulin resistance,
P
=0.02 for systolic blood pressure). Ethnicity still exerted an independent effect on endothelial function after accounting for the above components (
P
=0.04 for an additional effect of ethnic status on endothelial function), with an ethnic difference in the effect of insulin resistance on endothelial function (
P
=0.046 for interaction of ethnicity and log of homeostasis model index of insulin resistance).
Conclusions—
These findings suggest that insulin resistance and systolic blood pressure are the principal determinants of endothelial dysfunction in the MS and that there are ethnic differences in the relative importance of these factors. These differences may imply different benefits from treatments targeting blood pressure or insulin resistance in different ethnic groups.
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Affiliation(s)
- A A Lteif
- Indiana University, Indianapolis, USA
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12
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Schiffrin EL. Vascular endothelin in hypertension. Vascul Pharmacol 2005; 43:19-29. [PMID: 15955745 DOI: 10.1016/j.vph.2005.03.004] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 01/17/2005] [Accepted: 03/01/2005] [Indexed: 12/31/2022]
Abstract
Endothelins are powerful vasoconstrictor peptides that also play numerous other functions in many different organs. Endothelin-1 (ET-1) is the most abundant and important of this family of peptides in blood vessels. Production of ET-1 is increased in the endothelium and the kidney in salt-dependent models of hypertension (e.g.: DOCA-salt rats and Dahl salt-sensitive rats, in salt-loaded SHR-SP, in angiotensin II-infused and in diabetic rats). ET-1 elicits an inflammatory response by increasing oxidant stress in the vascular wall, which induces vascular remodeling and endothelial dysfunction found in the hypertensive models that exhibit an endothelin-mediated component. Endothelin receptor antagonism reduces blood pressure and vascular hypertrophic remodeling present in these hypertensive models. Patients with stage 2 hypertension have enhanced vascular expression of ET-1. Endothelin receptor antagonists lower blood pressure in hypertensive patients. They could become therapeutic agents for prevention of target organ damage in hypertension and in type 2 diabetes, chronic renal failure and congestive heart failure. Side effects of endothelin receptor blockers have prevented up to the present their development for these indications. New endothelin antagonists devoid of these side effects, or alternatively inhibitors of the endothelin converting enzymes that generate ET-1 may in the future become available to block the endothelin system. However, to date endothelin antagonists have been approved only for the treatment of primary pulmonary hypertension, a rapidly fatal condition in which the endothelin system plays an important role and endothelin antagonists exert favorable effects.
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Affiliation(s)
- Ernesto L Schiffrin
- CIHR Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, 110 Pine Avenue West, Montreal, Quebec H2W 1R7, Canada.
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13
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Ergul A. Development of endothelin receptor antagonists as potential therapeutic agents. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.13.1.33] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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14
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Sosin MD, Bhatia GS, Davis RC, Lip GYH. Heart failure-the importance of ethnicity. Eur J Heart Fail 2004; 6:831-43. [PMID: 15556044 DOI: 10.1016/j.ejheart.2003.11.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Revised: 10/31/2003] [Accepted: 11/06/2003] [Indexed: 11/20/2022] Open
Abstract
Heart failure is a major public health problem in the Western world. Aetiological factors involved in its development include hypertension, diabetes, and ischaemic heart disease--all of which differ in prevalence, and possibly mechanism, between patients of differing ethnicity. Unfortunately, epidemiological and therapeutic trials have involved almost exclusively white populations, and evidence from these trials cannot necessarily be assumed to be generalisable to populations that include high proportions of patients from other ethnic origins. This review will discuss the mechanistic and therapeutic differences that exist in heart failure between those of European origin, and patients from the major ethnic minority groups of the UK.
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Affiliation(s)
- Michael D Sosin
- University Department of Medicine, Sandwell and West Birmingham Hospitals NHS Trust, City Hospital, Birmingham B18 7QH, England, UK
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15
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Abstract
Endothelin-1 (ET-1) is a pleiotropic hormone produced primarily by the endothelium. Synthesis of ET-1 is stimulated by the major signals of cardiovascular stress, such as vasoactive agents (angiotensin II, norepinephrine, vasopressin, and bradykinin), cytokines (e.g., tumor necrosis factor alpha and transforming growth factor beta), and other factors, including thrombin and mechanical stress. ET-1 induces vasoconstriction, is proinflammatory, promotes fibrosis, and has mitogenic potential, important factors in the regulation of vascular tone, arterial remodeling, and vascular injury. These effects are mediated via two receptor types, ETA and ETB. The role ET-1 plays in normal cardiovascular homeostasis and in mild essential hypertension in humans is unclear. However, certain groups of essential hypertensive patients may have ET-1-dependent hypertension, including blacks (subjects of African descent), salt-sensitive hypertensives, patients with low renin hypertension, and those with obesity and insulin resistance. ET-1 has also been implicated in severe hypertension, heart failure, atherosclerosis, and pulmonary hypertension. In all of these conditions, plasma immunoreactive ET levels are elevated and tissue ET-1 expression is increased. Accordingly, it is becoming increasingly apparent that ET-1 plays an important role in cardiovascular disease and in some forms of hypertension in humans. Data from clinical trials using combined ETA-ETB receptor blockers have already demonstrated significant blood-pressure-lowering effects. Thus, targeting the endothelin system may have important therapeutic potential in the treatment of hypertension, particularly by contributing to the prevention of target organ damage and the management of cardiovascular disease.
