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Nazari S, Moosavi SMS. Temporal patterns of alterations in obesity index, lipid profile, renal function and blood pressure during the development of hypertension in male, but not female, rats fed a moderately high-fat diet. Arch Physiol Biochem 2022; 128:897-909. [PMID: 32195603 DOI: 10.1080/13813455.2020.1739713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT Male Sprague-Dawley rats consuming a moderately high-fat (MHF)-diet diverge into obesity-prone (OP) with hypertension and obesity-resistant. OBJECTIVES To study the temporal inter-relationships between body-weight, obesity-index, plasma lipid-profile, renal functional parameters and systolic-pressure alterations during 10-weeks feeding MHF or normal diet to male and female rats. METHODS Body-weight, obesity-index and systolic-pressure were measured weekly, while metabolic-cage and blood-sampling protocols were performed every other week. After 10-weeks, renal excretory responses to acute salt-loading and renal autoregulation were examined. RESULTS The male-OP group had progressively increased body-weight, plasma-triglyceride and systolic-pressure from Weeks 2, 4 and 5, respectively, lower renal sodium-excretion at weeks 4-8 and finally, delayed excretory response to salt-loading and rightward and downward shifts in renal autoregulatory curves compared to all other groups. CONCLUSION Feeding the MHF-diet in male-OP rats led to a greater weight-gain and adiposity followed by the development of atherogenic-hyperlipidaemia and persistently impaired pressure-natriuresis to induce hypertension.
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Affiliation(s)
- Somayeh Nazari
- Department of Physiology, The Medical School, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seyed Mostafa Shid Moosavi
- Department of Physiology, The Medical School, Shiraz University of Medical Sciences, Shiraz, Iran
- Shiraz Nephro-Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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2
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Jensen LJ, Lund MA, Salomonsson M, Goetze JP, Jonassen TE, Holstein-Rathlou NH, Axelsen LN, Sørensen CM. Diet-induced hypertension in rats is associated with increased renal vasoconstrictor response to angiotensin II after imitated endothelial dysfunction. Microvasc Res 2022; 141:104333. [DOI: 10.1016/j.mvr.2022.104333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/21/2021] [Accepted: 01/24/2022] [Indexed: 11/16/2022]
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3
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Nazari S, Haghani M, Moosavi SMS. Bilateral renal denervation prevents the development of hypertension during diet-induced obesity in male rats. Exp Physiol 2021; 106:2248-2261. [PMID: 34476853 DOI: 10.1113/ep089545] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 08/31/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the role of the renal nerves in the development of obesity, hyperlipidaemia and hypertension during the long-term feeding of a moderately high-fat diet in male obesity-prone rats? What is the main finding and its importance? The renal nerves play a prominent mediatory role, without influencing the establishment of visceral adiposity and atherogenic hyperlipidaemia, in the induction and progression of pressure natriuresis impairment and hypertension during the developmental period of diet-induced obesity. ABSTRACT Feeding a moderately high-fat (MHF) diet in male Sprague-Dawley rats induces obesity, pressure natriuresis impairment and hypertension. This study investigated the role of the renal nerves in the impaired pressure natriuresis and hypertension caused by feeding a MHF diet. After collecting baseline data on day 0, 12 rats remained on a low-fat diet (LF group) while the others were switched onto a MHF diet and diverged into obesity-resistant (OR) or obesity-prone (OP). After 4 weeks, half of the OR and OP rats underwent bilateral renal denervation (BRD) to generate four groups: OR, OR/BRD, OP and OP/BRD (n = 12). During 10 weeks, body weight, obesity index, systolic pressure and renal excretory function were measured regularly. After 10 weeks, renal excretory responses to acute salt loading and renal autoregulation were evaluated. The OP and OP/BRD groups had greater increases of body weight and obesity index during the dietary period compared to the other groups, and by week 10 their body weight (425.1 ± 7.2 and 411.9 ± 5.1 g) became considerably larger than that of the LF group (358.5 ± 6.2 g). Renal sodium excretion was reduced by ∼20% at week 4 in the OP and OP/BRD groups, while only the OP group had lower sodium excretion at weeks 6-8 and higher systolic pressure over weeks 5-10 than the other groups and its week 10 systolic pressure reached 138.1 ± 6.7 versus 123.6 ± 2.7 mmHg of the LF group. The OP group showed delayed renal excretory responses to salt loading with rightward and downward shifts in renal autoregulatory curves. Therefore, the renal nerves exert a main mediatory role in the development of pressure natriuresis impairment and hypertension as obesity is established due to the long-term consumption of the MHF diet in male OP rats.
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Affiliation(s)
- Somayeh Nazari
- Department of Physiology, The Medical School, Shiraz University of Medical Sciences, Shiraz, Iran.,Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Masoud Haghani
- Department of Physiology, The Medical School, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seyed Mostafa Shid Moosavi
- Department of Physiology, The Medical School, Shiraz University of Medical Sciences, Shiraz, Iran.,Shiraz Nephro-Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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4
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High-Fat Diets Modify the Proteolytic Activities of Dipeptidyl-Peptidase IV and the Regulatory Enzymes of the Renin-Angiotensin System in Cardiovascular Tissues of Adult Wistar Rats. Biomedicines 2021; 9:biomedicines9091149. [PMID: 34572336 PMCID: PMC8470673 DOI: 10.3390/biomedicines9091149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 08/17/2021] [Accepted: 09/01/2021] [Indexed: 01/02/2023] Open
Abstract
(1) Background: The replacement of diets high in saturated fat (SAFA) with monounsaturated fatty acids (MUFA) is associated with better cardiovascular function and is related to the modulation of the activity of the local renin–angiotensin system (RAS) and the collagenase activity of dipeptidyl peptidase IV (DPP-IV). The objective of the work was to verify the capacity of different types of dietary fat on the regulatory activities of RAS and DPP-IV. (2) Methods: Male Wistar rats were fed for 24 weeks with three different diets: the standard diet (S), the standard diet supplemented with virgin olive oil (20%) (VOO), or with butter (20%) plus cholesterol (0.1%) (Bch). The proteolytic activities were determined by fluorometric methods in the soluble (sol) and membrane-bound (mb) fractions of the left ventricle and atrium, aorta, and plasma samples. (3) Results: With the VOO diet, angiotensinase values were significantly lower than with the Bch diet in the aorta (GluAP and ArgAP (mb)), ventricle (ArgAP (mb)) and atrium (CysAP (sol)). Significant decreases in DPP-IV (mb) activity occurred with the Bch diet in the atrium and aorta. The VOO diet significantly reduced the activity of the cardiac damage marker LeuAP (mb) in the ventricle and aorta, except for LeuAP (sol) in the ventricle, which was reduced with the Bch diet. (4) Conclusions: The introduction into the diet of a source rich in MUFA would have a beneficial cardiovascular effect on RAS homeostasis and cardiovascular functional stability.
