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Faitatzidou D, Karagiannidis AG, Theodorakopoulou MP, Xanthopoulos A, Triposkiadis F, Sarafidis PA. Autonomic Nervous System Dysfunction in Peritoneal Dialysis Patients: An Underrecognized Cardiovascular Risk Factor? Am J Nephrol 2023; 55:37-55. [PMID: 37788657 DOI: 10.1159/000534318] [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: 07/27/2023] [Accepted: 09/19/2023] [Indexed: 10/05/2023]
Abstract
BACKGROUND In patients with end-stage kidney disease (ESKD) receiving peritoneal dialysis (PD), cardiovascular events represent the predominant cause of morbidity and mortality, with cardiac arrhythmias and sudden death being the leading causes of death in this population. Autonomic nervous system (ANS) dysfunction is listed among the non-traditional risk factors accounting for the observed high cardiovascular burden, with a plethora of complex and not yet fully understood pathophysiologic mechanisms being involved. SUMMARY In recent years, preliminary studies have investigated and confirmed the presence of ANS dysfunction in PD patients, while relevant results from cohort studies have linked ANS dysfunction with adverse clinical outcomes in these patients. In light of these findings, ANS dysfunction has been recently receiving wider consideration as an independent cardiovascular risk factor in PD patients. The aim of this review was to describe the mechanisms involved in the pathogenesis of ANS dysfunction in ESKD and particularly PD patients and to summarize the existing studies evaluating ANS dysfunction in PD patients. KEY MESSAGES ANS dysfunction in PD patients is related to multiple complex mechanisms that impair the balance between SNS/PNS, and this disruption represents a crucial intermediator of cardiovascular morbidity and mortality in this population.
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Affiliation(s)
- Danai Faitatzidou
- First Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Artemios G Karagiannidis
- First Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Marieta P Theodorakopoulou
- First Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Filippos Triposkiadis
- Department of Cardiology, University Hospital of Larissa, Larissa, Greece
- School of Medicine, European University Cyprus, Nicosia, Cyprus
| | - Pantelis A Sarafidis
- First Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Zheng H, Katsurada K, Nandi S, Li Y, Patel KP. A Critical Role for the Paraventricular Nucleus of the Hypothalamus in the Regulation of the Volume Reflex in Normal and Various Cardiovascular Disease States. Curr Hypertens Rep 2022; 24:235-246. [PMID: 35384579 DOI: 10.1007/s11906-022-01187-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE OF REVIEW This review focuses on studies implicating forebrain neural pathways and neuromodulator systems, particularly, the nitric oxide system within the paraventricular nucleus of the hypothalamus in regulating neurohumoral drive, autonomic pathways, and fluid balance. RECENT FINDINGS Accumulating evidence from animals with experimental models of hypertension and heart failure as well as humans with hypertension suggests that alterations in central neural pathways, particularly, within the PVN neuromodulated by neuronal nitric oxide, are involved in regulating sympathetic outflow particularly to the kidney resulting in alterations in fluid balance commonly observed in hypertension and heart failure states. The characteristics of the hypertensive and heart failure states include alterations in neuronal nitric oxide within the PVN to cause an increase in renal sympathetic nerve activity to result in sodium and fluid retention in these diseases. A comprehensive understanding of these mechanisms will enhance our ability to treat hypertensive and heart failure conditions and their cardiovascular complications more efficiently.
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Affiliation(s)
- Hong Zheng
- Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, SD 57069, Vermillion, USA
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
| | - Shyam Nandi
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
| | - Yifan Li
- Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, SD 57069, Vermillion, USA
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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3
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Ahmad A. Physiological, Pathological and Pharmacological Interactions of Hydrogen Sulphide and Nitric Oxide in the Myocardium of Rats with Left Ventricular Hypertrophy. Curr Issues Mol Biol 2022; 44:433-448. [PMID: 35723409 PMCID: PMC8929131 DOI: 10.3390/cimb44010030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/07/2022] [Accepted: 01/08/2022] [Indexed: 11/16/2022] Open
Abstract
Left ventricular hypertrophy (LVH) is characterized by increased myocardium thickness due to increased oxidative stress and downregulation of cystathione γ lyase (CSE) endothelial nitric oxide synthase (eNOS). Upregulation of CSE by hydrogen sulphide (H2S) and ENOS by L-arginine can arrest the progression of LVH individually. The present study explored the combined treatment of H2S and NO in the progression of LVH, and demonstrated that the response is due to H2S, NO or formation of either new molecule in physiological, pathological, and pharmacological in vivo settings of LVH. Exogenous administration H2S+NO in LVH significantly reduced (all p < 0.05) systolic blood pressure (SBP) and mean arterial pressure (MAP), LV index, heart index and oxidative stress when compared to the LVH group. There was downregulation of CSE mRNA and eNOS in the heart, and exogenous administration of H2S+NO groups upregulated eNOS MRNA while CSE MRNA remained downregulated in the hearts of the LVH group. Similar trends were observed with concentrations of H2S and NO in the plasma and tissue. It can be concluded that combined treatment of LVH with H2S and NO significantly ameliorate the progression of LVH by attenuating systemic hemodynamic and physical indices, and by decreasing oxidative stress. Molecular expression data in the myocardium of LVH depicts that combined treatment upregulated eNOS/NO while it downregulated CSE/H2S pathways in in vivo settings, and it is always eNOS/NO pathways which play a major role.
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Affiliation(s)
- Ashfaq Ahmad
- Department of Pharmacy practice, College of Pharmacy, University of Hafr Al-Batin, Hafr Al-Batin 31991, Saudi Arabia
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4
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Hamaoka T, Blaha C, Luck JC, Leuenberger UA, Sinoway LI, Cui J. Acute effects of sublingual nitroglycerin on cardiovagal and sympathetic baroreflex sensitivity. Am J Physiol Regul Integr Comp Physiol 2021; 321:R525-R536. [PMID: 34378422 DOI: 10.1152/ajpregu.00304.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of nitroglycerin (glyceryl trinitrate, GTN) on baroreflex sensitivity (BRS) are incompletely understood. Moreover, there are no reports evaluating the acute responses in both the sympathetic BRS (SBRS) and the cardiovagal BRS (CBRS) to the administration of sublingual GTN. We hypothesized that sublingual GTN modulates both CBRS and SBRS. In 10 healthy subjects, beat-to-beat heart rate (HR), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) were recorded before and for 10 min after sublingual administration of GTN 0.4 mg. SBRS was evaluated from the relationship between spontaneous variations in diastolic BP and MSNA. CBRS was assessed with the sequence technique. These variables were assessed during baseline, during min 3rd - 6th (Post A) and 7th -10th min (Post B) after GTN administration. Two min after GTN administration, MSNA increased significantly and remained significantly elevated during recording. Compared to baseline, CBRS decreased significantly (Post A: 12.9 ± 1.6 to 7.1 ± 1.0 ms/mmHg, P < 0.05), while SBRS increased significantly (Post A: 0.8 ± 0.2 to 1.5 ± 0.2 units・beat-1・mmHg-1, P < 0.05) with an upward shift of the operating point. There were no differences in these variables between Post A and B. A clinical dose of GTN increased MSNA rapidly through effects on both CBRS and SBRS. These effects should be kept in mind when nitrates are used to clinically treat chest pain and acute coronary syndromes and used as vasodilators in experimental settings.
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Affiliation(s)
- Takuto Hamaoka
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Cheryl Blaha
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - J Carter Luck
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Urs A Leuenberger
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Lawrence I Sinoway
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Jian Cui
- Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, United States
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Hasan HF, Rashed LA, El Bakary NM. Concerted outcome of metformin and low dose of radiation in modulation of cisplatin induced uremic encephalopathy via renal and neural preservation. Life Sci 2021; 276:119429. [PMID: 33785333 DOI: 10.1016/j.lfs.2021.119429] [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: 02/03/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 10/21/2022]
Abstract
AIM The therapeutic expediency of cisplatin was limited due to its nephrotoxic side effects, so this study planned to assess the nephrotic and neuroprotective impact of metformin (MET) and low-dose radiation (LDR) in cisplatin-prompted kidney injury and uremic encephalopathy (UE). METHODS The effect of the 10-day MET treatment (200 mg/kg, orally) and/or fractionated LDR (0.25 Gy, of the total dose of 0.5 Gy, 1st and 7th day, respectively) on (5 mg/kg, intraperitoneally) cisplatin as a single dose was administered at the 5th day. Serum urea, creatinine and renal kidney injury molecule-1 were measured for the assessment of kidney function. Furthermore, the antioxidant potential in the renal and brain tissues was evaluated through, malondialdehyde and reduced glutathione estimation. Moreover, renal apoptotic markers: AMP-activated protein kinase, lipocalin, B-cell lymphoma 2 associated X protein, B-cell lymphoma 2, P53 and beclin 1 were estimated. UE was evaluated through the determination of serum inflammatory markers: nuclear factor kappa B, tumor-necrosis factor-α and interleukin 1 beta likewise, the cognitive deficits were assessed via forced swimming test, gamma-aminobutyric acid, n-methyl-d-aspartate and neuronal nitric oxide synthases besides AMP-activated protein kinase, light chain 3 and caspase3 levels in rats' cerebella. KEY FINDINGS The obtained results revealed a noticeable improvement in the previously mentioned biochemical factors and behavioral tasks that was reinforced by histopathological examination when using the present remedy. SIGNIFICANCE metformin and low doses of radiation afforded renoprotection and neuroprotection against cisplatin-induced acute uremic encephalopathy.