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Affiliation(s)
- Rhian M Touyz
- CIHR Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, University of Montreal, QC H2W 1R7, Canada.
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16
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Abstract
Endothelin-1 (ET-1) was first characterized as a potent vasoconstrictor and is overexpressed in the vasculature in different models of hypertension, such as deoxycorticosterone acetate-salt rats, Dahl salt-sensitive rats, and stroke-prone spontaneously hypertensive rats. Moreover, patients with moderate to severe hypertension present increased vascular levels of prepro-ET-1 mRNA. In addition to their blood pressure-lowering effects, ET receptor antagonists are able to reduce vascular growth. Recent data suggest the involvement of an inflammatory response in the effects of ET-1, which contributes to vascular remodeling and endothelial dysfunction. Increasing evidence underscores the potential therapeutic benefit of ET receptor antagonists in different hypertension-related complications, not only in essential hypertension, but also in patients with type 2 diabetes.
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Affiliation(s)
- Marc Iglarz
- Clinical Research Institute of Montreal, 110 Pine Avenue West, Quebec H2W 1R7, Canada
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17
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Schaefer BM, Caracciolo V, Frishman WH, Charney P. Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles. HEART DISEASE (HAGERSTOWN, MD.) 2003; 5:129-43. [PMID: 12713680 DOI: 10.1097/01.hdx.0000061694.62343.01] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.
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18
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Grubbs AL, Anstadt MP, Ergul A. Saphenous vein endothelin system expression and activity in African American patients. Arterioscler Thromb Vasc Biol 2002; 22:1122-7. [PMID: 12117726 DOI: 10.1161/01.atv.0000023160.67766.f0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Plasma endothelin (ET)-1 levels are significantly higher in African American hypertensive patients than in white hypertensive patients. However, whether the molecular components of vascular ET-1 biosynthesis and function are altered in this population remains to be established. Accordingly, the overall goal of this study was to investigate the effects of race on vascular mRNA and protein levels of ET-converting enzyme (ECE)-1 subisoforms, ET-1, and ET receptor profiles in hypertension. METHODS AND RESULTS Saphenous vein samples were obtained from African American (n=13) and white (n=15) patients undergoing coronary artery grafting surgery. The expression of preproET-1 and of ECE-1a was upregulated approximately 2- and 3-fold, respectively, in African Americans. In endothelium-intact vessels, the ET(A) expression was higher in whites. In endothelium-denuded vessels, the ET(B) mRNA was 3-fold higher in African Americans, suggesting that vasoconstriction-promoting ET(B) receptors are upregulated in this population. Vascular tissue ET-1 levels and ECE-1 activity were also augmented in African American patients. CONCLUSIONS This study demonstrated that the biosynthetic pathway of ET-1 is activated to a higher degree and that the ET(B) receptor subtype expression is altered in the peripheral vasculature of African American hypertensive patients. The augmented synthesis and altered expression of ET(B) receptors may both contribute to the increased incidence of hypertension and related complications in this patient population.
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Affiliation(s)
- Ashley L Grubbs
- Department of Surgery, Medical University of South Carolina, Charleston, USA
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19
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Ergul A. Endothelin-1 and endothelin receptor antagonists as potential cardiovascular therapeutic agents. Pharmacotherapy 2002; 22:54-65. [PMID: 11794430 DOI: 10.1592/phco.22.1.54.33505] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Endothelin (ET)-1 is an endothelium-derived peptide with potent vasoconstrictor and proliferative properties. The ET system is activated in several cardiovascular disease states associated with functional and structural vascular changes, including hypertension and heart failure. The two ET receptor subtypes are known as ET(A)R and ET(B)R. The former is located mainly on vascular smooth muscle cells and is responsible for mediating vasoconstriction and proliferation. The latter is present predominantly on endothelial cells and mediates vasorelaxation as well as ET-1 clearance. Activation of smooth muscle ET(B)R causes vasoconstriction. Selective ET(A)R antagonists as well as nonselective ET(A)R-ET(B)R antagonists have been developed. Studies with animal models and early-phase clinical trials provided strong evidence that these agents are effective in the treatment of heart failure, essential hypertension, pulmonary hypertension, and atherosclerosis. However, the complexity of biologic effects mediated by two different receptor subtypes complicates therapy with selective versus nonselective ET receptor antagonists. In addition to subtype selectivity and potency, changes in receptor subtype distribution under different pathologic conditions and different patient populations will play a crucial role in the evaluation of these potentially therapeutic drugs.
