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Kanbay M, Ertuglu LA, Afsar B, Ozdogan E, Siriopol D, Covic A, Basile C, Ortiz A. An update review of intradialytic hypotension: concept, risk factors, clinical implications and management. Clin Kidney J 2020; 13:981-993. [PMID: 33391741 PMCID: PMC7769545 DOI: 10.1093/ckj/sfaa078] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 04/30/2020] [Indexed: 12/13/2022] Open
Abstract
Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.
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Affiliation(s)
- Mehmet Kanbay
- Department of Medicine, Division of Nephrology, Koc University School of Medicine, Istanbul, Turkey
| | - Lale A Ertuglu
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Baris Afsar
- Department of Internal Medicine, Division of Nephrology, Suleyman Demirel University School of Medicine, Isparta, Turkey
| | - Elif Ozdogan
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Dimitrie Siriopol
- Nephrology Clinic, Dialysis and Renal Transplant Center, 'C.I. PARHON' University Hospital, 'Grigore T. Popa' University of Medicine, Iasi, Romania
| | - Adrian Covic
- Nephrology Clinic, Dialysis and Renal Transplant Center, 'C.I. PARHON' University Hospital, 'Grigore T. Popa' University of Medicine, Iasi, Romania
| | - Carlo Basile
- Division of Nephrology, Miulli General Hospital, Acquaviva delle Fonti, Italy.,Associazione Nefrologica Gabriella Sebastio, Martina Franca, Italy
| | - Alberto Ortiz
- Dialysis Unit, School of Medicine, IIS-Fundacion Jimenez Diaz, Universidad Autónoma de Madrid, Madrid, Spain
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Jackson KL, Head GA, Gueguen C, Stevenson ER, Lim K, Marques FZ. Mechanisms Responsible for Genetic Hypertension in Schlager BPH/2 Mice. Front Physiol 2019; 10:1311. [PMID: 31681017 PMCID: PMC6813185 DOI: 10.3389/fphys.2019.01311] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/30/2019] [Indexed: 01/18/2023] Open
Abstract
It has been 45 years since Gunther Schlager used a cross breeding program in mice to develop inbred strains with high, normal, and low blood pressure (BPH/2, BPN/3, and BPL/1 respectively). Thus, it is timely to gather together the studies that have characterized and explored the mechanisms associated with the hypertension to take stock of exactly what is known and what remains to be determined. Growing evidence supports the notion that the mechanism of hypertension in BPH/2 mice is predominantly neurogenic with some of the early studies showing aberrant brain noradrenaline levels in BPH/2 compared with BPN/3. Analysis of the adrenal gland using microarray suggested an association with the activity of the sympathetic nervous system. Indeed, in support of this, there is a larger depressor response to ganglion blockade, which reduced blood pressure in BPH/2 mice to the same level as BPN/3 mice. Greater renal tyrosine hydroxylase staining and greater renal noradrenaline levels in BPH/2 mice suggest sympathetic hyperinnervation of the kidney. Renal denervation markedly reduced the blood pressure in BPH/2 but not BPN/3 mice, confirming the importance of renal sympathetic nervous activity contributing to the hypertension. Further, there is an important contribution to the hypertension from miR-181a and renal renin in this strain. BPH/2 mice also display greater neuronal activity of amygdalo-hypothalamic cardiovascular regulatory regions. Lesions of the medial nucleus of the amygdala reduced the hypertension in BPH/2 mice and abolished the strain difference in the effect of ganglion blockade, suggesting a sympathetic mechanism. Further studies suggest that aberrant GABAergic inhibition may play a role since BPH/2 mice have low GABAA receptor δ, α4 and β2 subunit mRNA expression in the hypothalamus, which are predominantly involved in promoting tonic neuronal inhibition. Allopregnanolone, an allosteric modulator of GABAA receptors, which increase the expression of these subunits in the amygdala and hypothalamus, is shown to reduce the hypertension and sympathetic nervous system contribution in BPH/2 mice. Thus far, evidence suggests that BPH/2 mice have aberrant GABAergic inhibition, which drives neuronal overactivity within amygdalo-hypothalamic brain regions. This overactivity is responsible for the greater sympathetic contribution to the hypertension in BPH/2 mice, thus making this an ideal model of neurogenic hypertension.