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Affiliation(s)
- Hesham Farouk Hasan
- Radiation Biology Department, National Center for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt.
| | - Laila A Rashed
- Department of Biochemistry, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Nermeen M El Bakary
- Radiation Biology Department, National Center for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt
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Agarwal R. Albuminuria and masked uncontrolled hypertension in chronic kidney disease. Nephrol Dial Transplant 2018; 32:2058-2065. [PMID: 27651468 DOI: 10.1093/ndt/gfw325] [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] [Received: 07/18/2016] [Accepted: 08/02/2016] [Indexed: 11/14/2022] Open
Abstract
Background Masked uncontrolled hypertension (MUCH) is associated with greater target organ damage such as left ventricular hypertrophy, increased arterial stiffness and albuminuria. Whether MUCH independently associates with greater cardiovascular end-organ damage or kidney damage is unclear. The objective of this study was to assess the strength of the relationship of MUCH (awake ambulatory blood pressure ≥135/85 mmHg and clinic blood pressure <140/90 mmHg) with target organ damage. Methods In a cross-sectional study at a veterans' administration medical center, clinically normotensive veterans without chronic kidney disease (CKD) (n = 29) and 287 patients with CKD and controlled hypertension (CH, n = 193), MUCH (n = 67) and uncontrolled hypertension (UCH, n = 27) had evaluation of target organ damage. Target organ damage was measured by echocardiography [left ventricular mass index (LVMI)], arterial ultrasonography [aortic pulse wave velocity (PWV)] and 24-h urine collection [albuminuria (urine albumin to creatinine ratio)] in all participants. Results Compared to that of controls, LVMI was higher by 21.8 g/m2 (CI, 4.0-39.7 g/m2) in CH, 27.9 (CI, 8-47.8) in MUCH and 39.5 (CI, 15.7-63.2) in UCH (P < 0.01 for group differences, P < 0.01 for linear trend). Although differences persisted after adjustment for age, sex and race, they lost significance after adjustments for cardiovascular risk factors and their treatment. Compared to that of controls, PWV was different among CH, MUCH and UCH (P = 0.04 for group differences, P = 0.02 for linear trend). However, differences lost significance after adjustments for age, sex and race. Compared to that of controls, log2 UACR was higher by 2.40 mg/mg (CI, 1.28-3.52) in CH, 4.94 (CI, 3.70-6.18) in MUCH and 6.01 (CI, 4.49-7.53) in UCH (P < 0.0001 for group difference, P < 0.0001 for linear trend). Differences persisted after adjustment for age, sex and race, cardiovascular risk factors and their treatment and cardiovascular disease (P < 0.0001 for group difference, P < 0.0001 for linear trend). Conclusions MUCH is more strongly related to albuminuria compared with cardiovascular damage as assessed by left ventricular mass and PWV. A graded and an independent relationship of blood pressure classification status with albuminuria is consistent with the hypothesis that renal mechanisms may be more important than cardiovascular disease in mediating the pathogenesis of MUCH.
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Affiliation(s)
- Rajiv Agarwal
- Department ofMedicine, Indiana University School of Medicine and Richard L. Roudebush Veterans Affairs AdministrationMedical Center, 1481 West 10th Street, Indianapolis, IN, USA
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7
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Yoon N, Na K, Kim HS. Simulated weightlessness affects the expression and activity of neuronal nitric oxide synthase in the rat brain. Oncotarget 2018; 8:30692-30699. [PMID: 28430607 PMCID: PMC5458159 DOI: 10.18632/oncotarget.15407] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 02/01/2017] [Indexed: 01/15/2023] Open
Abstract
Spaceflight induces pathophysiological alterations in various organs. To study pathophysiological adaptations to weightlessness on the ground, the tail suspension (TS) rat model has been used to simulate the effects of weightlessness. There is currently little information on the effect of TS on the expression and activity of nitric oxide synthase (NOS) in the brain. In this study, we examined time-dependent alterations in the expression and activity of neuronal NOS (nNOS) in the brains of TS rats. Male Sprague-Dawley rats were tail-suspended for 1 (TS1), 7 (TS7), and 14 (TS14) days or rested on the ground for 3 days after 14 days of TS. TS1 and TS7 rats exhibited no significant alterations in the expression of nNOS compared to control rats, whereas nNOS expression in TS14 rats was significantly upregulated compared to control rats. Normalized expression of nNOS mRNA and protein in TS14 rats (1.86 ± 0.48 and 1.84 ± 0.29, respectively) were significantly higher than that of control rats (P < 0.001 and P < 0.001, respectively). Consistent with these results, significant elevations in NOS activity and NO production were observed in TS14 rats. Thus, we demonstrated a significant upregulation of nNOS expression, accompanied by significant increases in NOS activity and NO production, in the brain of rats exposed to simulated weightlessness.
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Affiliation(s)
- Nara Yoon
- Department of Pathology, The Catholic University of Korea Incheon St. Mary's Hospital, Incheon, Republic of Korea
| | - Kiyong Na
- Department of Pathology, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hyun-Soo Kim
- Department of Pathology, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
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8
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Interaction between nitric oxide and renal α1-adrenoreceptors mediated vasoconstriction in rats with left ventricular hypertrophyin Wistar Kyoto rats. PLoS One 2018; 13:e0189386. [PMID: 29447158 PMCID: PMC5844246 DOI: 10.1371/journal.pone.0189386] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 11/26/2017] [Indexed: 01/19/2023] Open
Abstract
Left ventricular hypertrophy (LVH) is associated with decreased responsiveness of
renal α1-adrenoreceptors subtypes to adrenergic agonists. Nitric
oxide donors are known to have antihypertrophic effects however their impact on
responsiveness of renal α1-adrenoreceptors subtypes is unknown. This
study investigated the impact of nitric oxide (NO) and its potential interaction
with the responsiveness of renal α1-adrenoreceptors subtypes to
adrenergic stimulation in rats with left ventricular hypertrophy (LVH). This
study also explored the impact of NO donor on CSE expression in normal and LVH
kidney. LVH was induced using isoprenaline and caffeine in drinking water for 2
weeks while NO donor (L-arginine, 1.25g/Lin drinking water) was given for 5
weeks. Intrarenal noradrenaline, phenylephrine and methoxamine responses were
determined in the absence and presence of selective α1-adrenoceptor
antagonists, 5- methylurapidil (5-MeU), chloroethylclonidine (CeC) and BMY 7378.
Renal cortical endothelial nitric oxide synthase mRNA was upregulated 7 fold
while that of cystathione γ lyase was unaltered in the NO treated LVH rats
(LVH-NO) group compared to LVH group. The responsiveness of renal
α1A, α1B and α1D-adrenoceptors in the low dose
and high dose phases of 5-MeU, CEC and BMY7378 to adrenergic agonists was
increased along with cGMP in the kidney of LVH-NO group. These findings suggest
that exogenous NO precursor up-regulated the renal eNOS/NO/cGMP pathway in LVH
rats and resulted in augmented α1A, α1B and α1D
adrenoreceptors responsiveness to the adrenergic agonists. There is a positive
interaction between H2S and NO production in normal animals but this
interaction appears absent in LVH animals.
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9
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Jiang S, He H, Tan L, Wang L, Su Z, Liu Y, Zhu H, Zhang M, Hou FF, Li A. Proteomic and phosphoproteomic analysis of renal cortex in a salt-load rat model of advanced kidney damage. Sci Rep 2016; 6:35906. [PMID: 27775022 PMCID: PMC5075906 DOI: 10.1038/srep35906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 10/07/2016] [Indexed: 12/21/2022] Open
Abstract
Salt plays an essential role in the progression of chronic kidney disease and hypertension. However, the mechanisms underlying pathogenesis of salt-induced kidney damage remain largely unknown. Here, Sprague-Dawley rats, that underwent 5/6 nephrectomy (5/6Nx, a model of advanced kidney damage) or sham operation, were treated for 2 weeks with a normal or high-salt diet. We employed aTiO2 enrichment, iTRAQ labeling and liquid-chromatography tandem mass spectrometry strategy for proteomic and phosphoproteomic profiling of the renal cortex. We found 318 proteins differentially expressed in 5/6Nx group relative to sham group, and 310 proteins significantly changed in response to salt load in 5/6Nx animals. Totally, 1810 unique phosphopeptides corresponding to 550 phosphoproteins were identified. We identified 113 upregulated and 84 downregulated phosphopeptides in 5/6Nx animals relative to sham animals. Salt load induced 78 upregulated and 91 downregulated phosphopeptides in 5/6Nx rats. The differentially expressed phospholproteins are important transporters, structural molecules, and receptors. Protein-protein interaction analysis revealed that the differentially phosphorylated proteins in 5/6Nx group, Polr2a, Srrm1, Gsta2 and Pxn were the most linked. Salt-induced differential phosphoproteins, Myh6, Lmna and Des were the most linked. Altered phosphorylation levels of lamin A and phospholamban were validated. This study will provide new insight into pathogenetic mechanisms of chronic kidney disease and salt sensitivity.
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Affiliation(s)
- Shaoling Jiang
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hanchang He
- The First People's Foshan Hospital, Foshan, China
| | - Lishan Tan
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Liangliang Wang
- Division of Nephrology, First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, Guangzhou 510405, P.R. China
| | - Zhengxiu Su
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yufeng Liu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hongguo Zhu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Menghuan Zhang
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Fan Fan Hou
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Aiqing Li
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
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Chertok VM, Kotsyuba AE. The neurochemical features of intranuclear neurons of the medulla oblongata in normo- and hypertensive rats. NEUROCHEM J+ 2016. [DOI: 10.1134/s1819712416030053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Lin AM, Liao P, Millson EC, Quyyumi AA, Park J. Tetrahydrobiopterin ameliorates the exaggerated exercise pressor response in patients with chronic kidney disease: a randomized controlled trial. Am J Physiol Renal Physiol 2016; 310:F1016-25. [PMID: 26962106 PMCID: PMC5002055 DOI: 10.1152/ajprenal.00527.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/28/2016] [Indexed: 11/22/2022] Open
Abstract
Chronic kidney disease (CKD) patients have an exaggerated increase in blood pressure (BP) during rhythmic handgrip exercise (RHG 20%) and static handgrip exercise (SHG 30%). Nitric oxide levels increase during exercise and help prevent excessive hypertension by both increasing vasodilation and reducing sympathetic nerve activity (SNA). Therefore, we hypothesized that tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthase, would ameliorate the exaggerated exercise pressor response in CKD patients. In a randomized, double-blinded, placebo-controlled trial, we tested the effects of 12 wk of sapropterin dihydrochloride (6R-BH4; n = 18) versus placebo (n = 14) treatement on BP and muscle SNA (MSNA) responses during RHG 20% and SHG 30% in CKD patients. The 6R-BH4-treated group had a significantly lower systolic BP (+6 ± 1 vs. +13 ± 2 mmHg, P = 0.002) and mean arterial pressure response (+5 ± 1 vs. +10 ± 2 mmHg, P = 0.020) during RHG 20% and a significantly lower systolic BP response (+19 ± 3 vs. +28 ± 3 mmHg, P = 0.043) during SHG 30%. Under baseline conditions, there was no significant difference in MSNA responses between the groups; however, when the BP response during exercise was equalized between the groups using nitroprusside, the 6R-BH4-treated group had a significantly lower MSNA response during RHG 20% (6R-BH4 vs. placebo, +12 ± 1 vs. +21 ± 2 bursts/min, P = 0.004) but not during SHG 30%. These findings suggest that 6R-BH4 ameliorates the augmented BP response during RHG 20% and SHG 30% in CKD patients. A reduction in reflex activation of SNA may contribute to the decreased exercise pressor response during RHG 20% but not during SHG 30% in CKD patients.
