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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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Turner CG, Hayat MJ, Grosch C, Quyyumi AA, Otis JS, Wong BJ. Endothelin A receptor inhibition increases nitric oxide-dependent vasodilation independent of superoxide in non-Hispanic Black young adults. J Appl Physiol (1985) 2023; 134:891-899. [PMID: 36892887 PMCID: PMC10042601 DOI: 10.1152/japplphysiol.00739.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023] Open
Abstract
Young non-Hispanic Black adults have reduced microvascular endothelial function compared with non-Hispanic White counterparts, but the mechanisms are not fully elucidated. The purpose of this study was to investigate the effect of endothelin-1 A receptor (ETAR) and superoxide on cutaneous microvascular function in young non-Hispanic Black (n = 10) and White (n = 10) adults. Participants were instrumented with four intradermal microdialysis fibers: 1) lactated Ringer's (control), 2) 500 nM BQ-123 (ETAR antagonist), 3) 10 μM tempol (superoxide dismutase mimetic), and 4) BQ-123 + tempol. Skin blood flow was assessed via laser-Doppler flowmetry (LDF), and each site underwent rapid local heating from 33°C to 39°C. At the plateau of local heating, 20 mM l-NAME [nitric oxide (NO) synthase inhibitor] was infused to quantify NO-dependent vasodilation. Data are means ± standard deviation. NO-dependent vasodilation was decreased in non-Hispanic Black compared with non-Hispanic White young adults (P < 0.01). NO-dependent vasodilation was increased at BQ-123 sites (73 ± 10% NO) and at BQ-123 + tempol sites (71 ± 10%NO) in non-Hispanic Black young adults compared with control (53 ± 13%NO, P = 0.01). Tempol alone had no effect on NO-dependent vasodilation in non-Hispanic Black young adults (63 ± 14%NO, P = 0.18). NO-dependent vasodilation at BQ-123 sites was not statistically different between non-Hispanic Black and White (80 ± 7%NO) young adults (P = 0.15). ETAR contributes to reduced NO-dependent vasodilation in non-Hispanic Black young adults independent of superoxide, suggesting a greater effect on NO synthesis rather than NO scavenging via superoxide.NEW & NOTEWORTHY Endothelin-1 A receptors (ETARs) have been shown to reduce endothelial function independently and through increased production of superoxide. We show that independent ETAR inhibition increases microvascular endothelial function in non-Hispanic Black young adults. However, administration of a superoxide dismutase mimetic alone and in combination with ETAR inhibition had no effect on microvascular endothelial function suggesting that, in the cutaneous microvasculature, the negative effects of ETAR in non-Hispanic Black young adults are independent of superoxide production.
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Affiliation(s)
- Casey G Turner
- Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia, United States
| | - Matthew J Hayat
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, Georgia, United States
| | - Caroline Grosch
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, Georgia, United States
| | - Arshed A Quyyumi
- Emory Clinical Cardiovascular Research Institute, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Jeffrey S Otis
- Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia, United States
| | - Brett J Wong
- Department of Kinesiology and Health, Georgia State University, Atlanta, Georgia, United States
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Kidney Function and Aortic Stiffness, Pulsatility, and Endothelial Function in African Americans: The Jackson Heart Study. Kidney Med 2021; 3:702-711.e1. [PMID: 34693252 PMCID: PMC8515070 DOI: 10.1016/j.xkme.2021.03.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Rationale & Objective The relation of vascular stiffness, endothelial function, and kidney function is incompletely elucidated in African Americans. Our hypothesis was that increased vascular stiffness and endothelial dysfunction are associated with low estimated glomerular filtration rate (eGFR) and albuminuria in African Americans. Study Design Cross-sectional cohort analysis of data from the Jackson Heart Study. Settings & Patients 2,244 Jackson Heart Study participants (2012-2017 after Exam 3) who had undergone noninvasive hemodynamic assessment using arterial tonometry. Predictors Baseline carotid-femoral pulse wave velocity, pulsatile hemodynamics forward wave amplitude, and hyperemic brachial artery flow were measured. Reduced eGFR was defined as eGFR between 15 and 60 mL/min/1.73 m2. Outcomes Prevalent albuminuria, urinary albumin-creatinine ratio. Analytical Approach 2-sample t test for continuous variables and χ2 test for categorical variables in addition to logistic and linear regression models to assess the risk for chronic kidney disease with each proposed hemodynamic variable. Results Among 2,244 participants, mean age was 66 ± 11 years and 64% were women. Reduced eGFR was present in 233 (10.4%), and elevated urinary albumin-creatinine ratio, in 232 (10.4%). In multivariable-adjusted analyses, higher carotid-femoral pulse wave velocity was associated with the presence of reduced eGFR (OR, 1.37 [95% CI, 1.08-1.75] per SD; P = 0.01) and with prevalent albuminuria (OR, 1.66 [95% CI, 1.32-2.11]; P < 0.001). Higher forward wave amplitude was significantly associated with prevalent albuminuria (OR, 1.37 [95% CI, 1.14-1.65]; P = 0.001). Limitations Cross-sectional analyses cannot inform causality. Conclusions Higher arterial stiffness and pulsatility are associated with higher odds of reduced eGFR in African Americans. Future studies should focus on whether improving arterial stiffness contributes to kidney protection in African Americans.
