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Giza RJ, Farrell MC, Arnold AC, Biaggioni I, Shibao CA. Clinical and neurohormonal characteristics in African Americans with neurogenic orthostatic hypotension. Clin Auton Res 2021; 31:101-107. [PMID: 33502643 DOI: 10.1007/s10286-020-00764-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 12/28/2020] [Indexed: 10/22/2022]
Abstract
PURPOSE Neurogenic orthostatic hypotension (nOH) is the hallmark of neurodegenerative forms of autonomic failure, including pure autonomic failure, multiple system atrophy, and Parkinson's disease. Studies have shown autonomic physiological differences in Africans Americans (AA) such as lower heart rate variability, enhanced blood pressure reactivity, and blunted sympathetic neural response compared to non-Hispanic whites. However, the clinical characteristics and neurohormonal profile of autonomic failure in AA is unknown. METHODS A total of 65 patients with nOH participated in this study (9 AA and 56 non-Hispanic whites). Both groups were of similar age and comorbidity status, and they underwent standardized autonomic testing and assessment of neurohormonal levels and renin activity and aldosterone in supine and upright positions. RESULTS There were no significant differences in baseline autonomic clinical characteristics between non-Hispanic whites and AA with nOH. Non-Hispanic whites demonstrated a significant increase in upright renin activity compared to AA (295 ± 88% vs. 13 ± 13%, respectively). AA showed a blunted increase in aldosterone compared to non-Hispanic whites (188 ± 27% vs. 59 ± 38%, respectively). These results indicated persistent suppression of the renin-angiotensin system in AA, particularly during upright posture. CONCLUSION Our findings demonstrate that AA with nOH have similar clinical characteristics and hemodynamic autonomic profiles, but lower upright renin activity and aldosterone levels, compared to non-Hispanic whites. Renin suppression persists in AA with severe autonomic failure and can potentially contribute to postural changes and supine hypertension.
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Affiliation(s)
- Richard J Giza
- Drexel University College of Medicine, Philadelphia, PA, USA
| | | | - Amy C Arnold
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA, USA.,Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University Medical Center, 506 Robinson Research Building, Nashville, TN, 37232-6602, USA
| | - Italo Biaggioni
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Autonomic Dysfunction Center, Vanderbilt University Medical Center, 506 Robinson Research Building, Nashville, TN, 37232-6602, 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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Tan JW, Gupta T, Manosroi W, Yao TM, Hopkins PN, Williams JS, Adler GK, Romero JR, Williams GH. Dysregulated aldosterone secretion in persons of African descent with endothelin-1 gene variants. JCI Insight 2017; 2:95992. [PMID: 29212952 DOI: 10.1172/jci.insight.95992] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 11/02/2017] [Indexed: 01/05/2023] Open
Abstract
Compared with persons of European descent (ED), persons of African descent (AD) have lower aldosterone (ALDO) levels, with the assumption being that the increased cardiovascular disease (CVD) risk associated with AD is not related to ALDO. However, the appropriateness of the ALDO levels for the volume status in AD is unclear. We hypothesized that, even though ALDO levels are lower in AD, they are inappropriately increased, and therefore, ALDO could mediate the increased CVD in AD. To test this hypothesis, we analyzed data from HyperPATH - 1,788 individuals from the total cohort and 765 restricted to ED-to-AD in a 2:1 match and genotyped for the endothelin-1 gene (EDN1). Linear regression analyses with adjustments were performed. In the total and restricted cohorts, PRA, ALDO, and urinary potassium levels were significantly lower in AD. However, in the AD group, greater ALDO dysregulation was present as evidenced by higher ALDO/plasma renin activity (PRA) ratios (ARR) and sodium-modulated ALDO suppression-to-stimulation indices. Furthermore, EDN1 minor allele carriers had significantly greater ARRs than noncarriers but only in the AD group. ARR levels were modulated by a significant interaction between EDN1 and AD. Thus, EDN1 variants may identify particularly susceptible ADs who will be responsive to treatment targeting ALDO-dependent pathways (e.g., mineralocorticoid-receptor antagonists).
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Affiliation(s)
- Jia W Tan
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Cell & Molecular Biology Laboratory, Department of Cellular Biology & Pharmacology, Faculty of Medicine & Health Sciences, UCSI University, Cheras, Kuala Lumpur, Malaysia
| | - Tina Gupta
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Worapaka Manosroi
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Division of Endocrinology, Bangkok Hospital Chiang Mai, Chiang Mai, Thailand
| | - Tham M Yao
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Paul N Hopkins
- Cardiovascular Genetics Unit, Cardiology Division, Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Jonathan S Williams
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Gail K Adler
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Jose R Romero
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Gordon H Williams
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Hughes AD. How do thiazide and thiazide-like diuretics lower blood pressure? J Renin Angiotensin Aldosterone Syst 2016; 5:155-60. [PMID: 15803433 DOI: 10.3317/jraas.2004.034] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Thiazide diuretics are widely used for the treatment of hypertension, but the mechanism by which these drugs lower blood pressure in the long term remains unknown. This article reviews current knowledge about the hypotensive actions of thiazides and thiazide-like diuretics and discusses possible mechanisms of action.