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5
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Huang C, AlMarabeh S, Cavers J, Abdulla MH, Johns EJ. Effects of intracerebroventricular leptin and orexin-A on the baroreflex control of renal sympathetic nerve activity in conscious rats fed a normal or high-fat diet. Clin Exp Pharmacol Physiol 2021; 48:585-596. [PMID: 33352624 DOI: 10.1111/1440-1681.13451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 08/21/2020] [Accepted: 12/01/2020] [Indexed: 11/30/2022]
Abstract
This study examined the effect of leptin and orexin-A on autonomic baroreflex control in conscious Wistar rats exposed to high-fat (45% fat) or normal (3.4%) diet for 4 weeks. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP) and heart rate (HR) were monitored during the generation of baroreflex gain curves and acute volume expansion (VEP). Intracerebroventricular (ICV) leptin (1 μg/min) increased RSNA in the normal diet group (0.31 ± 0.04 vs 0.23 ± 0.03 mV/s) and MAP in the high-fat diet group (115 ± 5 vs 105 ± 5 mm Hg, P < .05). Orexin-A (50 ng/min) increased RSNA, HR and MAP in the high-fat diet group (0.26 ± 0.03 vs 0.22 ± 0.02 mV/s, 454 ± 8 vs 417 ± 12 beats/min, 117 ± 1 vs 108 ± 1 mm Hg) and the normal diet group (0.18 ± 0.05 vs 0.17 ± 0.05 mV/s, 465 ± 10 vs 426 ± 6 beats/min, 116 ± 2 vs 104 ± 3 mm Hg). Baroreflex sensitivity for RSNA was increased during ICV leptin by 50% in the normal diet group, compared to 14% in the high-fat diet group (P < .05). Similarly, orexin-A increased baroreflex sensitivity by 56% and 50% in the high-fat and normal diet groups, respectively (all P < .05). During ICV saline, VEP decreased RSNA by 31 ± 5% (P < .05) after 10 minutes and the magnitude of this response was blunted during ICV infusion of leptin (17 ± 2%, P < .05) but not orexin-A in the normal diet group. RSNA response to VEP was not changed during ICV leptin or orexin-A in the high-fat diet group. These findings indicate possible central roles for leptin and orexin-A in modulating the baroreflexes under normal or increased fat intake in conscious rats and potential therapeutic approaches for obesity associated hypertension.
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Affiliation(s)
- Chunlong Huang
- Department of Physiology, Western Gateway Building, University College Cork, Cork, Ireland
| | - Sara AlMarabeh
- Department of Physiology, Western Gateway Building, University College Cork, Cork, Ireland
| | - Jeremy Cavers
- Department of Physiology, Western Gateway Building, University College Cork, Cork, Ireland
| | - Mohammed H Abdulla
- Department of Physiology, Western Gateway Building, University College Cork, Cork, Ireland
| | - Edward J Johns
- Department of Physiology, Western Gateway Building, University College Cork, Cork, Ireland
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6
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AlMarabeh S, O'Neill J, Cavers J, Lucking EF, O'Halloran KD, Abdulla MH. Chronic intermittent hypoxia impairs diuretic and natriuretic responses to volume expansion in rats with preserved low-pressure baroreflex control of the kidney. Am J Physiol Renal Physiol 2021; 320:F1-F16. [PMID: 33166181 DOI: 10.1152/ajprenal.00377.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/26/2020] [Accepted: 11/03/2020] [Indexed: 12/17/2022] Open
Abstract
We examined the effects of exposure to chronic intermittent hypoxia (CIH) on baroreflex control of renal sympathetic nerve activity (RSNA) and renal excretory responses to volume expansion (VE) before and after intrarenal transient receptor potential vanilloid 1 (TRPV1) blockade by capsaizepine (CPZ). Male Wistar rats were exposed to 96 cycles of hypoxia per day for 14 days (CIH) or normoxia. Urine flow and absolute Na+ excretion during VE were less in CIH-exposed rats, but the progressive decrease in RSNA during VE was preserved. Assessment of the high-pressure baroreflex revealed an increase in the operating and response range of RSNA and decreased slope in CIH-exposed rats with substantial hypertension [+19 mmHg basal mean arterial pressure (MAP)] but not in a second cohort with modest hypertension (+12 mmHg). Intrarenal CPZ caused diuresis, natriuresis, and a reduction in MAP in sham-exposed (sham) and CIH-exposed rats. After intrarenal CPZ, diuretic and natriuretic responses to VE in CIH-exposed rats were equivalent to those of sham rats. TRPV1 expression in the renal pelvic wall was similar in both experimental groups. Exposure to CIH did not elicit glomerular hypertrophy, renal inflammation, or oxidative stress. We conclude that exposure to CIH 1) does not impair the low-pressure baroreflex control of RSNA; 2) has modest effects on the high-pressure baroreflex control of RSNA, most likely indirectly due to hypertension; 3) can elicit hypertension in the absence of kidney injury; and 4) impairs diuretic and natriuretic responses to fluid overload. Our results suggest that exposure to CIH causes renal dysfunction, which may be relevant to obstructive sleep apnea.