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Jeong JH, Brown ML, Kapuku G, Harshfield GA, Park J. α-Adrenergic receptor blockade attenuates pressor response during mental stress in young black adults. Physiol Rep 2021; 8:e14642. [PMID: 33356011 PMCID: PMC7757373 DOI: 10.14814/phy2.14642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022] Open
Abstract
Black individuals exhibit increased blood pressure (BP) responses to sympathetic stimulation that are associated with an increased risk of hypertension (HTN). We tested the hypothesis that α1 -adrenergic blockade inhibits the increased BP response during and after 45-min stress in young normotensive Black adults, which may be mediated, in part, by dampened vasoconstriction and decreased renal sodium retention. Utilizing a double-masked randomized, crossover study design, 51 normotensive Black adults (31 ± 8 yr) were treated with either a placebo or 1 mg/day of prazosin for 1 week. On the final day of each treatment, hemodynamic measures and urinary sodium excretion (UNaV) were collected before (Rest), during (Stress) and after (Recovery) 45 min of mental stress induced via a competitive video game task. During the Stress period, diastolic BP and total peripheral resistance (TPR) were significantly lower with prazosin compared to placebo (p < .05 for both). Similarly, we observed lower systolic BP, diastolic BP, and TPR during the Recovery period with prazosin versus placebo (p < .05 for both). There was no effect of prazosin on stress-associated UNaV. The change in systolic BP from Rest to Recovery was positively associated with the change in TPR with both treatments (p < .05 for both). In summary, prazosin treatment dampened BP reactivity to 45-min mental stress and lowered post-stress BP over the recovery period, which was linked to reduce TPR in young normotensive Black adults. These results suggest that α1 -adrenergic receptor activity may contribute to BP responses and delayed BP recovery to prolonged mental stress through increased vasoconstriction in Black adults.