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Affiliation(s)
- Ann M Lin
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Research Service Line, Department of Veterans Affairs Medical Center, Decatur, Georgia
| | - Peizhou Liao
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Erin C Millson
- Clinical Research Network, Atlanta Clinical and Translational Science Institute, Emory University School of Medicine, Atlanta, Georgia; and
| | - Arshed A Quyyumi
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Jeanie Park
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Research Service Line, Department of Veterans Affairs Medical Center, Decatur, Georgia;
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12
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Salman IM. Cardiovascular Autonomic Dysfunction in Chronic Kidney Disease: a Comprehensive Review. Curr Hypertens Rep 2016; 17:59. [PMID: 26071764 DOI: 10.1007/s11906-015-0571-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cardiovascular autonomic dysfunction is a major complication of chronic kidney disease (CKD), likely contributing to the high incidence of cardiovascular mortality in this patient population. In addition to adrenergic overdrive in affected individuals, clinical and experimental evidence now strongly indicates the presence of impaired reflex control of both sympathetic and parasympathetic outflow to the heart and vasculature. Although the principal underlying mechanisms are not completely understood, potential involvements of altered baroreceptor, cardiopulmonary, and chemoreceptor reflex function, along with factors including but not limited to increased renin-angiotensin-aldosterone system activity, activation of the renal afferents and cardiovascular structural remodeling have been suggested. This review therefore analyzes potential mechanisms underpinning autonomic imbalance in CKD, covers results accumulated thus far on cardiovascular autonomic function studies in clinical and experimental renal failure, discusses the role of current interventional and therapeutic strategies in ameliorating autonomic deficits associated with chronic renal dysfunction, and identifies gaps in our knowledge of neural mechanisms driving cardiovascular disease in CKD.
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Affiliation(s)
- Ibrahim M Salman
- The Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia,
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13
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Park J, Liao P, Sher S, Lyles RH, Deveaux DD, Quyyumi AA. Tetrahydrobiopterin lowers muscle sympathetic nerve activity and improves augmentation index in patients with chronic kidney disease. Am J Physiol Regul Integr Comp Physiol 2015; 308:R208-18. [PMID: 25477424 PMCID: PMC4313073 DOI: 10.1152/ajpregu.00409.2014] [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: 09/26/2014] [Accepted: 12/01/2014] [Indexed: 11/22/2022]
Abstract
Chronic kidney disease (CKD) is characterized by overactivation of the sympathetic nervous system (SNS) that contributes to cardiovascular risk. Decreased nitric oxide (NO) bioavailability is a major factor contributing to SNS overactivity in CKD, since reduced neuronal NO leads to increased central SNS activity. Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide synthase that increases NO bioavailability in experimental models of CKD. We conducted a randomized, double-blinded, placebo-controlled trial testing the benefits of oral sapropterin dihydrochloride (6R-BH4, a synthetic form of BH4) in CKD. 36 patients with CKD and hypertension were randomized to 12 wk of 1) 200 mg 6R-BH4 twice daily + 1 mg folic acid once daily; vs. 2) placebo + folic acid. The primary endpoint was a change in resting muscle sympathetic nerve activity (MSNA). Secondary endpoints included arterial stiffness using pulse wave velocity (PWV) and augmentation index (AIx), endothelial function using brachial artery flow-mediated dilation and endothelial progenitor cells, endothelium-independent vasodilatation (EID), microalbuminuria, and blood pressure. We observed a significant reduction in MSNA after 12 wk of 6R-BH4 (-7.5 ± 2.1 bursts/min vs. +3.2 ± 1.3 bursts/min; P = 0.003). We also observed a significant improvement in AIx (by -5.8 ± 2.0% vs. +1.8 ± 1.7 in the placebo group, P = 0.007). EID increased significantly (by +2.0 ± 0.59%; P = 0.004) in the 6R-BH4 group, but there was no change in endothelial function. There was a trend toward a reduction in diastolic blood pressure by -4 ± 3 mmHg at 12 wk with 6R-BH4 (P = 0.055). 6R-BH4 treatment may have beneficial effects on SNS activity and central pulse wave reflections in hypertensive patients with CKD.
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Affiliation(s)
- Jeanie Park
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Research Service Line, Department of Veterans Affairs Medical Center, Decatur, Georgia;
| | - Peizhou Liao
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia; and
| | - Salman Sher
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Robert H Lyles
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia; and
| | - Don D Deveaux
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Research Service Line, Department of Veterans Affairs Medical Center, Decatur, Georgia
| | - Arshed A Quyyumi
- Cardiology Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
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Branco LG, Soriano RN, Steiner AA. Gaseous Mediators in Temperature Regulation. Compr Physiol 2014; 4:1301-38. [DOI: 10.1002/cphy.c130053] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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15
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Fujisaki K, Tsuruya K, Yamato M, Toyonaga J, Noguchi H, Nakano T, Taniguchi M, Tokumoto M, Hirakata H, Kitazono T. Cerebral oxidative stress induces spatial working memory dysfunction in uremic mice: neuroprotective effect of tempol. Nephrol Dial Transplant 2014; 29:529-538. [DOI: 10.1093/ndt/gft327] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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Campese VM, Ye S. A vitamin-E-fortified diet reduces oxidative stress, sympathetic nerve activity, and hypertension in the phenol-renal injury model in rats. ACTA ACUST UNITED AC 2012; 1:242-50. [PMID: 20409856 DOI: 10.1016/j.jash.2007.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 04/19/2007] [Accepted: 04/20/2007] [Indexed: 02/07/2023]
Abstract
Renal injury caused by the injection of phenol in the lower pole of one kidney increases sympathetic nervous system (SNS) activity and blood pressure (BP), and these effects are mediated by increased reactive oxygen species (ROS) in brain nuclei involved in the noradrenergic control of BP. This suggests that therapy with antioxidants might be beneficial in this model. In this study, we tested the hypothesis that a vitamin (Vit)-E-enriched diet might decrease oxidative stress in the brain and result in reduced SNS activity and BP in animals with phenol-renal injury. To this end, we examined the effects of a Vit-E-fortified diet vs. a control diet on BP, norepinephrine (NE) secretion from the posterior hypothalamic nuclei (PH), and the abundance of several components of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase in the brain of rats with phenol-induced renal injury. A Vit-E-fortified diet mitigated the formation of ROS in the brain, and this was associated with reduced SNS activity and BP in rats with phenol-induced renal injury. In conclusion, antioxidants appear to be beneficial in the management of hypertension caused by renal injury and increased SNS activity.
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Affiliation(s)
- Vito M Campese
- Division of Nephrology; and the Hypertension Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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17
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Lameu C, Trujillo CA, Schwindt TT, Negraes PD, Pillat MM, Morais KLP, Lebrun I, Ulrich H. Interactions between the NO-citrulline cycle and brain-derived neurotrophic factor in differentiation of neural stem cells. J Biol Chem 2012; 287:29690-701. [PMID: 22730318 DOI: 10.1074/jbc.m111.338095] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The diffusible messenger NO plays multiple roles in neuroprotection, neurodegeneration, and brain plasticity. Argininosuccinate synthase (AS) is a ubiquitous enzyme in mammals and the key enzyme of the NO-citrulline cycle, because it provides the substrate L-arginine for subsequent NO synthesis by inducible, endothelial, and neuronal NO synthase (NOS). Here, we provide evidence for the participation of AS and of the NO-citrulline cycle in the progress of differentiation of neural stem cells (NSC) into neurons, astrocytes, and oligodendrocytes. AS expression and activity and neuronal NOS expression, as well as l-arginine and NO(x) production, increased along neural differentiation, whereas endothelial NOS expression was augmented in conditions of chronic NOS inhibition during differentiation, indicating that this NOS isoform is amenable to modulation by extracellular cues. AS and NOS inhibition caused a delay in the progress of neural differentiation, as suggested by the decreased percentage of terminally differentiated cells. On the other hand, BDNF reversed the delay of neural differentiation of NSC caused by inhibition of NO(x) production. A likely cause is the lack of NO, which up-regulated p75 neurotrophin receptor expression, a receptor required for BDNF-induced differentiation of NSC. We conclude that the NO-citrulline cycle acts together with BDNF for maintaining the progress of neural differentiation.
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Affiliation(s)
- Claudiana Lameu
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, 05508-900 São Paulo, Brazil
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Northcott CA, Billecke S, Craig T, Hinojosa-Laborde C, Patel KP, Chen AF, D'Alecy LG, Haywood JR. Nitric oxide synthase, ADMA, SDMA, and nitric oxide activity in the paraventricular nucleus throughout the etiology of renal wrap hypertension. Am J Physiol Heart Circ Physiol 2012; 302:H2276-84. [PMID: 22447945 DOI: 10.1152/ajpheart.00562.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Within the paraventricular nucleus (PVN), there is a balance between the excitatory and inhibitory neurotransmitters that regulate blood pressure; in hypertension, the balance shifts to enhanced excitation. Nitric oxide (NO) is an atypical neurotransmitter that elicits inhibitory effects on cardiovascular function. We hypothesized that reduced PVN NO led to elevations in blood pressure during both the onset and sustained phases of hypertension due to decreased NO synthase (NOS) and increased asymmetrical dimethylarginine (ADMA; an endogenous NOS inhibitor) and symmetric dimethylarginine (SDMA). Elevated blood pressure, in response to PVN bilateral microinjections of a NO inhibitor, nitro-L-arginine methyl ester, was blunted in renal wrapped rats during the onset of hypertension (day 7) and sustained renal wrap hypertension (day 28) compared with sham-operated rats. Adenoviruses (Ad) encoding endothelial NOS (eNOS) or LacZ microinjected into the PVN [1 × 10(9) plaque-forming units, bilateral (200 nl/site)] reduced mean arterial pressure compared with control (Day 7, Ad LacZ wrap: 144 ± 7 mmHg and Ad eNOS wrap: 117 ± 5 mmHg, P ≤ 0.05) throughout the study (Day 28, Ad LacZ wrap: 123 ± 1 mmHg and Ad eNOS wrap: 108 ± 4 mmHg, P ≤ 0.05). Western blot analyses of PVN NOS revealed significantly lower PVN neuronal NOS during the onset of hypertension but not in sustained hypertension. Reduced SDMA was found in the PVN during the onset of hypertension; however, no change in ADMA was observed. In conclusion, functional indexes of NO activity indicated an overall downregulation of NO in renal wrap hypertension, but the mechanism by which this occurs likely differs throughout the development of hypertension.