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Affiliation(s)
- Sara AlMarabeh
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Julie O'Neill
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Jeremy Cavers
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Eric F Lucking
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Mohammed H Abdulla
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
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7
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Valenzuela PL, Carrera-Bastos P, Gálvez BG, Ruiz-Hurtado G, Ordovas JM, Ruilope LM, Lucia A. Lifestyle interventions for the prevention and treatment of hypertension. Nat Rev Cardiol 2020; 18:251-275. [PMID: 33037326 DOI: 10.1038/s41569-020-00437-9] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/24/2020] [Indexed: 02/07/2023]
Abstract
Hypertension affects approximately one third of the world's adult population and is a major cause of premature death despite considerable advances in pharmacological treatments. Growing evidence supports the use of lifestyle interventions for the prevention and adjuvant treatment of hypertension. In this Review, we provide a summary of the epidemiological research supporting the preventive and antihypertensive effects of major lifestyle interventions (regular physical exercise, body weight management and healthy dietary patterns), as well as other less traditional recommendations such as stress management and the promotion of adequate sleep patterns coupled with circadian entrainment. We also discuss the physiological mechanisms underlying the beneficial effects of these lifestyle interventions on hypertension, which include not only the prevention of traditional risk factors (such as obesity and insulin resistance) and improvements in vascular health through an improved redox and inflammatory status, but also reduced sympathetic overactivation and non-traditional mechanisms such as increased secretion of myokines.
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Affiliation(s)
| | - Pedro Carrera-Bastos
- Centre for Primary Health Care Research, Lund University/Region Skane, Skane University Hospital, Malmö, Sweden
| | - Beatriz G Gálvez
- Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain
| | - Gema Ruiz-Hurtado
- Research Institute of the Hospital Universitario 12 de Octubre (imas12), Madrid, Spain.,CIBER-CV, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - José M Ordovas
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA.,IMDEA Alimentacion, Madrid, Spain
| | - Luis M Ruilope
- Research Institute of the Hospital Universitario 12 de Octubre (imas12), Madrid, Spain.,CIBER-CV, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Alejandro Lucia
- Faculty of Sport Sciences, Universidad Europea de Madrid, Madrid, Spain. .,Research Institute of the Hospital Universitario 12 de Octubre (imas12), Madrid, Spain.
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8
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9
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Sucedaram Y, Johns EJ, Husain R, Sattar MA, Abdulla M, Khalilpourfarshbafi M, Abdullah NA. Comparison of high-fat style diet-induced dysregulation of baroreflex control of renal sympathetic nerve activity in intact and ovariectomized female rats: Renal sympathetic nerve activity in high-fat style diet fed intact and ovariectomized female rats. Exp Biol Med (Maywood) 2020; 245:761-776. [PMID: 32212858 DOI: 10.1177/1535370220915673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
IMPACT STATEMENT Over activation of renal sensory nerve in obesity blunts the normal regulation of renal sympathetic nerve activity. To date, there is no investigation that has been carried out on baroreflex regulation of renal sympathetic nerve activity in obese ovarian hormones deprived rat model, and the effect of renal denervation on the baroreflex regulation of renal sympathetic nerve activity. Thus, we investigated the role of renal innervation on baroreflex regulation of renal sympathetic nerve activity in obese intact and ovariectomized female rats. Our data demonstrated that in obese states, the impaired baroreflex control is indistinguishable between ovarian hormones deprived and non-deprived states. This study will be of substantial interest to researchers working on the impact of diet-induced hypertension in pre- and postmenopausal women. This study provides insight into health risks amongst obese women regardless of their ovarian hormonal status and may be integrated in preventive health strategies.
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Affiliation(s)
- Yamuna Sucedaram
- Department of Pharmacology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Edward James Johns
- Department of Physiology, University College Cork, Cork T12 K8AF, Ireland
| | - Ruby Husain
- Department of Physiology, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Munavvar Abdul Sattar
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, USM Pulau Pinang 11800, Malaysia.,Faculty of Pharmacy, MAHSA University, Jenjarom 42610, Malaysia
| | - Mohammed Abdulla
- Department of Physiology, University College Cork, Cork T12 K8AF, Ireland
| | | | - Nor Azizan Abdullah
- Department of Pharmacology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
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10
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Hall JE, do Carmo JM, da Silva AA, Wang Z, Hall ME. Obesity, kidney dysfunction and hypertension: mechanistic links. Nat Rev Nephrol 2020; 15:367-385. [PMID: 31015582 DOI: 10.1038/s41581-019-0145-4] [Citation(s) in RCA: 304] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Excessive adiposity raises blood pressure and accounts for 65-75% of primary hypertension, which is a major driver of cardiovascular and kidney diseases. In obesity, abnormal kidney function and associated increases in tubular sodium reabsorption initiate hypertension, which is often mild before the development of target organ injury. Factors that contribute to increased sodium reabsorption in obesity include kidney compression by visceral, perirenal and renal sinus fat; increased renal sympathetic nerve activity (RSNA); increased levels of anti-natriuretic hormones, such as angiotensin II and aldosterone; and adipokines, particularly leptin. The renal and neurohormonal pathways of obesity and hypertension are intertwined. For example, leptin increases RSNA by stimulating the central nervous system proopiomelanocortin-melanocortin 4 receptor pathway, and kidney compression and RSNA contribute to renin-angiotensin-aldosterone system activation. Glucocorticoids and/or oxidative stress may also contribute to mineralocorticoid receptor activation in obesity. Prolonged obesity and progressive renal injury often lead to the development of treatment-resistant hypertension. Patient management therefore often requires multiple antihypertensive drugs and concurrent treatment of dyslipidaemia, insulin resistance, diabetes and inflammation. If more effective strategies for the prevention and control of obesity are not developed, cardiorenal, metabolic and other obesity-associated diseases could overwhelm health-care systems in the future.