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Affiliation(s)
- Jin Hee Jeong
- Department of MedicineGeorgia Prevention InstituteMedical College of GeorgiaAugusta UniversityAugustaGAUSA
- Division of Renal MedicineDepartment of MedicineEmory UniversityAtlantaGAUSA
- Department of Veterans Affairs Health Care SystemDecaturGAUSA
| | - Michelle L. Brown
- Department of MedicineGeorgia Prevention InstituteMedical College of GeorgiaAugusta UniversityAugustaGAUSA
| | - Gaston Kapuku
- Department of MedicineGeorgia Prevention InstituteMedical College of GeorgiaAugusta UniversityAugustaGAUSA
| | - Gregory A. Harshfield
- Department of MedicineGeorgia Prevention InstituteMedical College of GeorgiaAugusta UniversityAugustaGAUSA
| | - Jeanie Park
- Division of Renal MedicineDepartment of MedicineEmory UniversityAtlantaGAUSA
- Department of Veterans Affairs Health Care SystemDecaturGAUSA
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Hartwig CL, Sprick JD, Jeong J, Hu Y, Morison DG, Stein CM, Paranjape S, Park J. Increased vascular α1-adrenergic receptor sensitivity in older adults with posttraumatic stress disorder. Am J Physiol Regul Integr Comp Physiol 2020; 319:R611-R616. [PMID: 32966119 DOI: 10.1152/ajpregu.00155.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Posttraumatic stress disorder (PTSD) is an independent risk factor for the development of hypertension and cardiovascular disease. Patients with PTSD have heightened blood pressure and sympathetic nervous system reactivity; however, it is unclear if patients with PTSD have exaggerated vasoconstriction in response to sympathetic nerve activation that could also contribute to increased blood pressure reactivity. Therefore, we hypothesized that patients with PTSD have increased sensitivity of vascular α1-adrenergic receptors (α1ARs), the major mediators of vasoconstriction in response to release of norepinephrine at sympathetic nerve terminals. To assess vascular α1AR sensitivity, we measured the degree of venoconstriction in a dorsal hand vein in response to exponentially increasing doses of the selective α1AR agonist, phenylephrine (PE), in 9 patients with PTSD (age = 59 ± 2 yr) and 10 age-matched controls (age = 60 ± 1 yr). Individual dose-response curves were generated to determine the dose of PE that induces 50% of maximal venoconstriction (i.e., PE ED50) reflective of vascular α1AR sensitivity. In support of our hypothesis, PE ED50 values were lower in PTSD compared with controls (245 ± 54 ng/min vs. 1,995 ± 459 ng/min, P = 0.012), indicating increased vascular α1AR sensitivity in PTSD. The PTSD group also had an increase in slope of rise in venoconstriction, indicative of an altered venoconstrictive reactivity to PE compared with controls (19.8% ± 1.2% vs. 15.1% ± 1.2%, P = 0.009). Heightened vascular α1AR sensitivity in PTSD may contribute to augmented vasoconstriction and blood pressure reactivity to sympathoexcitation and to increased cardiovascular disease risk in this patient population.
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Affiliation(s)
- Cortnie L Hartwig
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - Justin D Sprick
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - Jinhee Jeong
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - Yingtian Hu
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Doree G Morison
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - C Michael Stein
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Sachin Paranjape
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jeanie Park
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
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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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7
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Farrell MC, Giza RJ, Shibao CA. Race and sex differences in cardiovascular autonomic regulation. Clin Auton Res 2020; 30:371-379. [PMID: 32894376 DOI: 10.1007/s10286-020-00723-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/19/2020] [Indexed: 12/17/2022]
Abstract
Racial and ethnic differences in cardiovascular morbidity and mortality persist despite advances in risk factor identification and implementation of evidence-based treatment strategies. African American men and women are disproportionately affected by cardiovascular risk factors, particularly hypertension. In this context, previous studies have identified sex and racial differences in autonomic cardiovascular regulation which may contribute to the development of hypertension and its high morbidity burden among African Americans. In this review, we provide a comprehensive evaluation of the potential pathophysiological mechanisms of blood pressure control and their differences based on sex and race. These mechanisms include obesity-induced sympathetic activation, sympatho-vascular transduction, baroreflex sensitivity and adrenoreceptor vascular sensitivity, which have been the subjects of prior investigation in this field. Understanding the racial differences in the pathophysiology of hypertension and its co-morbid conditions would allow us to implement better treatment strategies tailored to African Americans, with the ultimate goal of reducing cardiovascular mortality in this population.
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Affiliation(s)
| | - Richard J Giza
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Cyndya A Shibao
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University Medical Center, 506 Robinson Research Building, Nashville, TN, 37232-6602, USA.