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Affiliation(s)
- Kristy L Jackson
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Cindy Gueguen
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Emily R Stevenson
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Kyungjoon Lim
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| | - Francine Z Marques
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Hypertension Research Laboratory, School of Biological Sciences, Monash University, Clayton, VIC, Australia
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Jackson KL, Marques FZ, Lim K, Davern PJ, Head GA. Circadian Differences in the Contribution of the Brain Renin-Angiotensin System in Genetically Hypertensive Mice. Front Physiol 2018; 9:231. [PMID: 29615926 PMCID: PMC5868475 DOI: 10.3389/fphys.2018.00231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/01/2018] [Indexed: 11/21/2022] Open
Abstract
Objective: Genetically hypertensive BPH/2J mice are recognized as a neurogenic model of hypertension, primarily based on sympathetic overactivity and greater neuronal activity in cardiovascular regulatory brain regions. Greater activity of the central renin angiotensin system (RAS) and reactive oxygen species (ROS) reportedly contribute to other models of hypertension. Importantly the peripheral RAS contributes to the hypertension in BPH/2J mice, predominantly during the dark period of the 24 h light cycle. The aim of the present study was to determine whether central AT1 receptor stimulation and the associated ROS signaling contribute to hypertension in BPH/2J mice in a circadian dependent manner. Methods: Blood pressure (BP) was measured in BPH/2J and normotensive BPN/3J mice (n = 7–8) via pre-implanted telemetry devices. Acute intracerebroventricular (ICV) microinjections of AT1 receptor antagonist, candesartan, and the superoxide dismutase (SOD) mimetic, tempol, were administered during the dark and light period of the 24 h light cycle via a pre-implanted ICV guide cannula. In separate mice, the BP effect of ICV infusion of the AT1 receptor antagonist losartan for 7 days was compared with subcutaneous infusion to determine the contribution of the central RAS to hypertension in BPH/2J mice. Results: Candesartan administered ICV during the dark period induced depressor responses which were 40% smaller in BPH/2J than BPN/3J mice (Pstrain < 0.05), suggesting AT1 receptor stimulation may contribute less to BP maintenance in BPH/2J mice. During the light period candesartan had minimal effect on BP in either strain. ICV tempol had comparable effects on BP between strains during the light and dark period (Pstrain > 0.08), suggesting ROS signaling is also not contributing to the hypertension in BPH/2J mice. Chronic ICV administration of losartan (22 nmol/h) had minimal effect on BPN/3J mice. By contrast in BPH/2J mice, both ICV and subcutaneously administered losartan induced similar hypotensive responses (−12.1 ± 1.8 vs. −14.7 ± 1.8 mmHg, Proute = 0.31). Conclusion: While central effects of peripheral losartan cannot be excluded, we suggest the hypotensive effect of chronic ICV losartan was likely peripherally mediated. Thus, based on both acute and chronic AT1 receptor inhibition and acute ROS inhibition, our findings suggest that greater activation of central AT1 receptors or ROS are unlikely to be mediating the hypertension in BPH/2J mice.