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Affiliation(s)
- John E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA. .,Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, MS, USA.
| | - Jussara M do Carmo
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.,Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, MS, USA
| | - Alexandre A da Silva
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.,Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, MS, USA
| | - Zhen Wang
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.,Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, MS, USA
| | - Michael E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.,Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
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11
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Syme C, Shin J, Richer L, Gaudet D, Paus T, Pausova Z. Sex Differences in Blood Pressure Hemodynamics in Middle-Aged Adults With Overweight and Obesity. Hypertension 2019; 74:407-412. [DOI: 10.1161/hypertensionaha.119.13058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
High blood pressure (BP) is the strongest modifiable risk factor for cardiovascular disease. Overweight/obesity is a major risk factor of high BP. Multiple sex differences exist in mechanistic pathways that increase BP in overweight/obesity. They may result in a sex-specific pattern of BP hemodynamics—males and females may vary in the relative contributions of stroke volume, total peripheral resistance (TPR), and heart rate to higher BP. We investigated this possibility in a population-based sample of middle-aged adults (36–65 years). The total sample (n=618) included 289 males and 329 females; 79% of males and 66% of females were overweight. In all, we measured BP, stroke volume, TPR, and heart rate beat-by-beat during a 52-minute protocol that included changes in posture and mental stress. We assessed the relative contributions of stroke volume, TPR, and heart rate to BP at each minute of the protocol. We observed marked sex differences in BP hemodynamics in overweight/obese individuals: the main determinant of higher BP was TPR in males (49% versus only 35% in females,
P
=0.008), whereas it was stroke volume in females (51% versus only 35% in males,
P
=0.006). These sex differences were most apparent when standing or sitting at rest. No such differences were seen in normal-weight individuals in whom the main determinant of higher BP was TPR in both sexes. Our study suggests that, in middle-aged adults, marked sex differences exist in BP hemodynamics, contributing to high BP in overweight/obese but not normal-weight individuals. As such, this study may contribute to precision medicine in hypertension.
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Affiliation(s)
- Catriona Syme
- From the Hospital for Sick Children (C.S., J.S., Z.P.), University of Toronto, Canada
- Departments of Physiology and Nutritional Sciences (C.S., J.S., Z.P.), University of Toronto, Canada
| | - Jean Shin
- From the Hospital for Sick Children (C.S., J.S., Z.P.), University of Toronto, Canada
- Departments of Physiology and Nutritional Sciences (C.S., J.S., Z.P.), University of Toronto, Canada
| | - Louis Richer
- Department of Health Sciences Université du Québec à Chicoutimi, Canada (L.R.)
| | - Daniel Gaudet
- Community Genomic Centre, Université de Montréal, Chicoutimi, Canada (D.G.)
| | - Tomáš Paus
- Departments of Psychology and Psychiatry (T.P.), University of Toronto, Canada
- Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, Toronto, Canada (T.P.)
| | - Zdenka Pausova
- From the Hospital for Sick Children (C.S., J.S., Z.P.), University of Toronto, Canada
- Departments of Physiology and Nutritional Sciences (C.S., J.S., Z.P.), University of Toronto, Canada
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12
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Cardiovascular and hidroelectrolytic changes in rats fed with high-fat diet. Behav Brain Res 2019; 373:112075. [PMID: 31284013 DOI: 10.1016/j.bbr.2019.112075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/14/2019] [Accepted: 07/05/2019] [Indexed: 01/18/2023]
Abstract
Obesity activates the renin-angiotensin and sympathetic systems facilitating hypertension and changes in the hydroelectrolytic balance. In the present study, in rats fed with high-fat diet (HFD), we investigated daily water intake and urinary excretion, prandial consumption of water and the changes in blood pressure and water intake to intracerebroventricular (icv) angiotensin II (ANG II). Male Holtzman rats (290-320 g) were fed with standard diet (SD, 11% calories from fat) or HFD (45% calories from fat) for 6 weeks. Part of the animals received a stainless steel cannula in the lateral ventricle (LV) at the 6th week after the beginning of the diets and the experiments were performed at the 7th week. The pressor effect, but not the dipsogenic response to acute icv injection of ANG II, was potentiated in the HFD rats. Daily water intake and urinary volume were reduced in rats fed with HFD with no significant changes in sodium excretion. Prandial water consumption was also reduced in rats ingesting HFD, an effect almost totally reverted blocking salivation with atropine. These results show a potentiation of the pressor response to icv ANG II in HFD-fed rats, without changing icv ANG II-induced water intake. In addition, prandial and daily water intake and urinary volume were reduced in HFD-fed rats, without changing sodium excretion. Salivation in rats ingesting HFD may play a role in the reduced prandial and daily water intake.
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13
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AlMarabeh S, Abdulla MH, O'Halloran KD. Is Aberrant Reno-Renal Reflex Control of Blood Pressure a Contributor to Chronic Intermittent Hypoxia-Induced Hypertension? Front Physiol 2019; 10:465. [PMID: 31105584 PMCID: PMC6491928 DOI: 10.3389/fphys.2019.00465] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 04/04/2019] [Indexed: 12/16/2022] Open
Abstract
Renal sensory nerves are important in the regulation of body fluid and electrolyte homeostasis, and blood pressure. Activation of renal mechanoreceptor afferents triggers a negative feedback reno-renal reflex that leads to the inhibition of sympathetic nervous outflow. Conversely, activation of renal chemoreceptor afferents elicits reflex sympathoexcitation. Dysregulation of reno-renal reflexes by suppression of the inhibitory reflex and/or activation of the excitatory reflex impairs blood pressure control, predisposing to hypertension. Obstructive sleep apnoea syndrome (OSAS) is causally related to hypertension. Renal denervation in patients with OSAS or in experimental models of chronic intermittent hypoxia (CIH), a cardinal feature of OSAS due to recurrent apnoeas (pauses in breathing), results in a decrease in circulating norepinephrine levels and attenuation of hypertension. The mechanism of the beneficial effect of renal denervation on blood pressure control in models of CIH and OSAS is not fully understood, since renal denervation interrupts renal afferent signaling to the brain and sympathetic efferent signals to the kidneys. Herein, we consider the currently proposed mechanisms involved in the development of hypertension in CIH disease models with a focus on oxidative and inflammatory mediators in the kidneys and their potential influence on renal afferent control of blood pressure, with wider consideration of the evidence available from a variety of hypertension models. We draw focus to the potential contribution of aberrant renal afferent signaling in the development, maintenance and progression of high blood pressure, which may have relevance to CIH-induced hypertension.