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8
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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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Sprick JD, Morison DL, Stein CM, Li Y, Paranjape S, Fonkoue IT, DaCosta DR, Park J. Vascular α 1-adrenergic sensitivity is enhanced in chronic kidney disease. Am J Physiol Regul Integr Comp Physiol 2019; 317:R485-R490. [PMID: 31314543 DOI: 10.1152/ajpregu.00090.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chronic kidney disease (CKD) is often complicated by difficult-to-control hypertension, in part due to chronic overactivation of the sympathetic nervous system (SNS). CKD patients also exhibit a greater increase in arterial blood pressure for a given increase in sympathetic nerve activation, suggesting an augmented vasoconstrictive response to SNS activation (i.e., neurovascular transduction). One potential mechanism of increased sympathetic neurovascular transduction is heightened sensitivity of the vascular α1-adrenergic receptors (α1ARs), the major effectors of vasoconstriction in response to norepinephrine release at the sympathetic nerve terminals. Therefore, we hypothesized that patients with CKD have increased vascular α1AR sensitivity. We studied 32 patients with CKD stages III and IV (age 59.9 ± 1.3 yr) and 19 age-matched controls (CON, age 63.2 ± 1.6 yr). Using a linear variable differential transformer (LVDT), we measured change in venoconstriction in response to exponentially increasing doses of the selective α1AR agonist phenylephrine (PE) administered sequentially into a dorsal hand vein. Individual semilogarithmic PE dose-response curves were constructed for each participant to determine the PE dose at which 50% of maximum venoconstriction occurred (ED50), reflecting α1AR sensitivity. In support of our hypothesis, CKD patients had a lower PE ED50 than CON (CKD = 2.23 ± 0.11 vs. CON = 2.63 ± 0.20, P = 0.023), demonstrating increased vascular α1AR sensitivity. Additionally, CKD patients had a greater venoconstrictive capacity to PE than CON (P = 0.015). Augmented α1AR sensitivity may contribute mechanistically to enhanced neurovascular transduction in CKD and may explain, in part, the greater blood pressure reactivity exhibited in these patients.
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Affiliation(s)
- Justin D Sprick
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - Doree L Morison
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - C Michael Stein
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yunxiao Li
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Sachin Paranjape
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Ida T Fonkoue
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - Dana R DaCosta
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
| | - Jeanie Park
- Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia.,Department of Veterans Affairs Health Care System, Decatur, Georgia
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Covassin N, Greene EL, Singh P, Somers VK. Disparities in Hypertension Among African-Americans: Implications of Insufficient Sleep. Curr Hypertens Rep 2018; 20:57. [PMID: 29884924 DOI: 10.1007/s11906-018-0855-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Sleep deficiency has been proposed as a potential contributor to racial disparities in cardiovascular health. We present contemporary evidence on the unequal burden of insufficient sleep in Blacks/African-Americans and the repercussions for disparate risk of hypertension. RECENT FINDINGS The prevalence of insufficient sleep is high and rising and has been recognized as an important cardiovascular risk factor. Presumably due to a constellation of environmental, psychosocial, and individual determinants, these risks appear exacerbated in Blacks/African-Americans, who are more likely to experience short sleep than other ethnic/racial groups. Population-based data suggest that the risk of hypertension associated with sleep deficiency is greater in those of African ancestry. However, there is a paucity of experimental evidence linking short sleep duration to blood pressure levels in African-Americans. Blacks/African-Americans may be more vulnerable to sleep deficiency and to its hypertensive effects. Future research is needed to unequivocally establish causality and determine the mechanism underlying the postulated racial inequalities in sleep adequacy and consequent cardiovascular risk.