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Affiliation(s)
- Kristy L Jackson
- Neuropharmacology Laboratory, Baker Heart and Diabetes Research Institute, Melbourne, VIC, Australia
| | - Francine Z Marques
- Department of Pharmacology, Monash University, Victoria, VIC, Australia.,Heart Failure Research Group, Baker Heart and Diabetes Research Institute, Melbourne, VIC, Australia
| | - Kyungjoon Lim
- Neuropharmacology Laboratory, Baker Heart and Diabetes Research Institute, Melbourne, VIC, Australia.,Department of Physiology, Anatomy and Microbiology, Latrobe University, Bundoora, VIC, Australia
| | - Pamela J Davern
- Neuropharmacology Laboratory, Baker Heart and Diabetes Research Institute, Melbourne, VIC, Australia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker Heart and Diabetes Research Institute, Melbourne, VIC, Australia.,Department of Pharmacology, Monash University, Victoria, VIC, Australia
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Renin-angiotensin system acting on reactive oxygen species in paraventricular nucleus induces sympathetic activation via AT1R/PKCγ/Rac1 pathway in salt-induced hypertension. Sci Rep 2017; 7:43107. [PMID: 28338001 PMCID: PMC5364504 DOI: 10.1038/srep43107] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 01/19/2017] [Indexed: 02/04/2023] Open
Abstract
Brain renin-angiotensin system (RAS) could regulate oxidative stress in the paraventricular nucleus (PVN) in the development of hypertension. This study was designed to explore the precise mechanisms of RAS acting on reactive oxygen species (ROS) in salt-induced hypertension. Male Wistar rats were administered with a high-salt diet (HS, 8.0% NaCl) for 8 weeks to induced hypertension. Those rats were received PVN infusion of AT1R antagonist losartan (LOS, 10 μg/h) or microinjection of small interfering RNAs for protein kinase C γ (PKCγ siRNA) once a day for 2 weeks. High salt intake resulted in higher levels of AT1R, PKCγ, Rac1 activity, superoxide and malondialdehyde (MDA) activity, but lower levels of copper/zinc superoxide dismutase (Cu/Zn-SOD), superoxide dismutase (SOD) and glutathione (GSH) in PVN than control animals. PVN infusion of LOS not only attenuated the PVN levels of AT1R, PKCγ, Rac1 activity, superoxide and decreased the arterial pressure, but also increased the PVN antioxidant capacity in hypertension. PVN microinjection of PKCγ siRNA had the same effect on LOS above responses to hypertension but no effect on PVN level of AT1R. These results, for the first time, identified that the precise signaling pathway of RAS regulating ROS in PVN is via AT1R/PKCγ/Rac1 in salt-induced hypertension.
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Daugirdas JT, Depner TA, Inrig J, Mehrotra R, Rocco MV, Suri RS, Weiner DE, Greer N, Ishani A, MacDonald R, Olson C, Rutks I, Slinin Y, Wilt TJ, Rocco M, Kramer H, Choi MJ, Samaniego-Picota M, Scheel PJ, Willis K, Joseph J, Brereton L. KDOQI Clinical Practice Guideline for Hemodialysis Adequacy: 2015 Update. Am J Kidney Dis 2015; 66:884-930. [DOI: 10.1053/j.ajkd.2015.07.015] [Citation(s) in RCA: 603] [Impact Index Per Article: 67.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 07/31/2015] [Indexed: 12/13/2022]
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Palkovits M, Šebeková K, Klenovics KS, Kebis A, Fazeli G, Bahner U, Heidland A. Neuronal activation in the central nervous system of rats in the initial stage of chronic kidney disease-modulatory effects of losartan and moxonidine. PLoS One 2013; 8:e66543. [PMID: 23818940 PMCID: PMC3688530 DOI: 10.1371/journal.pone.0066543] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/18/2013] [Indexed: 11/19/2022] Open
Abstract
The effect of mild chronic renal failure (CRF) induced by 4/6-nephrectomy (4/6NX) on central neuronal activations was investigated by c-Fos immunohistochemistry staining and compared to sham-operated rats. In the 4/6 NX rats also the effect of the angiotensin receptor blocker, losartan, and the central sympatholyticum moxonidine was studied for two months. In serial brain sections Fos-immunoreactive neurons were localized and classified semiquantitatively. In 37 brain areas/nuclei several neurons with different functional properties were strongly affected in 4/6NX. It elicited a moderate to high Fos-activity in areas responsible for the monoaminergic innervation of the cerebral cortex, the limbic system, the thalamus and hypothalamus (e.g. noradrenergic neurons of the locus coeruleus, serotonergic neurons in dorsal raphe, histaminergic neurons in the tuberomamillary nucleus). Other monoaminergic cell groups (A5 noradrenaline, C1 adrenaline, medullary raphe serotonin neurons) and neurons in the hypothalamic paraventricular nucleus (innervating the sympathetic preganglionic neurons and affecting the peripheral sympathetic outflow) did not show Fos-activity. Stress- and pain-sensitive cortical/subcortical areas, neurons in the limbic system, the hypothalamus and the circumventricular organs were also affected by 4/6NX. Administration of losartan and more strongly moxonidine modulated most effects and particularly inhibited Fos-activity in locus coeruleus neurons. In conclusion, 4/6NX elicits high activity in central sympathetic, stress- and pain-related brain areas as well as in the limbic system, which can be ameliorated by losartan and particularly by moxonidine. These changes indicate a high sensitivity of CNS in initial stages of CKD which could be causative in clinical disturbances.