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Affiliation(s)
- Sara AlMarabeh
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Mohammed H Abdulla
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
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14
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Spradley FT. Sympathetic nervous system control of vascular function and blood pressure during pregnancy and preeclampsia. J Hypertens 2019; 37:476-487. [PMID: 30160658 PMCID: PMC6355368 DOI: 10.1097/hjh.0000000000001901] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
: Proper vascular tone and blood pressure regulation during pregnancy are important for immediate and long-term cardiovascular health of the mother and her offspring. Preeclampsia is clinically defined as new-onset maternal hypertension accompanied by cardiovascular, renal, and/or neural abnormalities presenting in the second half of pregnancy. There is strong evidence to support that preeclampsia is mediated by attenuations in uteroplacental vascular remodeling and increases in vasoconstriction with subsequent placental ischemia/reperfusion-induced release of hypertensive substances into the maternal circulation. These include antiangiogenic and pro-inflammatory factors. There is also evidence implicating increased sympathetic nervous system activity (SNA) in this maternal disorder, but this mostly includes data correlating severity of disease with catecholamine levels and elevated muscle SNA. These measurements have not confirmed a causative role for SNA in the pathogenesis of preeclampsia. Therefore, studies are needed to provide a comprehensive understanding of SNA and its control of vascular function and blood pressure regulation during normal pregnancy in order to set the stage for exploring the mechanisms mediating the exaggerated SNA and signaling during preeclampsia. This review examines the role of SNA in control of uteroplacental vascular tone and blood pressure regulation during normal pregnancy. Furthermore, it is proposed that over-activation of the SNA contributes to altered uteroplacental vascular tone and perfusion leading to placental ischemic events and modulates the systemic vasoconstriction and hypertensive responses to soluble placenta ischemic factors. Recognizing the integrative role and importance of SNA in the pathophysiology of preeclampsia will advance our understanding of this maternal disorder.
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Affiliation(s)
- Frank T Spradley
- Department of Surgery, The University of Mississippi Medical Center, Jackson, Mississippi, USA
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McPherson KC, Shields CA, Poudel B, Fizer B, Pennington A, Szabo-Johnson A, Thompson WL, Cornelius DC, Williams JM. Impact of obesity as an independent risk factor for the development of renal injury: implications from rat models of obesity. Am J Physiol Renal Physiol 2018; 316:F316-F327. [PMID: 30539649 DOI: 10.1152/ajprenal.00162.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diabetes and hypertension are the major causes of chronic kidney disease (CKD). Epidemiological studies within the last few decades have revealed that obesity-associated renal disease is an emerging epidemic and that the increasing prevalence of obesity parallels the increased rate of CKD. This has led to the inclusion of obesity as an independent risk factor for CKD. A major complication when studying the relationship between obesity and renal injury is that cardiovascular and metabolic disorders that may result from obesity including hyperglycemia, hypertension, and dyslipidemia, or the cluster of these disorders [defined as the metabolic syndrome, (MetS)] also contribute to the development and progression of renal disease. The associations between hyperglycemia and hypertension with renal disease have been reported extensively in patients suffering from obesity. Currently, there are several obese rodent models (high-fat diet-induced obesity and leptin signaling dysfunction) that exhibit characteristics of MetS. However, the available obese rodent models currently have not been used to investigate the impact of obesity alone on the development of renal injury before hypertension and/or hyperglycemia. Therefore, the aim of this review is to describe the incidence and severity of renal disease in these rodent models of obesity and determine which models are suitable to study the independent effects obesity on the development and progression of renal disease.
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Affiliation(s)
- Kasi C McPherson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Corbin A Shields
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Bibek Poudel
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Brianca Fizer
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Alyssa Pennington
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Ashley Szabo-Johnson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Willie L Thompson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Denise C Cornelius
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi.,Department of Emergency Medicine, University of Mississippi Medical Center , Jackson, Mississippi
| | - Jan M Williams
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
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Chaudhary P, Schreihofer AM. Improved glucose homeostasis in male obese Zucker rats coincides with enhanced baroreflexes and activation of the nucleus tractus solitarius. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1195-R1209. [PMID: 30256679 DOI: 10.1152/ajpregu.00195.2018] [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: 12/17/2022]
Abstract
Young adult male obese Zucker rats (OZR) develop insulin resistance and hypertension with impaired baroreflex-mediated bradycardia and activation of nucleus tractus solitarius (NTS). Because type 1 diabetic rats also develop impaired baroreflex-mediated NTS activation, we hypothesized that improving glycemic control in OZR would enhance compromised baroreflexes and NTS activation. Fasting blood glucose measured by telemetry was comparable in OZR and lean Zucker rats (LZR) at 12-17 wk. However, with access to food, OZR were chronically hyperglycemic throughout this age range. By 15-17 wk of age, tail samples yielded higher glucose values than those measured by telemetry in OZR but not LZR, consistent with reports of exaggerated stress responses in OZR. Injection of glucose (1g/kg ip) produced larger rises in glucose and areas under the curve in OZR than LZR. Treatment with metformin (300 mg·kg-1·day-1) or pioglitazone (5 mg·kg-1·day-1) in drinking water for 2-3 wk normalized fed glucose levels in OZR with no effect in LZR. After metformin treatment, area under the curve for blood glucose after glucose injection was reduced in OZR and comparable to LZR. Hyperinsulinemia was slightly reduced by each treatment in OZR, but insulin was still greatly elevated compared with LZR. Neither treatment reduced hypertension in OZR, but both treatments significantly improved the blunted phenylephrine-induced bradycardia and NTS c-Fos expression in OZR with no effect in LZR. These data suggest that restoring glycemic control in OZR enhances baroreflex control of heart rate by improving the response of the NTS to raising arterial pressure, even in the presence of hyperinsulinemia and hypertension.