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Affiliation(s)
- Carrie A Northcott
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, 48824, USA
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19
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Soriano R, Kwiatkoski M, Batalhao M, Branco L, Carnio E. Interaction between the carbon monoxide and nitric oxide pathways in the locus coeruleus during fever. Neuroscience 2012; 206:69-80. [DOI: 10.1016/j.neuroscience.2012.01.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 12/06/2011] [Accepted: 01/07/2012] [Indexed: 10/14/2022]
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Campos RR, Oliveira-Sales EB, Nishi EE, Boim MA, Dolnikoff MS, Bergamaschi CT. The role of oxidative stress in renovascular hypertension. Clin Exp Pharmacol Physiol 2011; 38:144-52. [PMID: 20678153 DOI: 10.1111/j.1440-1681.2010.05437.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
1. There is mounting evidence that increased oxidative stress and sympathetic nerve activity play important roles in renovascular hypertension. In the present review, we focus on the importance of oxidative stress in two distinct populations of neurons involved with cardiovascular regulation: those of the rostral ventrolateral medulla (RVLM) and those of the paraventricular nucleus of the hypothalamus (PVN) in the maintenance of sympathoexcitation and hypertension in two kidney-one clip (2K1C) hypertensive rats. Furthermore, the role of oxidative stress in the clipped kidney is also discussed. 2. In the studies reviewed in this article, it was found that hypertension and renal sympathoexcitation in 2K1C rats were associated with an increase in Angiotensin II type one receptor (AT(1) ) expression and in oxidative markers within the RVLM, PVN and in the clipped kidneys of 2K1C rats. Furthermore, acute or chronic anti-oxidant treatment decreased blood pressure and sympathetic activity, and improved the baroreflex control of heart rate and renal sympathetic nerve activity in 2K1C rats. Tempol or vitamin C administration in the RVLM, PVN or systemically all reduced blood pressure and renal sympathetic activity. Cardiovascular improvement in response to chronic anti-oxidant treatment was associated with a downregulation of AT(1) receptors, as well as oxidative markers in the central nuclei and clipped kidney. 3. The data discussed in the present review support the idea that an increase in oxidative stress within the RVLM, PVN and in the ischaemic kidney plays a major role in the maintenance of sympathoexcitation and hypertension in 2K1C rats.
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Affiliation(s)
- Ruy R Campos
- Department of Physiology, Cardiovascular Division Department of Medicine, Nephrology Division, Federal University of São Paulo, São Paulo, Brazil.
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Campese VM, Ku E, Park J. Sympathetic renal innervation and resistant hypertension. Int J Hypertens 2011; 2011:814354. [PMID: 21331158 PMCID: PMC3034934 DOI: 10.4061/2011/814354] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 11/01/2010] [Indexed: 01/09/2023] Open
Abstract
Hypertension in chronic renal disease and renovascular disease is often resistant to therapy. Understanding the pathogenic mechanisms responsible for hypertension in these conditions may lead to improved and more targeted therapeutic interventions. Several factors have been implicated in the pathogenesis of hypertension associated with renal disease and/or renal failure. Although the role of sodium retention, total body volume expansion, and hyperactivity of the renin-angiotensin-aldosterone system (RAAS) are well recognized, increasing evidence suggests that afferent impulses from the injured kidney may increase sympathetic nervous system activity in areas of the brain involved in noradrenergic regulation of blood pressure and contribute to the development and maintenance of hypertension associated with kidney disease. Recognition of this important pathogenic factor suggests that antiadrenergic drugs should be an essential component to the management of hypertension in patients with kidney disease, particularly those who are resistant to other modalities of therapy.
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Affiliation(s)
- Vito M Campese
- Division of Nephrology, USC/Keck School of Medicine, University of Southern California, 2020 Zonal Aveue, Los Angeles, CA 90033, USA
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Reis WL, Saad WA, Camargo LA, Elias LL, Antunes-Rodrigues J. Central nitrergic system regulation of neuroendocrine secretion, fluid intake and blood pressure induced by angiotensin-II. Behav Brain Funct 2010; 6:64. [PMID: 20974001 PMCID: PMC2987978 DOI: 10.1186/1744-9081-6-64] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 10/25/2010] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Nitric oxide (NO) synthesis has been described in several circumventricular and hypothalamic structures in the central nervous system that are implicated in mediating central angiotensin-II (ANG-II) actions during water deprivation and hypovolemia. Neuroendocrine and cardiovascular responses, drinking behavior, and urinary excretions were examined following central angiotensinergic stimulation in awake freely-moving rats pretreated with intracerebroventricular injections of Nω-nitro-L-arginine methyl ester (L-NAME, 40 μg), an inhibitor of NO synthase, and L-arginine (20 ug), a precursor of NO. RESULTS Injections of L-NAME or ANG-II produced an increase in plasma vasopressin (VP), oxytocin (OT) and atrial natriuretic peptide (ANP) levels, an increase in water and sodium intake, mean arterial blood pressure and sodium excretion, and a reduction of urinary volume. L-NAME pretreatment enhanced the ANG-II response, while L-arginine attenuated VP and OT release, thirst, appetite for sodium, antidiuresis, and natriuresis, as well as pressor responses induced by ANG-II. DISCUSSION AND CONCLUSION Thus, the central nitrergic system participates in the angiotensinergic responses evoked by water deprivation and hypovolemia to refrain neurohypophysial secretion, hydromineral balance, and blood pressure homeostasis.
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Affiliation(s)
- Wagner L Reis
- Department of Physiology, School of Dentistry, Paulista State University of Araraquara, UNESP Araraquara São Paulo, Brazil
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Rossi NF, Maliszewska-Scislo M, Chen H, Black SM, Sharma S, Ravikov R, Augustyniak RA. Neuronal nitric oxide synthase within paraventricular nucleus: blood pressure and baroreflex in two-kidney, one-clip hypertensive rats. Exp Physiol 2010; 95:845-57. [PMID: 20494920 DOI: 10.1113/expphysiol.2009.051789] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The renin-angiotensin system is activated in the early phase of two-kidney, one-clip (2K-1C) hypertension. The paraventricular nucleus (PVN) integrates inputs regulating sympathetic outflow. The PVN receives inputs from plasma angiotensin II via projections from circumventricular organs and from renal afferent nerves transmitted via the nucleus tractus solitarii. Nitric oxide within the PVN may exert a sympathoinhibitory effect. These studies tested whether decreasing endogenous nitric oxide by introducing dominant negative (DN) constructs for neuronal nitric oxide synthase (nNOS) into PVN chronically augments hypertension and/or modulates baroreflex function. Male 6-week-old Sprague-Dawley rats underwent sham surgery or right renal artery clipping and placement of radiotelemetry transmitters. One week later, the PVN was injected bilaterally with 250 nl artificial cerebrospinal fluid containing 250 ng microl(-1) of RSV beta-galactosidase (beta-Gal), cytomegalovirus (CMV) wild-type (WT nNOS), or respiratory syncytial virus (RSV) haeme domain or RSV haemeRedF (DN nNOS). Haemodynamics were monitored for 5 weeks. Then left renal nerve electrodes were placed, and 2 days later the rats underwent baroreflex testing in the conscious state. The rise in mean arterial pressure (MAP) was significantly potentiated in the DN nNOS 2K-1C group beyond 15 days after PVN injection. By day 35, MAP in the 2K-1C groups was 152 +/- 6.3 (beta-Gal), 155.1 +/- 6.6 (WT nNOS) and 179 +/- 5.4 mmHg (DN nNOS; P < 0.01 versus all other groups). Sham-clipped rats remained normotensive. All groups displayed progressive bradycardia over time that was attenuated in the DN nNOS 2K-1C group. Baroreflex curves shifted to higher pressures, and baroreflex sensitivity of heart rate was diminished to a similar extent in all groups of 2K-1C rats. The baroreflex response of renal sympathetic nerve activity was preserved. The PVN tissue from DN nNOS rats had decreased dimerization of nNOS and generation of total nitric oxide. These findings indicate that chronic interference of nNOS dimerization required for generation of nitric oxide within the PVN potentiates the increase of blood pressure by modulating the sympathoexcitation that accompanies renovascular hypertension.
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Affiliation(s)
- Noreen F Rossi
- Department of Internal Medicine, Wayne State University School of Medicine, 4160 John R. Street, no. 908, Detroit, MI 48201, USA.
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Chronic antioxidant treatment improves arterial renovascular hypertension and oxidative stress markers in the kidney in Wistar rats. Am J Hypertens 2010; 23:473-80. [PMID: 20186128 DOI: 10.1038/ajh.2010.11] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Sympathetic vasomotor hyperactivity and baroreflex dysfunction are involved in the development and maintenance of renovascular arterial hypertension. We hypothesized that angiotensin (Ang) II-dependent oxidative stress contributes to the pathophysiology of the two-kidney, one-clip (2K-1C) model. METHODS The mean arterial pressure (MAP), baroreflex, and renal sympathetic nerve activity (rSNA) were evaluated after chronic administration of an antioxidant, vitamin C (vitC 150 mg/kg/day) in male Wistar 2K-1C rats. Additionally, the mRNA levels of Ang II subtype 1 receptor (AT(1)R), NAD(P)H oxidase subunits (p47phox and gp91phox), and major antioxidant enzymes were evaluated in the renal cortex. RESULTS After vitC treatment, the MAP (170 +/- 4 vs. 133 +/- 6 mm Hg; P < 0.05) and rSNA (161 +/- 5 vs. 118 +/- 12 spikes/s; P < 0.05) were significantly reduced only in the 2K-1C group. VitC improved the baroreflex control of heart rate (HR) and rSNA. The expression of AT(1)R, p47phox, and gp91phox was elevated (51, 184, and 132%, respectively) in the clipped kidney of 2K-1C group. VitC downregulated AT(1)R in the clipped kidney (31%). Catalase (CAT) expression was reduced in clipped (70%) and nonclipped (83%) kidneys of 2K-1C rats. VitC treatment augmented the expression of glutathione peroxidase (GPx) in both clipped (185%) and nonclipped (212%) kidneys of the 2K-1C group. CONCLUSIONS The present study suggests a role for oxidative stress in the cardiovascular and sympathetic alterations in renovascular hypertension, associated with changes in the expression of AT(1)R, NAD(P)H oxidase subunits, and antioxidant enzymes in the kidney.