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Affiliation(s)
- Adviye Ergul
- Department of Clinical and Administrative Sciences, University of Georgia College of Pharmacy, Athens, USA.
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20
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Clark LT, Ferdinand KC, Flack JM, Gavin JR, Hall WD, Kumanyika SK, Reed JW, Saunders E, Valantine HA, Watson K, Wenger NK, Wright JT. Coronary heart disease in African Americans. HEART DISEASE (HAGERSTOWN, MD.) 2001; 3:97-108. [PMID: 11975778 DOI: 10.1097/00132580-200103000-00007] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
African Americans have the highest overall mortality rate from coronary heart disease (CHD) of any ethnic group in the United States, particularly out-of-hospital deaths, and especially at younger ages. Although all of the reasons for the excess CHD mortality among African Americans have not been elucidated, it is clear that there is a high prevalence of certain coronary risk factors, delay in the recognition and treatment of high-risk individuals, and limited access to cardiovascular care. The clinical spectrum of acute and chronic CHD in African Americans is similar to that in whites. However, African Americans have a higher risk of sudden cardiac death and present more often with unstable angina and non-Q-wave myocardial infarction than whites. African Americans have less obstructive coronary artery disease on angiography, but may have a similar or greater total burden of coronary atherosclerosis. Ethnic differences in the clinical manifestations of CHD may be explained largely by the inherent heterogeneity of the coronary syndromes, and the disproportionately high prevalence and severity of hypertension and type 2 diabetes in African Americans. Identification of high-risk individuals for vigorous risk factor modification-especially control of hypertension, regression of left ventricular hypertrophy, control of diabetes, treatment of dyslipidemia, and smoking cessation--is key for successful risk reduction.
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Affiliation(s)
- L T Clark
- Division of Cardiovascular Medicine, State University of New York Health Science Center, Brooklyn, New York, USA
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21
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Ergul A. Hypertension in black patients: an emerging role of the endothelin system in salt-sensitive hypertension. Hypertension 2000; 36:62-7. [PMID: 10904013 DOI: 10.1161/01.hyp.36.1.62] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The prevalence of essential hypertension in blacks is much higher than that in whites. In addition, the pathogenesis of hypertension appears to be different in black patients. For example, black patients present with a salt-sensitive hypertension characterized by low renin levels. Racial differences in renal physiology and socioeconomic factors have been suggested as possible causes of this difference, but reasons for this difference remain unclear. Endothelial cells are important in the regulation of vascular tonus and homeostasis, in part through the secretion of vasoactive substances. One of these factors, endothelin-1 (ET-1), is a 21 amino acid residue peptide with potent vasopressor actions. In addition to its contractile effects, it has been shown to stimulate mitogenesis in a number of cell types. Moreover, ET-1 displays modulatory effects on the endocrine system, including stimulation of angiotensin II and aldosterone production and inhibition of antidiuretic hormone in the kidney. Recent data from several laboratories indicate that ET-1 is overexpressed in the vasculature in several salt-sensitive models of experimental hypertension. Moreover, circulating plasma ET-1 levels are significantly increased in black hypertensives compared with white hypertensives. Thus, the ET system might be particularly important in the development or maintenance of hypertension in this population.
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Affiliation(s)
- A Ergul
- Department of Surgery, Medical University of South Carolina, Charleston 29425, USA.
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Treiber FA, Jackson RW, Davis H, Pollock JS, Kapuku G, Mensah GA, Pollock DM. Racial differences in endothelin-1 at rest and in response to acute stress in adolescent males. Hypertension 2000; 35:722-5. [PMID: 10720585 DOI: 10.1161/01.hyp.35.3.722] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Blacks exhibit greater vasoconstriction-mediated blood pressure (BP) increases in response to stress than do whites. Endothelin-1 (ET-1), a potent vasoconstrictive peptide, has been proposed as having a role in racial differences in stress reactivity. We evaluated the hemodynamic and plasma ET-1 levels of 41 (23 whites, 18 blacks, mean age 18.6 years) normotensive adolescent males at rest and in response to a video game challenge and forehead cold stimulation. Measurements were performed at catheter insertion and before and immediately after the 2 stressors, which were separated by 20-minute rest periods. Blacks exhibited higher absolute levels of diastolic blood pressure, total peripheral resistance index, or both in response to catheter insertion and to the video game challenge and during recovery from video game challenge and cold stimulation (P<0. 05 for all). Blacks exhibited higher absolute levels of ET-1 at every evaluation point (P<0.05 for all) and greater increases in ET-1 in response to both stressors (ps<0.05). These findings suggest that altered endothelial function may be involved in racial differences in hemodynamic reactivity to stress and possibly in the development of essential hypertension.
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Affiliation(s)
- F A Treiber
- Georgia Prevention Institute, the Vascular Biology Center, Departments of Pediatrics and Psychiatry , and Office of Biostatistics, Medical College of Georgia, Augusta, GA 30912-3710, USA.
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