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Affiliation(s)
- Parul Chaudhary
- Department of Physiology and Anatomy, University of North Texas Health Science Center , Fort Worth, Texas
| | - Ann M Schreihofer
- Department of Physiology and Anatomy, University of North Texas Health Science Center , Fort Worth, Texas
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17
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Long-term diet-induced hypertension in rats is associated with reduced expression and function of small artery SKCa, IKCa, and Kir2.1 channels. Clin Sci (Lond) 2018; 132:461-474. [DOI: 10.1042/cs20171408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/24/2018] [Accepted: 02/01/2018] [Indexed: 02/07/2023]
Abstract
Abdominal obesity and/or a high intake of fructose may cause hypertension. K+ channels, Na/K-ATPase, and voltage-gated Ca2+ channels are crucial determinants of resistance artery tone and thus the control of blood pressure. Limited information is available on the role of K+ transporters in long-term diet-induced hypertension in rats. We hypothesized that a 28-week diet rich in fat, fructose, or both, will lead to changes in K+ transporter expression and function, which is associated with increased blood pressure and decreased arterial function. Male Sprague–Dawley (SD) rats received a diet containing normal chow (Control), high-fat chow (High Fat), high-fructose in drinking water (High Fructose), or a combination of high-fat and high-fructose diet (High Fat/Fruc) for 28 weeks from the age of 4 weeks. Measurements included body weight (BW), systolic blood pressure (SBP), mRNA expression of vascular K+ transporters, and vessel myography in small mesenteric arteries (SMAs). BW was increased in the High Fat and High Fat/Fruc groups, and SBP was increased in the High Fat/Fruc group. mRNA expression of small conductance calcium-activated K+ channel (SKCa), intermediate conductance calcium-activated K+ (IKCa), and Kir2.1 inward rectifier K+ channels were reduced in the High Fat/Fruc group. Reduced endothelium-derived hyperpolarization (EDH)-type relaxation to acetylcholine (ACh) was seen in the High Fat and High Fat/Fruc groups. Ba2+-sensitive dilatation to extracellular K+ was impaired in all the experimental diet groups. In conclusion, reduced expression and function of SKCa, IKCa, and Kir2.1 channels are associated with elevated blood pressure in rats fed a long-term High Fat/Fruc. Rats fed a 28-week High Fat/Fruc provide a relevant model of diet-induced hypertension.
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Lund MT, Salomonsson M, Jonassen TEN, Holstein-Rathlou NH. A method for assessment of the dynamic response of the arterial baroreflex. Acta Physiol (Oxf) 2018; 222. [PMID: 28872781 DOI: 10.1111/apha.12962] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 07/11/2017] [Accepted: 08/30/2017] [Indexed: 11/28/2022]
Abstract
AIM The baroreflex is a key mechanism in cardiovascular regulation, and alterations in baroreceptor function are seen in many diseases, including heart failure, obesity and hypertension. We propose a new method for analysing baroreceptor function from continuous blood pressure (BP) and heart rate (HR) in both health and disease. METHODS Forty-eight-hour data series of BP and HR were collected with telemetry. Sprague Dawley rats on standard chow (n = 11) served as controls, while rats on a high-fat, high-fructose (HFHC) diet (n = 6) constituted the obese-hypertensive model. A third group of rats underwent autonomic blockade (n = 6). An autoregressive-moving-average with exogenous inputs (ARMAX) model was applied to the data and compared with the α-coefficient. RESULTS Autonomic blockade caused a significant reduction in the strength of the baroreflex as estimated by ARMAX [ARMAX- baroreflex sensitivity (BRS)] -0.03 ± 0.01 vs. -0.19 ± 0.04 bpm heartbeat-1) . Both methods showed a ~50% reduction in BRS in the obese-hypertensive group compared with control (body weight 531 ± 27 vs. 458 ± 19 g, P < 0.05; mean arterial pressure 119 ± 3 vs. 102 ± 1 mmHg, P < 0.05; ARMAX-BRS -0.08 ± 0.01 vs. -0.15 ± 0.01 bpm heartbeat-1 , P < 0.05; α-coefficient BRS 0.51 ± 0.07 vs. 0.89 ± 0.07 ms mmHg-1 , P < 0.05). The ARMAX method additionally showed the open-loop gain of the baroreflex to be reduced by ~50% in the obese-hypertensive group (-2.3 ± 0.3 vs. -4.1 ± 0.3 bpm, P < 0.05), while the rate constant was similar between groups. CONCLUSION The ARMAX model represents an efficient method for estimating several aspects of the baroreflex. The open-loop gain of the baroreflex was attenuated in obese-hypertensive rats compared with control, while the time response was similar. The algorithm can be applied to other species including humans.