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Affiliation(s)
- Naima Covassin
- Department of Cardiovascular Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Eddie L Greene
- Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Prachi Singh
- Department of Cardiovascular Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN, 55905, USA
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN, 55905, USA
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Malan L, Hamer M, von Känel R, Lambert GW, Delport R, Steyn HS, Malan NT. Chronic defensiveness and neuroendocrine dysfunction reflect a novel cardiac troponin T cut point: The SABPA study. Psychoneuroendocrinology 2017; 85:20-27. [PMID: 28787643 DOI: 10.1016/j.psyneuen.2017.07.492] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 07/14/2017] [Accepted: 07/26/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND Sympatho-adrenal responses are activated as an innate defense coping (DefS) mechanism during emotional stress. Whether these sympatho-adrenal responses drive cardiac troponin T (cTnT) increases are unknown. Therefore, associations between cTnT and sympatho-adrenal responses were assessed. METHODS A prospective bi-ethnic cohort, excluding atrial fibrillation, myocardial infarction and stroke cases, was followed for 3 years (N=342; 45.6±9.0years). We obtained serum high-sensitive cTnT and exposure measures [Coping-Strategy-Indicator, depression/Patient-Health-Questionnarie-9, 24h BP, 24h heart-rate-variability (HRV) and 24h urinary catecholamines]. RESULTS Blacks showed moderate depression (45% vs. 16%) and 24h hypertension (67% vs. 42%) prevalence compared to Whites. A receiver-operating-characteristics cTnT cut-point 4.2ng/L predicting hypertension in Blacks was used as binary outcome measure in relation to exposure measures [AUC 0.68 (95% CI 0.60-0.76); sensitivity/specificity 63/70%; P≤0.001]. Bi-ethnic cTnT-incidence was similar (Blacks=27%, Whites=25%) with cTnT-recovery better in Blacks (9%) compared to Whites (5%), P=0.001. In cross-sectional analyses, elevated cTnT was related to DefS [OR 1.08 (95% CI 0.99-1.16); P=0.06]; 24h BP [OR 1.03-1.04 (95% CI 1.01-1.08); P≤0.02] and depressed HRV [OR 2.19 (95% CI 1.09-4.41); P=0.03] in Blacks, but not in Whites. At 3year follow-up, elevated cTnT was related to attenuated urine norepinephrine:creatinine ratio in Blacks [OR 1.46 (95% CI 1.01-2.10); P=0.04]. In Whites, a cut point of 5.6ng/L cTnT predicting hypertension was not associated with exposure measures. CONCLUSION Central neural control systems exemplified a brain-heart stress pathway. Desensitization of sympatho-adrenal responses occurred with initial neural- (HRV) followed by neuroendocrine dysfunction (norepinephrine:creatinine) in relation to elevated cTnT. Chronic defensiveness may thus drive the desensitization or physiological depression, reflecting ischemic heart disease risk at a novel 4.2ng/L cTnT cut-point in Blacks.
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Affiliation(s)
- Leoné Malan
- Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
| | - Mark Hamer
- Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa; National Centre for Sport and Exercise Medicine, Loughborough University, Leicestershire, United Kingdom
| | - Roland von Känel
- Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa; Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Gavin W Lambert
- Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Australia; Baker Heart & Diabetes Institute, Melbourne, Australia
| | - Rhena Delport
- Department of Chemical Pathology, University of Pretoria, South Africa
| | - Hendrik S Steyn
- Statistical Consultation Services, North-West University, Potchefstroom, South Africa
| | - Nicolaas T Malan
- Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa
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12
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Hill LK, Sherwood A, Blumenthal JA, Hinderliter AL. Hemodynamics and Vascular Hypertrophy in African Americans and Caucasians With High Blood Pressure. Am J Hypertens 2016; 29:1380-1385. [PMID: 27481880 DOI: 10.1093/ajh/hpw080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/06/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Hypertension in African Americans is characterized by greater systemic vascular resistance (SVR) compared with Caucasian Americans, but the responsible mechanisms are not known. The present study sought to determine if peripheral vascular hypertrophy is a potential mechanism contributing to elevated SVR in African Americans with high blood pressure (BP). METHODS In a biracial sample of 80 men and women between the ages of 25 and 45 years, with clinic BP in the range 130/85-160/99mm Hg, we assessed cardiac output and SVR, in addition to BP. Minimum forearm vascular resistance (MFVR), a marker of vascular hypertrophy, also was assessed. RESULTS SVR was elevated in African Americans compared with Caucasians (P < 0.001). Regression models indicated that age, body mass index, 24-hour diastolic BP, and ethnicity were significant predictors of SVR. There was also a significant interaction between ethnicity and MFVR in explaining SVR in the study sample. In particular, there was a significant positive association between MFVR and SVR among African Americans (P = 0.002), whereas the association was inverse and not statistically significant among Caucasians (P = 0.601). CONCLUSION Hypertrophy of the systemic microvasculature may contribute to the elevated SVR that is characteristic of the early stages of hypertension in African American compared with Caucasians.