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Affiliation(s)
- Alun D Hughes
- Clinical Pharmacology, Faculty of Medicine, Imperial College London, London W21NY, UK.
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Tu W, Eckert GJ, Hannon TS, Liu H, Pratt LM, Wagner MA, Dimeglio LA, Jung J, Pratt JH. Racial differences in sensitivity of blood pressure to aldosterone. Hypertension 2014; 63:1212-8. [PMID: 24711519 DOI: 10.1161/hypertensionaha.113.02989] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Blacks in comparison with whites are at risk for a more serious form of hypertension with high rates of complications. Greater sodium retention is thought to underlie the blood pressure (BP)-determining physiology of blacks, but specific mechanisms have not been identified. In a prospective observational study of BP, 226 black children and 314 white children (mean age, 10.6 years) were enrolled initially. Assessments were repeated in 85 blacks and 136 whites after reaching adulthood (mean age, 31 years). The relationship of BP to plasma aldosterone concentration in the context of the prevailing level of plasma renin activity was studied in blacks and whites. In a secondary interventional study, 9-α fludrocortisone was administered for 2 weeks to healthy adult blacks and whites to simulate hyperaldosteronism. BP responses in the 2 race groups were then compared. Although black children had lower levels of plasma renin activity and plasma aldosterone, their BP was positively associated with the plasma aldosterone concentration, an effect that increased as plasma renin activity decreased (P=0.004). Data from black adults yielded similar results. No similar relationship was observed in whites. In the interventional study, 9-α fludrocortisone increased BP in blacks but not in whites. In conclusion, aldosterone sensitivity is a significant determinant of BP in young blacks. Although its role in establishing the risk of hypertension is not known, it could be as relevant as the actual level of aldosterone.
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Affiliation(s)
- Wanzhu Tu
- 541 Clinical Dr, CL 365a, Indianapolis, IN 46202-5111.
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Brewster LM, Seedat YK. Why do hypertensive patients of African ancestry respond better to calcium blockers and diuretics than to ACE inhibitors and β-adrenergic blockers? A systematic review. BMC Med 2013; 11:141. [PMID: 23721258 PMCID: PMC3681568 DOI: 10.1186/1741-7015-11-141] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Accepted: 04/17/2013] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Clinicians are encouraged to take an individualized approach when treating hypertension in patients of African ancestry, but little is known about why the individual patient may respond well to calcium blockers and diuretics, but generally has an attenuated response to drugs inhibiting the renin-angiotensin system and to β-adrenergic blockers. Therefore, we systematically reviewed the factors associated with the differential drug response of patients of African ancestry to antihypertensive drug therapy. METHODS Using the methodology of the systematic reviews narrative synthesis approach, we sought for published or unpublished studies that could explain the differential clinical efficacy of antihypertensive drugs in patients of African ancestry. PUBMED, EMBASE, LILACS, African Index Medicus and the Food and Drug Administration and European Medicines Agency databases were searched without language restriction from their inception through June 2012. RESULTS We retrieved 3,763 papers, and included 72 reports that mainly considered the 4 major classes of antihypertensive drugs, calcium blockers, diuretics, drugs that interfere with the renin-angiotensin system and β-adrenergic blockers. Pharmacokinetics, plasma renin and genetic polymorphisms did not well predict the response of patients of African ancestry to antihypertensive drugs. An emerging view that low nitric oxide and high creatine kinase may explain individual responses to antihypertensive drugs unites previous observations, but currently clinical data are very limited. CONCLUSION Available data are inconclusive regarding why patients of African ancestry display the typical response to antihypertensive drugs. In lieu of biochemical or pharmacogenomic parameters, self-defined African ancestry seems the best available predictor of individual responses to antihypertensive drugs.
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Affiliation(s)
- Lizzy M Brewster
- Departments of Internal and Vascular Medicine, F4-222, Academic Medical Center, Meibergdreef 9, Amsterdam, AZ, 1105, The Netherlands.