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Affiliation(s)
- M. T. Lund
- Department of Biomedical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - M. Salomonsson
- Department of Biomedical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - T. E. N. Jonassen
- Department of Biomedical Sciences; University of Copenhagen; Copenhagen N Denmark
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19
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Affiliation(s)
- B. L. Jensen
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense C Denmark
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Khan SA, Sattar MZA, Abdullah NA, Rathore HA, Ahmad A, Abdulla MH, Johns EJ. Improvement in baroreflex control of renal sympathetic nerve activity in obese Sprague Dawley rats following immunosuppression. Acta Physiol (Oxf) 2017; 221:250-265. [PMID: 28456134 DOI: 10.1111/apha.12891] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 02/18/2017] [Accepted: 04/26/2017] [Indexed: 12/14/2022]
Abstract
AIM This investigation explored the hypothesis that in obesity an inflammatory response in the kidney contributed to a renal nerve-dependent blunting of the baroreflex regulation of renal sympathetic nerve activity. METHODS Rats received a normal (12% kcal) or high-fat (45% kcal) diet for 8 weeks plus daily injections of vehicle (0.9% NaCl i.p) or tacrolimus (0.25 mg kg-1 day-1 i.p) from weeks 3-8. Following anaesthesia, left renal sympathetic nerve activity was recorded, baroreflex gain curves were generated, by infusing phenylephrine and sodium nitroprusside, and cardiopulmonary baroreceptors challenged by infusing a saline load. RESULTS The high-fat diet elevated weight gain and adiposity index by 89 and 129% (both, P < 0.001). Mean blood pressure (132 ± 4 vs 103 ± 5 mmHg), fractional noradrenaline excretion and creatinine clearance (5.64 ± 0.55 vs 3.32 ± 0.35 mL min-1 kg-1 ) were 28, 77 and 69% higher (all P < 0.05), but urine flow and fractional sodium excretions were 42 and 72% (both P < 0.001) lower compared to normal rats. Plasma and renal TNF-α and IL-6 concentrations were fourfold to fivefold (P < 0.001) and 22 and 20% higher (both, P < 0.05), in obese rats but normalized following tacrolimus. In obese rats, baroreflex sensitivity was reduced by 80% (P < 0.05) but restored by renal denervation or tacrolimus. Volume expansion reduced renal sympathetic nerve activity by 54% (P < 0.001) in normal and obese rats subjected to renal denervation and tacrolimus, but not in obese rats with an intact renal innervation. CONCLUSION Obesity induced a renal inflammation and pointed to this being both the origin of autonomic dysregulation and a potential focus for targeted therapy.
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Affiliation(s)
- S. A. Khan
- Department of Physiology; School of Pharmaceutical Sciences; Universiti Sains Malaysia; Penang Malaysia
| | - M. Z. A. Sattar
- Department of Physiology; School of Pharmaceutical Sciences; Universiti Sains Malaysia; Penang Malaysia
| | - N. A. Abdullah
- Department of Pharmacology; Faculty of Medicine; Universiti Malaya; Kuala Lumpur Malaysia
| | - H. A. Rathore
- Department of Physiology; School of Pharmaceutical Sciences; Universiti Sains Malaysia; Penang Malaysia
| | - A. Ahmad
- Department of Pharmacology and Toxicology; School of Medicine; Virginia Commonwealth University; Richmond VA USA
| | - M. H. Abdulla
- Department of Physiology; University College Cork; Cork Ireland
| | - E. J. Johns
- Department of Physiology; University College Cork; Cork Ireland
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The role of brain angiotensin II (type 2) receptors and nitric oxide in the renal sympathoinhibitory response to acute volume expansion in conscious rats. J Hypertens 2017; 35:338-347. [PMID: 27820727 DOI: 10.1097/hjh.0000000000001154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE The study was performed to investigate the role of angiotensin II type 2 (AT2) receptors and nitric oxide in the renal sympathoinhibitory response to volume expansion (VEP). METHOD Conscious rats were subjected to volume expansion (VEP) [0.25% body weight/min saline for 10 min intravenously (i.v.)] following intracerebroventricular (i.c.v.) infusion of either saline or angiotensin II (Ang II), or a combination of Ang II with either losartan, PD123319, or N-nitro-L-arginine methyl ester (L-NAME). RESULTS Intracerebroventricular losartan, PD123319, or L-NAME did not change baseline mean arterial pressure, heart rate, or renal sympathetic nerve activity (RSNA). However, i.c.v. Ang II increased mean arterial pressure and decreased heart rate and RSNA baselines (113 ± 2 vs. 107 ± 2 mmHg, 365 ± 7 vs. 379 ± 5 beats/min, 1.03 ± 0.13 vs. 1.29 ± 0.15 μV.s, respectively, all P < 0.05). During i.c.v. saline infusion, VEP decreased RSNA by 27 ± 2% (P < 0.05) after 10 min and the magnitude of this response was unchanged during i.c.v. infusion of Ang II, losartan, or PD123319 but was decreased by L-NAME compared with that obtained with i.c.v. saline (14 ± 3 vs. 30 ± 5%, P < 0.05). i.c.v. Ang II in combination with losartan enhanced (41 ± 3 vs. 29 ± 5%) but with PD123319 decreased (15 ± 2 vs. 28 ± 4%, P < 0.05) the renal sympathoinhibition compared with Ang II alone. The renal sympathoinhibitory response was enhanced (43 ± 5 vs. 29 ± 1%, P < 0.05) by i.c.v. infusion of an AT2 agonist, CGP42112 the magnitude of which was unchanged when combined with L-NAME. The sympathoinhibitory response to VEP following Ang II plus L-NAME was similar to Ang II alone. CONCLUSION These findings suggest that activation of central AT2 receptors enhances the renal sympathoinhibitory response to VEP but this effect is not dependent on nitric oxide.
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Persson PB, Bondke Persson A. Hunger, craving and appetite. Acta Physiol (Oxf) 2017; 221:3-5. [PMID: 28703474 DOI: 10.1111/apha.12917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- P B Persson
- Corporate Member of Freie Universität Berlin, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Institute of Vegetative Physiology, Berlin, Germany
| | - A Bondke Persson
- Corporate Member of Freie Universität Berlin, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
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Abstract
Purpose of Review The etiology of hypertension, a critical public health issue affecting one in three US adults, involves the integration of the actions of multiple organ systems, including the renal sympathetic nerves. The renal sympathetic nerves, which are comprised of both afferent (sensory input) and efferent (sympathetic outflow) arms, have emerged as a major potential therapeutic target to treat hypertension and disease states exhibiting excess renal sympathetic activity. Recent Findings This review highlights recent advances in both clinical and basic science that have provided new insight into the distribution, function, and reinnervation of the renal sympathetic nerves, with a focus on the renal afferent nerves, in hypertension and hypertension-evoked disease states including salt-sensitive hypertension, obesity-induced hypertension, and chronic kidney disease. Summary Increased understanding of the differential role of the renal afferent versus efferent nerves in the pathophysiology of hypertension has the potential to identify novel targets and refine therapeutic interventions designed to treat hypertension.