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Genetic variation in the alpha 1B-adrenergic receptor and vascular response. THE PHARMACOGENOMICS JOURNAL 2016; 17:366-371. [PMID: 27089938 PMCID: PMC5071105 DOI: 10.1038/tpj.2016.29] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/04/2016] [Accepted: 02/26/2016] [Indexed: 12/26/2022]
Abstract
α1B- adrenergic receptors contribute to vasoconstriction in humans. We tested the hypothesis that variation in the ADRA1B gene contributes to interindividual variability and ethnic differences in adrenergic vasoconstriction. We measured dorsal hand vein responses to increasing doses of phenylephrine in 64 Caucasians and 41 African-Americans and genotyped 34 ADRA1B variants. We validated findings in another model of catecholamine-induced vasoconstriction, the increase in mean arterial pressure (ΔMAP) during a cold pressor test (CPT). One ADRA1B variant, rs10070745, present in 14 African-American heterozygotes but not in Caucasians, was associated with a lower phenylephrine ED50 (geometric mean [95% CI], 144 [69–299] ng/ml) compared to 27 African-American non-carriers (208 [130–334] ng/ml; P=0.015) and contributed to the ethnic differences in ED50. The same variant was also associated with a greater ΔMAP during CPT (P=0.008). In conclusion, ADRA1B rs10070745 was significantly associated with vasoconstrictor responses after adrenergic stimulation and contributed to the ethnic difference in phenylephrine sensitivity.
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14
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Okada Y, Jarvis SS, Best SA, Edwards JG, Hendrix JM, Adams-Huet B, Vongpatanasin W, Levine BD, Fu Q. Sympathetic Neural and Hemodynamic Responses During Cold Pressor Test in Elderly Blacks and Whites. Hypertension 2016; 67:951-8. [PMID: 27021009 DOI: 10.1161/hypertensionaha.115.06700] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Accepted: 03/01/2016] [Indexed: 11/16/2022]
Abstract
The sympathetic response during the cold pressor test (CPT) has been reported to be greater in young blacks than whites, especially in those with a family history of hypertension. Because blood pressure (BP) increases with age, we evaluated whether elderly blacks have greater sympathetic activation during CPT than age-matched whites. BP, heart rate, cardiac output, and muscle sympathetic nerve activity were measured during supine baseline, 2-minute CPT, and 3-minute recovery in 47 elderly (68 ± 7 [SD] years) volunteers (12 blacks and 35 whites). Baseline BP, heart rate, cardiac output, or muscle sympathetic nerve activity did not differ between races. Systolic and diastolic BP and heart rate increased during CPT (all P<0.001) with no racial differences (all P > 0.05). Cardiac output increased during CPT and ≤ 30 s of recovery in both groups, but was lower in blacks than whites. Muscle sympathetic nerve activity increased during CPT in both groups (both P<0.001); the increase in burst frequency was similar between groups, whereas the increase in total activity was smaller in blacks (P=0.030 for interaction). Peak change (Δ) in diastolic BP was correlated with Δ total activity at 1 minute into CPT in both blacks (r=0.78,P=0.003) and whites (r=0.43,P=0.009), whereas the slope was significantly greater in blacks (P=0.007). Thus, elderly blacks have smaller sympathetic and central hemodynamic (eg, cardiac output) responses, but a greater pressor response for a given sympathetic activation during CPT than elderly whites. This response may stem from augmented sympathetic vascular transduction, greater sympathetic activation to other vascular bed(s), or enhanced nonadrenergically mediated vasoconstriction in elderly blacks.
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Affiliation(s)
- Yoshiyuki Okada
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Sara S Jarvis
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Stuart A Best
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Jeffrey G Edwards
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Joseph M Hendrix
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Beverley Adams-Huet
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Wanpen Vongpatanasin
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Benjamin D Levine
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.)
| | - Qi Fu
- From the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas (Y.O., S.S.J., S.A.B., J.G.E., B.D.L., Q.F.); Departments of Internal Medicine (Y.O., S.S.J., S.A.B., B.A.-H., W.V., B.D.L., Q.F.) and Anesthesiology and Pain (J.M.H.), UT Southwestern Medical Center, Dallas, TX; Department of Special Care Dentistry, Matsumoto Dental University, Nagano, Japan (Y.O.); and Department of Biological Sciences, Northern Arizona University, Flagstaff (S.S.J.).