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Bernstein AM, Willett WC. Trends in 24-h urinary sodium excretion in the United States, 1957-2003: a systematic review. Am J Clin Nutr 2010; 92:1172-80. [PMID: 20826631 PMCID: PMC2954449 DOI: 10.3945/ajcn.2010.29367] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 07/21/2010] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Few studies have examined temporal trends in sodium intake in the US population. Collections of 24-h urine sodium excretions are reliable markers for dietary sodium intake. OBJECTIVE We examined temporal trends in 24-h urine sodium excretions to estimate temporal trends in sodium intake in the US population. DESIGN We performed a systematic search of English-language articles in MEDLINE for studies that reported collections of 24-h urine sodium excretions in the United States. We estimated mean urine sodium excretions over time for all studies and demographic subgroups. RESULTS We analyzed 38 studies, which dated from 1957 to 2003, and estimated a mean (± SE) 24-h urine sodium excretion per person of 3526 ± 75 mg Na. In a multivariate random-effects model with study year, sex, age, and race, the study year was not associated with any significant change in sodium excretions (coefficient = 154 mg Na · 24 h⁻¹ · 10 y⁻¹; 95% CI: -140, 448 mg Na · 24 h⁻¹ · 10 y⁻¹). In subgroup analyses, there was no significant temporal trend seen in male, female, black, or white study participants. CONCLUSION Sodium intake in the US adult population appears to be well above current guidelines and does not appear to have decreased with time.
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Affiliation(s)
- Adam M Bernstein
- Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.
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Aviv A, Hollenberg NK, Weder AB. Sodium glomerulopathy: tubuloglomerular feedback and renal injury in African Americans. Kidney Int 2004; 65:361-8. [PMID: 14717906 DOI: 10.1111/j.1523-1755.2004.00389.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
African Americans are prone to develop not only essential hypertension but also progressive renal injury. We present a simple model to explain salt-induced renal injury (sodium glomerulopathy) in African Americans, the central features of which are the tubuloglomerular feedback and the balance/imbalance between the vascular tones of the afferent and efferent glomerular arterioles. We propose that in African Americans, habitual consumption of high salt causes chronic intermittent tubular hyperperfusion of the macula densa, resulting in a rightward and upward resetting of the operating point for the tubuloglomerular feedback. The resetting of the operating point causes an imbalance between the vascular tones of the afferent/efferent arterioles, a rise in the glomerular capillary hydraulic pressure, and consequent hyperfiltration. Increased susceptibility to glomerular hyperfiltration of African Americans on a high salt intake may explain their proclivity to progressive renal injury associated with essential hypertension.
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Affiliation(s)
- Abraham Aviv
- Hypertension Research Center, Cardiovascular Research Institute, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA.
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Abstract
Based on racial differences in urinary potassium excretion and responses to diuretics, we present a model suggesting that a major cause of sodium sensitivity in blacks is an augmented activity of the Na-K-2Cl cotransport in the thick ascending limb of Henle's loop. This would result in an increased ability to conserve not only sodium but also water, and an upward and rightward shift in the operating point of tubuloglomerular feedback, which may cause an increase in the glomerular capillary hydraulic pressure and predilection to glomerular injury with and without hypertension. In this sense, the biological implication of sodium sensitivity in blacks and in humans in general has ramifications above and beyond salt-evoked increase in blood pressure.
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Affiliation(s)
- Abraham Aviv
- Hypertension Research Center, Cardiovascular Research Institute, University of Medicine & Dentistry of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA.
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Abdel-Rahman SM, Kauffman RE. THEINTEGRATION OFPHARMACOKINETICS ANDPHARMACODYNAMICS: Understanding Dose-Response. Annu Rev Pharmacol Toxicol 2004; 44:111-36. [PMID: 14744241 DOI: 10.1146/annurev.pharmtox.44.101802.121347] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pharmacokinetic (PK) and pharmacodynamic (PD) studies have proven to be powerful and instructive tools, particularly in elucidating important aspects of human pharmacology. Nevertheless, they remain imperfect tools in that they only allow researchers to indirectly extrapolate, through computational modeling, the dynamic processes of drug action. Furthermore, neither tool alone provides a complete nor necessarily relevant picture of drug action. This review explores the utility and applications of PK and PD in the study of drugs, provides examples of lessons learned from their application to studies of human pharmacology, points out some of their limitations, and advances the thesis that these tools ideally should be employed together in an integrated approach. As we continue to apply these tools across the continuum of age and disease, they provide a powerful means to enhance our understanding of drug action, drug interactions, and intrinsic host factors that influence pharmacologic response.
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Affiliation(s)
- Susan M Abdel-Rahman
- Division of Pediatric Clinical Pharmacology and Medical Toxicology, The Children's Mercy Hospital and Clinics, Department of Pediatrics, University of Missouri-Kansas City, Kansas City, Missouri 64108, USA.
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