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Affiliation(s)
- Miklós Palkovits
- Neuromorphological and Neuroendocrine Research Laboratory, Semmelweis University and the Hungarian Academy of Sciences, Budapest, Hungary
| | - Katarína Šebeková
- Institute of Molecular Biomedicine, Medical Faculty, Comenius University, Bratislava, Slovakia
| | | | - Anton Kebis
- Laboratory of Organ Perfusion of Slovak Center of Organ Transplantation, Slovak Medical University, Bratislava, Slovakia
| | - Gholamreza Fazeli
- Institute of Pharmacology and Toxicology, University of Wuerzburg, Wuerzburg, Germany
| | | | - August Heidland
- Department of Internal Medicine, University of Wuerzburg and KfH-Kidney Centre, Wuerzburg, Germany
- * E-mail:
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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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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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Santos SFF, Peixoto AJ. Revisiting the dialysate sodium prescription as a tool for better blood pressure and interdialytic weight gain management in hemodialysis patients. Clin J Am Soc Nephrol 2008; 3:522-30. [PMID: 18199846 PMCID: PMC6631087 DOI: 10.2215/cjn.03360807] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hypertension and chronic volume overload are complications often seen in hemodialysis patients. Current hemodialysis practices adopt a standard dialysate sodium prescription that is typically higher than the plasma sodium concentration of most patients. As a general rule, hemodialysis patients have stable predialysis plasma sodium concentrations, and each patient has a fixed "osmolar set point." Hypertonic dialysate sodium prescriptions, including sodium modeling, predispose to positive sodium balance and lead to higher blood pressure and increased interdialytic weight gain. Conversely, lowering or individualizing dialysate sodium reduces thirst, interdialytic weight gain, and blood pressure in non-hypotension prone dialysis patients. Optimization of the dialysate sodium prescription is an important step in achieving sodium balance and improving blood pressure control in hypertensive hemodialysis patients.
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Affiliation(s)
- Sergio F. F. Santos
- Division of Nephrology, State University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; and
| | - Aldo J. Peixoto
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut and Medical Service and Renal Section, VA Connecticut Healthcare System, West Haven, Connecticut
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Jordan J, Grassi G. Adrenergic overdrive: a 'not-so-sympathetic' risk factor in renal failure patients. J Hypertens 2007; 25:1197-9. [PMID: 17563531 DOI: 10.1097/hjh.0b013e3281a7369e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Pourdjabbar A, Parker TG, Desjardins JF, Nguyen QT, Tsoporis JN, Lapointe N, Rouleau JL. Losartan and acute myocardial infarction in insulin-resistant Zucker fatty rats: reduced ventricular arrhythmias and improved survival. Can J Physiol Pharmacol 2006; 83:989-98. [PMID: 16391707 DOI: 10.1139/y05-072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin resistance (IR) and diabetes increase the risk of acute myocardial infarction (MI). Angiotensin receptor blockers (ARBs) have been shown to reduce the risk of cardiovascular events in patients with hypertension and diabetes, and to be beneficial after a large MI. Whether pretreatment with ARBs is beneficial in acute MI is unknown. We evaluated whether pre-, peri-, and post-MI treatment with the ARB losartan improved the outcome in the IR Zucker fatty rat (ZFR). ZFR (n=264) received either losartan (3 mg/kg daily) or vehicle for 7 d prior to MI. Early (24 h) protocol (n=31): ventricular arrhythmias were evaluated post-MI using continuous ambulatory ECG monitoring. Late (38 d) protocol (n=233): losartan was increased to 10 mg/kg daily 10 d post-MI and to 30 mg/kg daily 20 d post-MI. Blood glucose, cardiac hemodynamics and remodeling, GLUT-4, fetal gene expression, and survival were evaluated. In large-MI rats, losartan improved early survival (43% vs. 27% in controls, p=0.01) and late survival (23% vs.15% in controls, p=0.02). Improved early survival was associated with a reduction in ventricular arrhythmias. Losartan reduced pulmonary congestion, cardiac hypertrophy, and fetal gene expression in the absence of statistically significant changes in ventricular dilatation and hemodynamics. Blood glucose and cardiac GLUT-4 expression did not change with losartan. In IR ZFR, losartan improves post-MI survival, likely as a result of an early reduction in ventricular arrhythmias. There was also an associated reduction in pulmonary congestion, hypertrophy, and fetal gene expression.