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Soriano RN, Ravanelli MI, Batalhao ME, Carnio EC, Branco LGS. Propyretic role of the locus coeruleus nitric oxide pathway. Exp Physiol 2010; 95:669-77. [PMID: 20176679 DOI: 10.1113/expphysiol.2009.051490] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nitric oxide has been reported to modulate fever in the brain. However, the sites where NO exerts this modulation remain somewhat unclear. Locus coeruleus (LC) neurons express not only nitric oxide synthase (NOS) but also soluble guanylyl cyclase (sGC). In the present study, we evaluated in vivo and ex vivo the putative role of the LC NO-cGMP pathway in fever. To this end, deep body temperature was measured before and after pharmacological modulations of the pathway. Moreover, nitrite/nitrate (NOx) and cGMP levels in the LC were assessed. Conscious rats were microinjected within the LC with a non-selective NOS inhibitor (N(G)-monomethyl-l-arginine acetate), a NO donor (NOC12), a sGC inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) or a cGMP analogue (8-bromo-cGMP) and injected intraperitoneally with endotoxin. Inhibition of NOS or sGC before endotoxin injection significantly increased the latency to the onset of fever. During the course of fever, inhibition of NOS or sGC attenuated the febrile response, whereas microinjection of NOC12 or 8-bromo-cGMP increased the response. These findings indicate that the LC NO-cGMP pathway plays a propyretic role. Furthermore, we observed a significant increase in NOx and cGMP levels, indicating that the febrile response to endotoxin is accompanied by stimulation of the NO-cGMP pathway in the LC.
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Affiliation(s)
- Renato N Soriano
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900 - Ribeirão Preto, SP, Brazil.
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Control of systemic and pulmonary blood pressure by nitric oxide formed through neuronal nitric oxide synthase. J Hypertens 2010; 27:1929-40. [PMID: 19587610 DOI: 10.1097/hjh.0b013e32832e8ddf] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nitric oxide formed by neuronal nitric oxide synthase (nNOS) in the brain, autonomic inhibitory (nitrergic) nerves, and heart plays important roles in the control of blood pressure. Activation of nitrergic nerves innervating the systemic vasculature elicits vasodilatation, decreases peripheral resistance, and lowers blood pressure. Impairment of nitrergic nerve function, as well as endothelial dysfunction, results in systemic and pulmonary hypertension and decreased regional blood flow. Blockade of nNOS activity in the brain, particularly the medulla and hypothalamus, causes systemic hypertension. Under hypertensive states, such as those in spontaneously hypertensive and Dahl salt-sensitive rats, the expression of the nNOS gene in the brain is increased; this appears to counteract the activated sympathetic function in the vasomotor center. The present article summarizes information concerning the modulation of systemic and pulmonary hypertension through nNOS-derived nitric oxide produced in the brain and periphery.
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Xue B, Singh M, Guo F, Hay M, Johnson AK. Protective actions of estrogen on angiotensin II-induced hypertension: role of central nitric oxide. Am J Physiol Heart Circ Physiol 2009; 297:H1638-46. [PMID: 19734362 DOI: 10.1152/ajpheart.00502.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study tested the hypotheses that 1) nitric oxide (NO) is involved in attenuated responses to ANG II in female mice, and 2) there is differential expression of neuronal NO synthase (nNOS) in the subfornical organ (SFO) and paraventricular nucleus (PVN) in response to systemic infusions of ANG II in males vs. females. Aortic blood pressure (BP) was measured in conscious mice with telemetry implants. N(G)-nitro-l-arginine methyl ester (l-NAME; 100 microg x kg(.-1)day(-1)), an inhibitor of NOS, was administrated into the lateral cerebral ventricle for 14 days before and during ANG II pump implantation. Central infusion of l-NAME augmented the pressor effects of systemic ANG II in females (Delta21.5 + or - 2.2 vs. Delta9.2 + or - 1.5 mmHg) but not in males (Delta29.4 + or - 2.5 vs. Delta30.1 + or - 2.5 mmHg). Central administration of N(5)-(1-imino-3-butenyl)-l-ornithine (l-VNIO), a selective nNOS inhibitor, also significantly potentiated the increase in BP induced by ANG II in females (Delta17.5 + or - 3.2 vs. Delta9.2 + or - 1.5 mmHg). In gonadectomized mice, central l-NAME infusion did not affect the pressor response to ANG II in either males or females. Ganglionic blockade after ANG II infusion resulted in a greater reduction in BP in central l-NAME- or l-VNIO-treated females compared with control females. Western blot analysis of nNOS protein expression indicated that levels were approximately 12-fold higher in both the SFO and PVN of intact females compared with those in intact males. Seven days of ANG II treatment resulted in a further increase in nNOS protein expression only in intact females (PVN, to approximately 51-fold). Immunohistochemical studies revealed colocalization of nNOS and estrogen receptors in the SFO and PVN. These results suggest that NO attenuates the increase in BP induced by ANG II through reduced sympathetic outflow in females and that increased nNOS protein expression associated with the presence of female sex hormones plays a protective role against ANG II-induced hypertension in female mice.
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Affiliation(s)
- Baojian Xue
- Department of Psychology, University of Iowa, 11 Seashore Hall E, Iowa City, IA 52242, USA.
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Zhang L, Tong M, Xiao M, Li L, Ding J. Nitric oxide mediates feedback inhibition in angiotensin II-induced upregulation of vasopressin mRNA. Peptides 2009; 30:913-7. [PMID: 19428769 DOI: 10.1016/j.peptides.2009.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 01/25/2009] [Accepted: 01/26/2009] [Indexed: 11/30/2022]
Abstract
Angiotensin II (Ang II) stimulates hypothalamic magnocellular neurons to release arginine vasopressin (AVP) via Ang II type 1 (AT1) receptors during chronic hyperosmotic condition. On the other hand, endogenous nitric oxide (NO) tonically inhibits the activity of AVP producing neurons; and system infusion of Ang II elicits the activity of NO producing neurons in the hypothalamus. These studies suggest that NO may mediate feedback inhibition in Ang II modulation of AVP neuronal excitability. To confirm this hypothesis, we first investigated colocalization of neuronal NO synthase (nNOS) and AT1 receptors in the hypothalamic magnocellular nuclei of adult male rats by using double immunofluorescence. We found that 60% and 65% of AT1 receptors immunoreactive neurons coexpressed nNOS in the hypothalamic paraventricular nucleus and supraoptic nucleus, respectively. We then demonstrated that intracerebroventricular administration of nNOS inhibitor N-omega-nitro-l-arginine methyl ester further enhanced upregulation of AVP mRNA level but totally abolished upregulation of nNOS mRNA level in the paraventricular and supraoptic nuclei of anesthetized rats induced by a prior administration of Ang II. Theses morphological and pharmacological data demonstrate that NO mediates negative feedback regulation of Ang II-induced upregulation of AVP mRNA.
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Affiliation(s)
- Luqing Zhang
- Department of Anatomy, Histology & Embryology, Nanjing Medical University, Nanjing, Jiangsu, PR China
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Gwathmey TM, Shaltout HA, Pendergrass KD, Pirro NT, Figueroa JP, Rose JC, Diz DI, Chappell MC. Nuclear angiotensin II type 2 (AT2) receptors are functionally linked to nitric oxide production. Am J Physiol Renal Physiol 2009; 296:F1484-93. [PMID: 19244399 DOI: 10.1152/ajprenal.90766.2008] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Expression of nuclear angiotensin II type 1 (AT(1)) receptors in rat kidney provides further support for the concept of an intracellular renin-angiotensin system. Thus we examined the cellular distribution of renal ANG II receptors in sheep to determine the existence and functional roles of intracellular ANG receptors in higher order species. Receptor binding was performed using the nonselective ANG II antagonist (125)I-[Sar(1),Thr(8)]-ANG II ((125)I-sarthran) with the AT(1) antagonist losartan (LOS) or the AT(2) antagonist PD123319 (PD) in isolated nuclei (NUC) and plasma membrane (PM) fractions obtained by differential centrifugation or density gradient separation. In both fetal and adult sheep kidney, PD competed for the majority of cortical NUC (> or =70%) and PM (> or =80%) sites while LOS competition predominated in medullary NUC (> or =75%) and PM (> or =70%). Immunodetection with an AT(2) antibody revealed a single approximately 42-kDa band in both NUC and PM extracts, suggesting a mature molecular form of the NUC receptor. Autoradiography for receptor subtypes localized AT(2) in the tubulointerstitium, AT(1) in the medulla and vasa recta, and both AT(1) and AT(2) in glomeruli. Loading of NUC with the fluorescent nitric oxide (NO) detector DAF showed increased NO production with ANG II (1 nM), which was abolished by PD and N-nitro-l-arginine methyl ester, but not LOS. Our studies demonstrate ANG II receptor subtypes are differentially expressed in ovine kidney, while nuclear AT(2) receptors are functionally linked to NO production. These findings provide further evidence of a functional intracellular renin-angiotensin system within the kidney, which may represent a therapeutic target for the regulation of blood pressure.
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Affiliation(s)
- Tanya M Gwathmey
- Hypertension and Vascular Research Center, Wake Forest Univ. School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA.
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Bai Y, Jabbari B, Ye S, Campese VM, Vaziri ND. Regional expression of NAD(P)H oxidase and superoxide dismutase in the brain of rats with neurogenic hypertension. Am J Nephrol 2008; 29:483-92. [PMID: 19047792 DOI: 10.1159/000178817] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Accepted: 09/29/2008] [Indexed: 01/28/2023]
Abstract
BACKGROUND Single injection of small quantities of phenol into the kidney cortex causes hypertension which is mediated by renal afferent sympathetic pathway activation. This phenomenon can be prevented by superoxide dismutase (SOD) infusion in the lateral ventricle, suggesting the role of superoxide (O(2)(-).) in noradrenergic control of arterial pressure. Since NAD(P)H oxidase is a major source of O(2)(-)., we tested the hypothesis that hypertension in this model may be associated with upregulation of NAD(P)H oxidase in relevant regions of brain. METHODS NAD(P)H oxidase subunits, mitochondrial (MnSOD) and cytoplasmic (CuZnSOD) SOD were measured in rats 4 weeks after injection of phenol or saline in the left kidney cortex. RESULTS Phenol-injected rats exhibited hypertension, upregulation of gp91(phox), p22(phox), p47(phox) and p67(phox) in the medulla, gp91(phox) and p22(phox) in pons and gp91(phox) in hypothalamus. This was associated with upregulation of MnSOD with little change in CuZnSOD. CONCLUSIONS Chronic hypertension in phenol-injected rats is associated with upregulation of NAD(P)H oxidase and hence increased O(2)(-). production capacity in the key regions of the brain involved in regulation of blood pressure. Since reactive oxygen species can intensify central noradrenergic activity, the observed maladaptive changes may contribute to the genesis and maintenance of the associated hypertension.