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Abdulla MH, Johns EJ. The innervation of the kidney in renal injury and inflammation: a cause and consequence of deranged cardiovascular control. Acta Physiol (Oxf) 2017; 220:404-416. [PMID: 28181735 DOI: 10.1111/apha.12856] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/14/2016] [Accepted: 02/03/2017] [Indexed: 12/29/2022]
Abstract
Extensive investigations have revealed that renal sympathetic nerves regulate renin secretion, tubular fluid reabsorption and renal haemodynamics which can impact on cardiovascular homoeostasis normally and in pathophysiological states. The significance of the renal afferent innervation and its role in determining the autonomic control of the cardiovascular system is uncertain. The transduction pathways at the renal afferent nerves have been shown to require pro-inflammatory mediators and TRPV1 channels. Reno-renal reflexes have been described, both inhibitory and excitatory, demonstrating that a neural link exists between kidneys and may determine the distribution of excretory and haemodynamic function between the two kidneys. The impact of renal afferent nerve activity on basal and reflex regulation of global sympathetic drive remains opaque. There is clinical and experimental evidence that in states of chronic kidney disease and renal injury, there is infiltration of T-helper cells with a sympatho-excitation and blunting of the high- and low-pressure baroreceptor reflexes regulating renal sympathetic nerve activity. The baroreceptor deficits are renal nerve-dependent as the dysregulation can be relieved by renal denervation. There is also experimental evidence that in obese states, there is a sympatho-excitation and disrupted baroreflex regulation of renal sympathetic nerve activity which is mediated by the renal innervation. This body of information provides an important basis for directing greater attention to the role of renal injury/inflammation causing an inappropriate activation of the renal afferent nerves as an important initiator of aberrant autonomic cardiovascular control.
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Affiliation(s)
- M. H. Abdulla
- Department of Physiology; University College Cork; Cork Ireland
| | - E. J. Johns
- Department of Physiology; University College Cork; Cork Ireland
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Persson PB, Bondke Persson A. Altitude sickness and altitude adaptation. Acta Physiol (Oxf) 2017; 220:303-306. [PMID: 28498559 DOI: 10.1111/apha.12894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- P. B. Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin Berlin; Berlin Germany
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Persson PB. Announcing the $100 000 (one hundred thousand US Dollars) Acta Physiologica Award. Acta Physiol (Oxf) 2017; 220:7-8. [PMID: 28371179 DOI: 10.1111/apha.12880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- P. B. Persson
- Institut fuer vegetative Physiologie; Charité-Universitaetsmedizin; Berlin Germany
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Affiliation(s)
- R. Mrowka
- Klinik fuer Innere Medizin III; AG Experimentelle Nephrologie; Universitaetsklinikum Jena; Jena Germany
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28
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Affiliation(s)
- M. Ludwig
- Institut fuer Vegetative Physiologie; Charité Universitaetsmedizin Berlin; Berlin Germany
| | - A. Högner
- Institut fuer Vegetative Physiologie; Charité Universitaetsmedizin Berlin; Berlin Germany
| | - A. Patzak
- Institut fuer Vegetative Physiologie; Charité Universitaetsmedizin Berlin; Berlin Germany
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29
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Affiliation(s)
- R. Mrowka
- Experimentelle Nephrologie; Universitätsklinikum Jena, KIM III; Jena Germany
| | - S. Reuter
- Experimentelle Nephrologie; Universitätsklinikum Jena, KIM III; Jena Germany
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Huber DA, Schreihofer AM. Exaggerated sympathoexcitatory reflexes develop with changes in the rostral ventrolateral medulla in obese Zucker rats. Am J Physiol Regul Integr Comp Physiol 2016; 311:R243-53. [PMID: 27280427 DOI: 10.1152/ajpregu.00085.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/01/2016] [Indexed: 11/22/2022]
Abstract
Obesity leads to altered autonomic reflexes that reduce stability of mean arterial pressure (MAP). Sympathoinhibitory reflexes such as baroreflexes are impaired, but reflexes that raise MAP appear to be augmented. In obese Zucker rats (OZR) sciatic nerve stimulation evokes larger increases in MAP by unknown mechanisms. We sought to determine the autonomic underpinnings of this enhanced somatic pressor reflex and whether other sympathoexcitatory reflexes are augmented. We also determined whether their final common pathway, glutamatergic activation of the rostral ventrolateral medulla (RVLM), was enhanced in male OZR compared with lean Zucker rats (LZR). Sciatic nerve stimulation or activation of the nasopharyngeal reflex evoked larger rises in splanchnic sympathetic nerve activity (SNA) (79% and 45% larger in OZR, respectively; P < 0.05) and MAP in urethane-anesthetized, ventilated, paralyzed adult OZR compared with LZR. After elimination of baroreflex feedback by pharmacological prevention of changes in MAP and heart rate, these two sympathoexcitatory reflexes were still exaggerated in OZR (167% and 69% larger, respectively, P < 0.05). In adult OZR microinjections of glutamate, AMPA, or NMDA into the RVLM produced larger rises in SNA (∼61% larger in OZR, P < 0.05 for each drug) and MAP, but stimulation of axonal fibers in the upper thoracic spinal cord yielded equivalent responses in OZR and LZR. In juvenile OZR and LZR, sympathoexcitatory reflexes and physiological responses to RVLM activation were comparable. These data suggest that the ability of glutamate to activate the RVLM becomes enhanced in adult OZR and may contribute to the development of exaggerated sympathoexcitatory responses independent of impaired baroreflexes.
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Affiliation(s)
- Domitila A Huber
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas; and Department of Physiology, Medical College of Georgia,* Augusta, Georgia
| | - Ann M Schreihofer
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas; and Department of Physiology, Medical College of Georgia,* Augusta, Georgia
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31
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Affiliation(s)
- Pontus B. Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin Berlin; Berlin Germany
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Affiliation(s)
- R. G. Evans
- Department of Physiology; Monash University; Melbourne Vic. Australia
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