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Affiliation(s)
- Ali Pourdjabbar
- Division of Cardiology, St. Michael's Hospital, University Health Network, Toronto, ON, Canada
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Béchir M, Enseleit F, Chenevard R, Lüscher TF, Noll G. Effect of losartan on muscle sympathetic activity and baroreceptor function in systemic hypertension. Am J Cardiol 2005; 95:129-31. [PMID: 15619411 DOI: 10.1016/j.amjcard.2004.08.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 08/24/2004] [Accepted: 08/24/2004] [Indexed: 10/26/2022]
Abstract
Angiotensin II directly stimulates muscle sympathetic nerve activity and facilitates adrenergic sympathetic transmission. The hypotheses that the chronic blockade of angiotensin II receptors (AT(1) type) reduces muscle sympathetic activity and that there is an interaction with baroreceptor function in patients with mild to moderate hypertension were investigated. Muscle sympathetic nerve activity decreased from 51.7 +/- 3.5 to 45.9 +/- 4.2 bursts/min (p = 0.022), and cardiac baroreceptor sensitivity increased from 3.2 +/- 1.3 to 4.9 +/- 1.8 ms/mm Hg (p = 0.007). This study for the first time demonstrates that in hypertensive patients, chronic AT(1) receptor antagonism inhibits muscle sympathetic nerve activity and that baroreceptor function is improved under these conditions.
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Deng PY, Ye F, Cai WJ, Deng HW, Li YJ. Role of calcitonin gene-related peptide in the phenol-induced neurogenic hypertension in rats. ACTA ACUST UNITED AC 2004; 119:155-61. [PMID: 15120475 DOI: 10.1016/j.regpep.2004.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2003] [Revised: 01/06/2004] [Accepted: 01/15/2004] [Indexed: 02/02/2023]
Abstract
Previous investigations have demonstrated that capsaicin-sensitive sensory nerves are involved in the development of hypertension in some rat models of hypertension. To determine the role played by calcitonin gene-related peptide (CGRP; the predominant neurotransmitter in capsaicin-sensitive sensory nerves) in a rat model of neurogenic hypertension, in which hypertension was induced by injecting 50 microl of 10% phenol in the lower pole of the left kidney, systolic blood pressure (SBP) was monitored by the tail-cuff method throughout the experiment. Fifteen days after injection of phenol, mean arterial pressure (MAP), concentrations of CGRP in the plasma, the expression of CGRP mRNA in dorsal root ganglia (DRG) and CGRP content in laminae I and II of the spinal cord were measured. SBP was significantly increased 5 days after the intrarenal injection of phenol (164+/-7 mm Hg, p<0.01). At the end of experiment, blood pressure (BP) was significantly elevated in the phenol-injected rats compared with the controls (SBP: 187+/-6 vs. 122+/-4 mm Hg, p<0.01; MAP: 157.56+/-3.02 vs. 103.80+/-2.04 mm Hg, p<0.01). Treatment with capsaicin, which selectively depletes neurotransmitters from the capsaicin-sensitive nerves, failed to enhance the development of hypertensive responses to the intrarenal injection of phenol. Intravenous administration of CGRP(8-37), the specific CGRP receptor antagonist, also failed to increase the already elevated MAP. The expression of CGRP mRNA (both alpha- and beta-CGRP isoforms), the content of CGRP in laminae I and II of the dorsal horn of the spinal cord and the concentration of CGRP in the plasma was decreased in the rats treated with phenol. These results suggest that CGRP does not play a counterregulatory role in the phenol-induced hypertensive rats, and support the hypothesis that reduction of CGRP (alpha and beta isoforms) could contribute to a blood pressure elevation in this setting.
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Affiliation(s)
- Pan-Yue Deng
- Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, No. 90 Xiang-Ya Road, Changsha, Hunan 410078, China
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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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