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Affiliation(s)
- Yongli Bai
- Division of Nephrology and Hypertension, University of California-Irvine, 101 The City Drive, Orange, CA 92868, USA
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Schlaich MP, Socratous F, Hennebry S, Eikelis N, Lambert EA, Straznicky N, Esler MD, Lambert GW. Sympathetic activation in chronic renal failure. J Am Soc Nephrol 2008; 20:933-9. [PMID: 18799718 DOI: 10.1681/asn.2008040402] [Citation(s) in RCA: 304] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The potential involvement of sympathetic overactivity has been neglected in this population despite accumulating experimental and clinical evidence suggesting a crucial role of sympathetic activation for both progression of renal failure and the high rate of cardiovascular events in patients with chronic kidney disease. The contribution of sympathetic neural mechanisms to the occurrence of cardiac arrhythmias, the development of hypertension, and the progression of heart failure are well established; however, the exact mechanisms contributing to heightened sympathetic tone in patients with chronic kidney disease are unclear. This review analyses potential mechanisms underlying sympathetic activation in chronic kidney disease, the range of adverse consequences associated with this activation, and potential therapeutic implications resulting from this relationship.
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Affiliation(s)
- Markus P Schlaich
- Neurovascular Hypertension & Kidney Disease Laboratory, Baker Heart Research Institute, P.O. Box 6492 St. Kilda Road Central, Melbourne VIC 8008, Australia.
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Torrecilla M, Ruiz-Ortega JA, Ugedo L, Pineda J. Excitatory regulation of noradrenergic neurons by l-arginine/nitric oxide pathway in the rat locus coeruleus in vivo. Naunyn Schmiedebergs Arch Pharmacol 2007; 375:337-47. [PMID: 17473915 DOI: 10.1007/s00210-007-0163-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 04/04/2007] [Indexed: 11/28/2022]
Abstract
To elucidate conflicting findings about the role of L-arginine/nitric oxide (NO) pathway in the locus coeruleus (LC), we investigated the effects of different drugs affecting NO concentrations by single-unit extracellular recordings from LC neurons in vivo and in vitro. In anesthetized rats, central (3.8-15.3 nmol i.c.v.) and local (16.5-66 pmol into the LC) administrations of the NO donor sodium nitroprusside, but not those of the inactive analogue potassium ferricyanide (16.5-66 pmol into the LC), increased by 65-84% the firing rate of LC neurons. In brain slices, low concentrations (50-200 microM) of diethylamine/NO complex, a short-lived NO releaser, also increased the neuron firing rate, although higher drug concentrations (400-800 microM) caused slowly reversible reductions of the firing activity. On the other hand, the NO synthase inhibitors N(omega)-nitro-L-arginine methyl ester (L-NAME) (148-371 nmol i.c.v.) and N(omega)-nitro-L-arginine (L-NA) (46 nmol i.c.v.) gradually decreased the firing rate of LC neurons, whereas the NO synthase substrate L-arginine (0.71-1.42 micromol i.c.v. and 0.6-4.8 nmol into the LC) increased the neuron activity. The latter effect was not mimicked by the vehicle or the less active isomer D-arginine (0.6-4.8 nmol into the LC). Unexpectedly, pretreatment with high concentrations of L-NAME (371 nmol and 18.5 micromol i.c.v.) or L-NA (45.6 nmol i.c.v. and 0.24 nmol into the LC) failed to block the effect of L-arginine. The glutamate receptor antagonist kynurenic acid (1 micromol i.c.v.) strongly reduced the effect of L-arginine but not that of sodium nitroprusside. These data confirm in vivo a direct excitatory effect of NO on LC neurons and suggest a tonic regulation of noradrenergic neurons by NO in vivo. L-arginine also excites LC neurons, but this effect may be caused by a nitric-oxide-unrelated glutamate-receptor-mediated mechanism.
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Affiliation(s)
- María Torrecilla
- Department of Pharmacology, Faculty of Medicine, University of the Basque Country (UPV/EHU), Sarriena Auzoa z/g, E-48940, Leioa, Bizkaia, Spain
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Hausberg M, Grassi G. Mechanisms of sympathetic overactivity in patients with chronic renal failure: a role for chemoreflex activation? J Hypertens 2007; 25:47-9. [PMID: 17143171 DOI: 10.1097/hjh.0b013e3280119286] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Campese VM, Mitra N, Sandee D. Hypertension in renal parenchymal disease: why is it so resistant to treatment? Kidney Int 2006; 69:967-73. [PMID: 16528245 DOI: 10.1038/sj.ki.5000177] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The association between hypertension and chronic renal disease is well known. The pathogenesis of hypertension in patients with chronic kidney disease (CKD) is complex and multifactorial, which may explain why it is resistant to treatment. The traditional paradigm is that hypertension in CKD is due either to an excess of intravascular volume (volume dependent) or to excessive activation of the renin-angiotensin system in relation to the state of sodium/volume balance (renin-dependent hypertension). This review focuses on the importance of less established mechanisms, such as increased activity of the sympathetic nervous system, increased endothelin production, decreased availability of endothelium-derived vasodilators and structural changes of the arteries, renal ischemia, and sleep apnea.
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Affiliation(s)
- V M Campese
- Department of Medicine, Division of Nephrology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
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Ye S, Zhong H, Yanamadala S, Campese VM. Oxidative stress mediates the stimulation of sympathetic nerve activity in the phenol renal injury model of hypertension. Hypertension 2006; 48:309-15. [PMID: 16785328 DOI: 10.1161/01.hyp.0000231307.69761.2e] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Renal injury caused by the injection of phenol in the lower pole of one kidney increases blood pressure (BP), norepinephrine secretion from the posterior hypothalamic nuclei (PH), and renal sympathetic nerve activity in the rat. Renal denervation prevents these effects of phenol. We have also demonstrated that noradrenergic traffic in the brain is modulated by NO and interleukin-1beta. In this study, we tested the hypothesis that the increase in sympathetic nervous system (SNS) activity in the phenol renal injury model is because of activation of reactive oxygen species. To this end, first we examined the abundance of several components of reduced nicotinamide-adenine dinucleotide phosphate oxidase (identified as the major source of reactive oxygen species), including gp91phox/Nox2, p22phox, p47phox, and Nox3 using real-time PCR. Second, we evaluated the effects of 2 superoxide dismutase mimetic, tempol (4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl), and superoxide dismutase-polyethylene glycol on central and peripheral SNS activation caused by intrarenal phenol injection. Intrarenal injection of phenol raised BP, NE secretion from the PH, renal sympathetic nerve activity, and the abundance of reduced nicotinamide-adenine dinucleotide phosphate and reduced the abundance of interleukin-1beta and neural-NO synthase mRNA in the PH, paraventricular nuclei, and locus coeruleus compared with control rats. When tempol or superoxide dismutase-polyethylene glycol were infused in the lateral ventricle before phenol, the effects of phenol on BP and SNS activity were abolished. The studies suggest that central activation of the SNS in the phenol-renal injury model is mediated by increased reactive oxygen species in brain nuclei involved in the noradrenergic control of BP.
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Affiliation(s)
- Shaohua Ye
- Division of Nephrology, Hypertension Center, Keck School of Medicine, University of Southern California, 1200 North State St, Los Angeles, CA 90033, USA
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Campese VM, Shaohua Y, Huiquin Z. Oxidative stress mediates angiotensin II-dependent stimulation of sympathetic nerve activity. Hypertension 2005; 46:533-9. [PMID: 16116043 DOI: 10.1161/01.hyp.0000179088.57586.26] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Evidence indicates that angiotensin II (Ang II) enhances sympathetic nervous system (SNS) activity centrally and peripherally, but the exact mechanisms of this activation are not well established. We have previously shown that infusion of Ang II in the lateral cerebral ventricle raises blood pressure (BP), renal sympathetic nervous system activity (RSNA), and norepinephrine (NE) secretion from the posterior hypothalamic nuclei (PH), and reduces the abundance of interleukin-1beta (IL-1beta) and neuronal NO synthase (nNOS) mRNA in the PH. Pretreatment with an Ang II type 1 (AT1) receptor antagonist abolished these effects of Ang II. The data support the hypothesis that Ang II stimulates SNS through activation of AT1 receptors and downregulation of nNOS. In the current studies, we tested the hypothesis that the effects of Ang II on central SNS are mediated by reactive oxygen species. To this end, we evaluated the effects of Ang II alone or in combination with 2 superoxide dismutase (SOD) mimetics, tempol (4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl) and polyethylene glycol-SOD (PEG-SOD) on BP, NE secretion from the PH, RSNA, and abundance of IL-1beta and nNOS mRNA in the PH Ang II raised BP, NE secretion from the PH, and RSNA and reduced the abundance of IL-1beta and nNOS mRNA in the PH. Tempol and PEG-SOD completely abolished these actions of Ang II. In conclusion, these studies support the hypothesis that the effects of centrally administered Ang II on the SNS are mediated by increased oxidative stress in brain regions involved in the noradrenergic control of BP.
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Affiliation(s)
- Vito M Campese
- Division of Nephrology, Hypertension Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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Abstract
Hypertension affects 24% of the adult US population. In the United States, 3% of the adult population has an elevated serum creatinine level, and 70% of these patients have hypertension. The prevalence of hypertension in chronic kidney disease (CKD) depends on the patient's age and the severity of renal failure, proteinuria, and underlying renal disease. As patients with CKD progress to end-stage renal disease (ESRD), 86% are diagnosed with hypertension. It has long been recognized that kidney function affects and is affected by hypertension. This article discusses the pathophysiology and management of hypertension in patients with CKD.
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Affiliation(s)
- Rajiv Agarwal
- Division of Nephrology, Department of Medicine, Emerson Hall Room 520, Indiana University School of Medicine, and Roudebush VA Medical Center, 1481 West 10th Street 111 N, Indianapolis, IN 46202, USA.
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Abstract
The kidneys are vital in the pathogenesis of hypertension and are also pathologically affected by the presence of hypertension. The prevalence of hypertension in chronic kidney disease (CKD) depends on age, the severity of renal failure, and proteinuria. The intricate and inextricable relationship between CKD and hypertension seems to cause cardiovascular disease that has assumed epidemic proportions. This article discusses the etiology and treatment of hypertension in CKD so that it can be better controlled.