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15
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Yano Y, Ning H, Muntner P, Reis JP, Calhoun DA, Viera AJ, Levine DA, Jacobs DR, Shimbo D, Liu K, Greenland P, Lloyd-Jones D. Nocturnal Blood Pressure in Young Adults and Cognitive Function in Midlife: The Coronary Artery Risk Development in Young Adults (CARDIA) Study. Am J Hypertens 2015; 28:1240-7. [PMID: 25783740 PMCID: PMC4580541 DOI: 10.1093/ajh/hpv028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 02/02/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Nocturnal blood pressure (BP) is associated with risk for cardiovascular events. However, the relationship between nocturnal BP in young adults and cognitive function in midlife remains unclear. METHODS We used data from the ambulatory BP monitoring substudy of the Coronary Artery Risk Development in Young Adults Study, including 224 participants (mean age 30 years, 45% men, 63% African Americans). At the 20-year follow-up, the Stroop test (executive function), Digit Symbol Substitution Test (psychomotor speed), and Rey Auditory Verbal Learning Test (verbal memory) were assessed. RESULTS Baseline mean office, daytime, and nocturnal BP were 109/73, 120/74, and 107/59 mm Hg, respectively. Nocturnal BP dipping, calculated as (nocturnal systolic BP [SBP]--daytime SBP) × 100/daytime SBP, was divided into quartiles (Q1: -39.3% to -16.9%; Q2: -16.8% to -13.2%, Q3 [reference]: -13.1% to -7.8%, and Q4: -7.7% to +56.4%). In multiple regression analyses, the least nocturnal SBP dipping (Q4 vs. reference) and higher nocturnal diastolic BP level were associated with worse Stroop scores, with adjustments for demographic and clinical characteristics, and cumulative exposure to office BP during follow-up (β [standard error]: 0.37 [0.18] and 0.19 [0.07], respectively; all P < 0.05). Digit Symbol Substitution Test and Rey Auditory Verbal Learning Test were not significantly associated with nocturnal SBP dipping or nocturnal SBP/diastolic BP levels. CONCLUSIONS Among healthy young adults, less nocturnal SBP dipping and higher nocturnal diastolic BP levels were associated with lower executive function in midlife, independent of multiple measures of office BP during long-term follow-up.
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Affiliation(s)
- Yuichiro Yano
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA;
| | - Hongyan Ning
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Paul Muntner
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alaska, USA
| | - Jared P Reis
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA
| | - David A Calhoun
- Vascular Biology and Hypertension Program, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alaska, USA
| | - Anthony J Viera
- Hypertension Research Program and Department of Family Medicine, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Deborah A Levine
- Departments of Internal Medicine and Neurology and Stroke Program, University of Michigan Health System, Veterans Affairs Health Services Research and Development Center of Excellence, Ann Arbor, Michigan, USA
| | - David R Jacobs
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, USA
| | - Daichi Shimbo
- Department of Medicine, Center for Behavioral Cardiovascular Health, Columbia University, New York, USA
| | - Kiang Liu
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Philip Greenland
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Donald Lloyd-Jones
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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16
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Rodriguez F, Ferdinand KC. Hypertension in minority populations: new guidelines and emerging concepts. Adv Chronic Kidney Dis 2015; 22:145-53. [PMID: 25704352 DOI: 10.1053/j.ackd.2014.08.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/12/2014] [Accepted: 08/13/2014] [Indexed: 12/15/2022]
Abstract
Persistent disparities in hypertension, CKD, and associated cardiovascular disease have been noted in the United States among racial/ethnic minority groups. Overall, these disparities are largely mediated by social determinants of health. Yet, emerging data suggest additional biologic factors in racial/ethnic disparities in hypertension prevalence, complications, particularly CKD, and responses to treatment. Nevertheless, race is a social construct and not a physiologic concept, and ethnicity, federally defined as the binary "Hispanic/Latino" or "not Hispanic/Latino," is also imprecise. However, race/ethnicity categories may help interpret health-related data, including surveillance and research, and are important in ensuring that clinical trials remain generalizable to diverse populations. There is significant heterogeneity among prespecified groups and, perhaps, greater genetic differences within than between certain racial/ethnic groups. This review will explore hypertension epidemiology, pathophysiology, and management among the diverse and growing US minority groups, specifically African Americans and Hispanics because much less data are available across the wide spectrum of diverse populations. We will highlight the intersection of hypertension and increasingly prevalent CKD, particularly in African Americans. Finally, we propose multidimensional treatment approaches to hypertension among diverse populations, encompassing population, community, health system, and individual-based approaches.