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Affiliation(s)
- Martin J Andersen
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine and Richard L. Roudebush Veterans Affairs Medical Center, 1481 West 10th Street, 111N, Indianapolis, IN 46202, USA
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Tandai-Hiruma M, Horiuchi J, Sakamoto H, Kemuriyama T, Hirakawa H, Nishida Y. Brain neuronal nitric oxide synthase neuron-mediated sympathoinhibition is enhanced in hypertensive Dahl rats. J Hypertens 2005; 23:825-34. [PMID: 15775788 DOI: 10.1097/01.hjh.0000163152.27954.7a] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To elucidate the role of central neurons containing neuronal nitric oxide synthase (nNOS neurons) in the sympathetic nervous system in hypertensive Dahl salt-sensitive (DS) rats. DESIGN AND METHODS Dahl rats were fed either a regular-salt (0.4% NaCl) or high-salt (8% NaCl) diet for 4 weeks. The effect of intracerebroventricular administration of S-methyl-L-thiocitrulline, a selective nNOS inhibitor, on renal sympathetic nerve activity was examined in chronically instrumented conscious DS rats. The activity and protein amount of brain nNOS was evaluated by enzyme assay and western blot analysis. The distribution and number of nNOS neurons in the brainstem were examined immunohistochemically in hypertensive and normotensive DS rats. RESULTS S-methyl-L-thiocitrulline induced a larger increase in tonic renal sympathetic nerve activity generated before baroreflex-mediated inhibition in hypertensive DS rats than normotensive DS rats. Hypertensive DS rats showed increased nNOS activity in the brainstem, but not in the diencephalon or cerebellum. High nNOS activity was confirmed by an increase in the amount of nNOS protein. nNOS Neurons were localized in several nuclei throughout the brainstem; the dorsolateral periaqueductal gray, pedunculopontine tegmental nucleus, dorsal raphe nucleus, laterodorsal tegmental nucleus, lateral parabrachial nucleus, rostral ventrolateral medulla, nucleus tractus solitarius and raphe magnus. The number of nNOS neurons in these nuclei, except for the two raphes, was significantly greater in hypertensive than in normotensive DS rats. CONCLUSIONS These findings suggest that central nNOS-mediated sympathoinhibition may be enhanced in salt-sensitive hypertensive Dahl rats. The upregulated nNOS-mediated inhibition may occur in the central sympathetic control system generated before baroreflex-mediated inhibition.
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Affiliation(s)
- Megumi Tandai-Hiruma
- Department of Physiology II, National Defense Medical College, Tokorozawa, Saitama, Japan.
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Neumann J, Ligtenberg G, Klein II, Koomans HA, Blankestijn PJ. Sympathetic hyperactivity in chronic kidney disease: pathogenesis, clinical relevance, and treatment. Kidney Int 2004; 65:1568-76. [PMID: 15086894 DOI: 10.1111/j.1523-1755.2004.00552.x] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiovascular morbidity and mortality importantly influence live expectancy of patients with chronic renal disease (CKD). Traditional risk factors are usually present, but several other factors have recently been identified. There is now evidence that CKD is often characterized by an activated sympathetic nervous system. This may contribute to the pathogenesis of renal hypertension, but it may also adversely affect prognosis independently of its effect on blood pressure. The purpose of this review is to summarize available knowledge on the role of the sympathetic nervous system in the pathogenesis of renal hypertension, its clinical relevance, and the consequences of this knowledge for the choice of treatment.
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Affiliation(s)
- Jutta Neumann
- Department of Nephrology, University Medical Center Utrecht, The Netherlands
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Kolo LL, Westfall TC, Macarthur H. Modulation of neurotransmitter release by NO is altered in mesenteric arterial bed of spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2004; 287:H1842-7. [PMID: 15205164 DOI: 10.1152/ajpheart.00013.2004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) reacts with catecholamines resulting in their deactivation. In the present study with the use of the perfused mesenteric arterial bed as a model of the sympathetic neuroeffector junction, the NO synthase (NOS) inhibitor Nω-nitro-l-arginine methyl ester (l-NAME) resulted in the enhancement of the periarterial nerve stimulation-induced increase in perfusion pressure and norepinephrine overflow while decreasing neuropeptide Y (NPY) overflow. These changes were prevented by l-arginine, demonstrating that the effects of l-NAME were specific to the inhibition of NOS. From the fact that norepinephrine acts on prejunctional α2-adrenoceptors to inhibit the evoked release of sympathetic cotransmitters, we carried out experiments in the presence of the α2-adrenergic receptor antagonist yohimbine to investigate the possibility that the decrease in NPY observed in the presence of l-NAME was due to the increase in bioactive norepinephrine acting on its autoreceptor. Periarterial nerve stimulation in the presence of both l-NAME and yohimbine prevented the previously observed decrease in NPY, indicating that the cause of this decrease was, as predicted, due to α2-adrenoceptor activation. The periarterial nerve stimulation-induced increase of norepinephrine overflow was greater in the spontaneously hypertensive rat compared with normotensive rats. In contrast to what was observed in the isolated perfused mesenteric arterial bed obtained from normotensive animals, inhibition of NOS did not result in a further increase in the overflow of norepinephine or in a subsequent decrease in NPY. These results demonstrate that, in addition to being a direct vasodilator, NO, by deactivating norepinephrine, can modulate sympathetic neurotransmission and that this modulation is altered in the spontaneously hypertensive rat.
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Affiliation(s)
- Lacy L Kolo
- Department of Pharmacological and Physiological Science, Saint Louis University, 1402 South Grand Blvd., St. Louis, MO 63104, USA
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Campese VM, Ye S, Zhong H, Yanamadala V, Ye Z, Chiu J. Reactive oxygen species stimulate central and peripheral sympathetic nervous system activity. Am J Physiol Heart Circ Physiol 2004; 287:H695-703. [PMID: 15277201 DOI: 10.1152/ajpheart.00619.2003] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent studies have implicated reactive oxygen species (ROS) in the pathogenesis of hypertension and activation of the sympathetic nervous system (SNS). Because nitric oxide (NO) exerts a tonic inhibition of central SNS activity, increased production of ROS could enhance inactivation of NO and result in activation of the SNS. To test the hypothesis that ROS may modulate SNS activity, we infused Tempol (4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl), a superoxide dismutase mimetic, or vehicle either intravenously (250 microg x kg(-1) x min(-1)) or in the lateral ventricle (50 microg x kg body wt(-1) x min(-1)), and we determined the effects on blood pressure (BP), norepinephrine (NE) secretion from the posterior hypothalamus (PH) measured by the microdialysis technique, renal sympathetic nerve activity (RSNA) measured by direct microneurography, the abundance of neuronal NO synthase (nNOS)-mRNA in the PH, paraventricular nuclei (PVN), and locus coeruleus (LC) measured by RT-PCR, and the secretion of nitrate/nitrite (NO(x)) in the dialysate collected from the PH of Sprague-Dawley rats. Tempol reduced BP whether infused intravenously or intracerebroventricularly. Tempol reduced NE secretion from the PH and RSNA when infused intracerebroventricularly but raised NE secretion from the PH and RSNA when infused intravenously. The effects of intravenous Tempol on SNS activity were blunted or abolished by sinoaortic denervation. Tempol increased the abundance of nNOS in the PH, PVN, and LC when infused intracerebroventricularly, but it decreased the abundance of nNOS when infused intravenously. When given intracerebroventricularly, Tempol also reduced the concentration of NO(x) in the dialysate collected from the PH. Pretreatment with N(omega)-nitro-l-arginine methyl ester did not abolish the effects of intracerebral Tempol on BP, heart rate, NE secretion from the PH, and RSNA suggesting that the effects of Tempol on SNS activity may be in part dependent and in part independent of NO. In all, these studies support the notion that ROS may raise BP via activation of the SNS. This activation may be mediated in part by downregulation of nNOS and NO production, in part by mechanisms independent of NO. The discrepancy in results between intracerebroventricular and intravenous infusion of Tempol can be best explained by direct inhibitory actions on SNS activity when given intracerebral. By contrast, Tempol may exert direct vasodilation of the peripheral circulation and reflex activation of the SNS when given intravenously.
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Affiliation(s)
- Vito M Campese
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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Abstract
Much evidence indicates increased sympathetic nervous activity (SNA) in renal disease. Renal ischemia is probably a primary event leading to increased SNA. Increased SNA often occurs in association with hypertension. However, the deleterious effect of increased SNA on the diseased kidney is not only caused by hypertension. Another characteristic of renal disease is unbalanced nitric oxide (NO) and angiotensin (Ang) activity. Increased SNA in renal disease may be sustained because a state of NO-Ang II unbalance is also present in the hypothalamus. Very few studies have directly compared the efficacy of adrenergic blockade with other renoprotective measures. Third-generation beta-blockers seem to have more protective effects than traditional beta-blockers, possibly via stimulation of NO release. Although it has been extensively documented that muscle SNA is increased in chronic renal failure, data on renal SNA and cardiac SNA are not available for these patients before end-stage renal disease. It is also unknown whether additional treatment with third-generation beta-blockers can delay the progression of renal injury and prevent cardiac injury in chronic renal failure more efficiently than conventional treatment with angiotensin-converting enzyme inhibitors only.
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Affiliation(s)
- Jaap A Joles
- Department of Nephrology and Hypertension (Room F03.226), University Medical Center, Heidelberglaan 100, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
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Salas N, Terrell MLA, Summy-Long JY, Kadekaro M. Role of prostaglandin, endothelin and sympathetic nervous system on the L-NAME-induced pressor responses in spontaneously hypertensive rats. Brain Res 2003; 983:162-73. [PMID: 12914977 DOI: 10.1016/s0006-8993(03)03052-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We tested the hypothesis that in spontaneously hypertensive rat (SHR) NO produced centrally influences the resting arterial blood pressure by attenuating mechanisms involving prostaglandins, angiotensin II, endothelin and sympathetic nervous system. L-NAME (200 micro g/5 micro l), an inhibitor of NO synthase, administered intracerebroventricularly (i.c.v.) to awake and freely moving rats increased mean arterial blood pressure (MABP) in a biphasic pattern: an early transient increase within 1 min and a late prolonged response starting at 45 min and persisting for the duration of experiment (180 min). The two pressor responses involve different neurochemical mechanisms and, based on their latencies, they appear to reflect different anatomical sites of action of L-NAME. The late, but not the early pressor response, was prevented by pretreatment with chlorisondamine (2.5 mg/kg, i.v.), a ganglionic blocker, indicating its dependence on the sympathetic nervous system. Both pressor responses were abolished by i.c.v. pretreatment with indomethacin (200 micro g/5 micro l, i.c.v.), an inhibitor of cyclo-oxygenase, showing that they are mediated by prostaglandin(s). In contrast, losartan (25 micro g/5 micro l), an angiotensin II AT(1) receptor antagonist, had no effect. The initial pressor response was also attenuated by pretreatment with the endothelin ET(A)/ET(B) receptor antagonist, PD 145065 (48 micro g/2 micro l, i.c.v.). Intravenous pretreatment with another ET(A)/ET(B) receptor antagonist, L-754,142 (15 mg/kg as a bolus+15 mg/kg/h for 180 min), however, attenuated both responses to L-NAME. It is possible that L-754,142 crossed the blood-brain barrier and blocked, in addition, central ET(A)/ET(B) receptors. These studies show that NO synthesized in the brain attenuates pressor mechanisms involving prostaglandin, endothelin and sympathetic nervous system, but not angiotensin II, to modulate resting arterial blood pressure.