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17
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Genetic variation in the α1A-adrenergic receptor and phenylephrine-mediated venoconstriction. THE PHARMACOGENOMICS JOURNAL 2014; 15:310-5. [PMID: 25421140 PMCID: PMC4442768 DOI: 10.1038/tpj.2014.69] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 08/08/2014] [Accepted: 09/19/2014] [Indexed: 11/12/2022]
Abstract
There is large interindividual variability and ethnic differences in phenylephrine-mediated vasoconstriction. We tested the hypothesis that genetic variation in ADRA1A, the α1A adrenergic receptor gene, contributes to the variability and ethnic differences. We measured local dorsal hand vein responses to increasing doses of phenylephrine in 64 Caucasians and 42 African-Americans and genotyped for 32 ADRA1A SNPs. The ED50 ranged from 11 to 5442 ng/min, and the Emax ranged from 13.5% to 100%. The rs574647 variant was associated with a trend towards lower logED50 in each race and in the combined cohort (P=0.008). Additionally, rs1079078 was associated with a trend to higher logED50 in each race and in the combined cohort (P=0.011). Neither variant accounted for the ethnic differences in response. None of the ADRA1A haplotypes was associated with the outcomes. In conclusion, ADRA1A variants do not contribute substantially to the marked interindividual variability or ethnic differences in phenylephrine-mediated venoconstriction.
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18
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Ivanov AY, Petrov AE, Vershinina EA, Galagudza MM, Vlasov TD. Evidence of active regulation of cerebral venous tone in individuals undergoing embolization of brain arteriovenous malformations. J Appl Physiol (1985) 2013; 115:1666-71. [PMID: 24114702 DOI: 10.1152/japplphysiol.00951.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebral venous drainage is generally believed to be regulated primarily by hydrodynamic forces. To gain further insight into the regulation of this process, we investigated the response of blood flow velocity and cross-sectional area (CSA) of the internal jugular veins (IJVs) to local hemodynamic shifts. All procedures and assessments were performed on patients (n = 30) undergoing embolization of brain arteriovenous malformations (AVMs). The procedure efficiency was verified by the postembolization reduction in time-averaged maximum blood flow velocities, as well as the elevation of pulsatility index and resistance index in the arterial feeders. In cerebral veins, the dominant IJV pressure remained unchanged during the procedure. At the same time, AVM embolization caused a significant reduction in maximal CSA (84 ± 7.6 to 68 ± 7.7 mm(2), P < 0.05) and minimal CSA (68 ± 7.0 to 51 ± 7.0 mm(2), P < 0.01) of the IJV located ipsilateral to the AVM, while the maximal linear blood flow velocity in the IJV remained unchanged (71 ± 4.9 and 85 ± 8.4 cm/s, P = 0.098). Consistent with previously published studies, the data obtained provide further evidence of active regulation of the venous outflow, probably mediated by certain neurogenic and/or endothelium-dependent mechanisms.
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Affiliation(s)
- Alexey Y Ivanov
- Division of Vascular Surgery, A. L. Polenov Research Institute of Neurosurgery, St. Petersburg, Russian Federation
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19
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Karamat FA, Clark JF, Brewster LM. Is Creatine Kinase the Intrinsic Factor of Smooth Muscle Enhancing Vascular Contractility in Subjects of African Ancestry? Hypertension 2013; 62:e7. [DOI: 10.1161/hypertensionaha.113.01853] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Fares A. Karamat
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Joseph F. Clark
- Department of Neurology, University of Cincinnati, Cincinnati, OH
| | - Lizzy M. Brewster
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
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