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Affiliation(s)
- Nilson Salas
- Division of Neurosurgery, The University of Texas Medical Branch at Galveston, 301 University Boulevard, Galveston, TX 77555-0517, USA
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Wibo M. Brain nitric oxide synthase in hypertension. J Hypertens 2003; 21:1623-4. [PMID: 12923390 DOI: 10.1097/00004872-200309000-00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Qadri F, Arens T, Schwarz EC, Häuser W, Dendorfer A, Dominiak P. Brain nitric oxide synthase activity in spontaneously hypertensive rats during the development of hypertension. J Hypertens 2003; 21:1687-94. [PMID: 12923401 DOI: 10.1097/00004872-200309000-00018] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Blockade of neuronal nitric oxide synthase (nNOS) in the brain induced an increase in mean arterial pressure of spontaneously hypertensive rats (SHR). We hypothesize that increased nitric oxide (NO) synthesis in the brain compensates for hypertension. Therefore, we measured NOS activity in different brain regions in SHR at prehypertensive, onset and established hypertension, and compared with age-matched Wistar-Kyoto (WKY) rats. METHOD NOS activity was measured by the ability of tissue homogenate to convert [3H]l-arginine to [3H]l-citrulline in a Ca2+- and NADPH-dependent manner. RESULTS NOS activity was impaired in the cerebral cortex and brainstem of prehypertensive SHR. At established hypertension, SHR showed an augmentation in NOS activity in hypothalamus and brainstem. Chronic treatment of SHR with the angiotensin-1 converting enzyme (ACE)-inhibitor, enalapril, and the AT(1) receptor antagonist, losartan, normalized NOS activity in the hypothalamus but not in the brainstem. Treatment with a peripheral vasodilator, hydralazine, did not affect NOS activity. CONCLUSION Attenuated NOS activity in the cortex and brainstem of prehypertensive SHR may play a role in the pathogenesis of hypertension. The upregulated NOS activity in the hypothalamus and brainstem of SHR possibly serves to compensate for hypertension. Hypothalamic, but not brainstem, NO is involved in antihypertensive effects of ACE inhibition and AT(1) receptor blockade. Since a blood pressure decrease per se had no effect on NOS activity, it appears that central sympathetic activity influenced by endogenous angiotensin II, rather than blood pressure, represents the stimulus for the increased NOS activity in the hypothalamus of SHR.
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Affiliation(s)
- Fatimunnisa Qadri
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany.
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Ni Z, Vaziri ND. Downregulation of nitric oxide synthase in nephrotic syndrome: role of proteinuria. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1638:129-37. [PMID: 12853118 DOI: 10.1016/s0925-4439(03)00061-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Blood pressure is frequently elevated, blood volume is usually normal or increased and plasma renin and aldosterone are usually low in nephrotic syndrome (NS). These observations challenge the conventional view attributing sodium retention in NS to a hypoalbuminemia-induced intravascular volume contraction. Given the pivotal role of nitric oxide (NO) in regulation of renal sodium (Na) handling, vascular resistance and sympathetic activity, we considered that Na retention and hypertension in NS may be associated with impaired NO system. Urinary excretion of Na and NO metabolites (NOx), as well as immunodetectable endothelial (eNOS), inducible (iNOS) and neuronal (nNOS) NO synthases were determined in rats with puromycin aminonucleoside (PAN)-induced NS, rats with protein overload proteinuria, Nagase rats (NAR) with inherited analbuminemia, iNOS inhibitor (aminoguanidine)-treated rats, prenephrotic PAN-treated and placebo-treated control rats. The NS group showed marked proteinuria, hypoalbuminemia, decreased fractional excretion of Na (FENa), reduced urinary NOx excretion, and severe reduction of iNOS and nNOS protein abundance in the kidney. Similar results were found in rats with protein overload proteinuria in which proteinuria was present without hypoalbuminemia. In contrast, despite extreme hypoalbuminemia, NAR showed normal FENa, increased urinary NOx excretion and upregulations of iNOS and nNOS protein abundance in the kidney. Administration of aminoguanidine for 3 weeks lowered FENa in normal rats to levels approximating those found in the NS group. Animals studied 2 days after PAN administration (wherein proteinuria was absent) showed no abnormality. Thus, chronic PAN-induced NS results in downregulation of kidney iNOS and nNOS, which can contribute to the reduction of FENa by augmenting renal tubular Na reabsorption, and preglomerular vasoconstriction. Findings in the NAR, which had profound hypoalbuminemia without proteinuria, and in rats with protein overload proteinuria, which had proteinuria without hypoalbuminemia, point to proteinuria as the primary mediator of kidney iNOS and nNOS deficiency and impaired Na excretion in PAN-induced NS.
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Affiliation(s)
- Zhenmin Ni
- Division of Nephrology and Hypertension, Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92868, USA
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Ma SX, Ji A, Pandjaitan M, Ojije G. Enhanced nitric oxide release/synthesis in the posterior hypothalamus during nitroglycerin tolerance in rats. Eur J Pharmacol 2003; 472:179-87. [PMID: 12871752 DOI: 10.1016/s0014-2999(03)01937-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have recently observed that increasing central noradrenergic transmission and sympathomimetic activity is involved with the complex hemodynamic effects during tolerance to nitroglycerin. The present study was to examine the release of nitric oxide (NO) in the posterior hypothalamus during tolerance to depressor responses to nitroglycerin and determine if, during the tolerance, endogenous NO synthesis is induced in the posterior hypothalamus. A microdialysis probe was implanted in the posterior hypothalamus and perfusion fluid was pumped through the probe at 2 microl/min in conscious rats. Tolerance to nitroglycerin was produced by three intravenous (i.v.) injections of 1.3 mg nitroglycerin each within 40 min compared to the same administrations of low dose of the drug, sodium nitroprusside and papaverine. Dialysate samples were collected 1 h before and 1 h each after injections for 8 h. Concentrations of nitrite (NO(2)(-)), nitrate (NO(3)(-)), and total nitrite plus nitrate (NO(x)(-)) were quantified in the samples by using chemiluminescence. The dose-response curve for arterial depressor induced by intravenous injection of the challenge doses of nitroglycerin was markedly shifted to the right at the first hour after nitroglycerin tolerance, lasted 3 to 5 h and reversed at 7 h. The dialysate NO(3)(-) and NO(x)(-) concentrations in the posterior hypothalamus were significantly increased at the first hour following nitroglycerin tolerance but were not altered by low dose of the drug, sodium nitroprusside, and papaverine. Nitroglycerin tolerance predominantly caused an increase in NO(3)(-) release in the posterior hypothalamus with no or small amount of changes in dialysate NO(2)(-) and the response was partially inhibited by pretreatment with N(G)-Propyl-L-arginine (NPLA) (1.0 mg/kg, i.p.), an inhibitor of neuronal NO synthesis. The increase of NO release in the posterior hypothalamus occurred at the first hour, lasted 2 to 3 h and reversed at 5 to 6 h during nitroglycerin tolerance. The results show that systemically administered high dose of nitroglycerin increases NO release in the posterior hypothalamus which matches the time interval of tolerance to arterial depressor response to the drug. Data suggest that there is an enhanced endogenous NO synthesis in the posterior hypothalamus which may affect central sympathetic functions during nitroglycerin tolerance.
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Affiliation(s)
- Sheng-Xing Ma
- Department of Obstetrics and Gynecology, Harbor-University of California Los Angeles Medical Center, David Geffen School of Medicine at University of California at Los Angeles, 1124 W. Carson Street, RB-1, Torrance, CA 90502, USA.
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Kanellis J, Nakagawa T, Herrera-Acosta J, Schreiner GF, Rodríguez-Iturbe B, Johnson RJ. A single pathway for the development of essential hypertension. Cardiol Rev 2003; 11:180-96. [PMID: 12852795 DOI: 10.1097/01.crd.0000077361.00668.14] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- John Kanellis
- Division Of Nephrology, Baylor College Of Medicine, Houston, Texas 77030, USA
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Hirooka Y, Sakai K, Kishi T, Ito K, Shimokawa H, Takeshita A. Enhanced depressor response to endothelial nitric oxide synthase gene transfer into the nucleus tractus solitarii of spontaneously hypertensive rats. Hypertens Res 2003; 26:325-31. [PMID: 12733701 DOI: 10.1291/hypres.26.325] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Previously, we demonstrated that endothelial nitric oxide synthase (eNOS) gene transfer into the nucleus tractus solitarii (NTS) decreased blood pressure, heart rate and sympathetic nerve activity in conscious normotensive Wistar-Kyoto rats (WKY). In order to determine whether overexpression of eNOS in the NTS causes different effects on blood pressure and heart rate between spontaneously hypertensive rats (SHR) and WKY, we transfected adenovirus vectors encoding either eNOS (AdeNOS) or beta-galactosidase (Ad beta gal) into the NTS of SHR and WKY in vivo. The local expression of eNOS in the NTS was confirmed by Western blot analysis for eNOS protein, and the magnitude of expression did not differ between SHR and WKY. Blood pressure and heart rate were monitored by the use of a radio-telemetry system in a conscious state before and 7 days after the gene transfer. Systolic blood pressure (SBP) and heart rate decreased on day 7 in both AdeNOS-transfected SHR and WKY. However, the magnitude of decreases in SBP of AdeNOS-transfected SHR was greater than that of AdeNOS-transfected WKY (-24.1 +/- 2.9 vs. -15.9 +/- 2.1 mmHg, p < 0.05). Transfection of Ad beta gal into the NTS did not alter SBP in either group. A depressor response evoked by microinjection of L-glutamate into the NTS did not differ between the two strains. These results suggest that overexpression of eNOS in the NTS causes a greater depressor response in SHR than in WKY in a conscious state. An abnormality of the L-arginine-NO pathway in the NTS may be related to the hypertensive mechanism(s) of SHR.
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Affiliation(s)
- Yoshitaka Hirooka
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
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