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Mahfoud F, Townsend RR, Kandzari DE, Kario K, Schmieder RE, Tsioufis K, Pocock S, David S, Patel K, Rao A, Walton A, Bloom JE, Weber T, Suppan M, Lauder L, Cohen SA, McKenna P, Fahy M, Böhm M, Weber MA. Changes in Plasma Renin Activity After Renal Artery Sympathetic Denervation. J Am Coll Cardiol 2021; 77:2909-2919. [PMID: 33957242 DOI: 10.1016/j.jacc.2021.04.044] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/23/2021] [Accepted: 04/12/2021] [Indexed: 12/25/2022]
Abstract
BACKGROUND The renin-angiotensin-aldosterone system plays a key role in blood pressure (BP) regulation and is the target of several antihypertensive medications. Renal denervation (RDN) is thought to interrupt the sympathetic-mediated neurohormonal pathway as part of its mechanism of action to reduce BP. OBJECTIVES The purpose of this study was to evaluate plasma renin activity (PRA) and aldosterone before and after RDN and to assess whether these baseline neuroendocrine markers predict response to RDN. METHODS Analyses were conducted in patients with confirmed absence of antihypertensive medication. Aldosterone and PRA levels were compared at baseline and 3 months post-procedure for RDN and sham control groups. Patients in the SPYRAL HTN-OFF MED Pivotal trial were separated into 2 groups, those with baseline PRA ≥0.65 ng/ml/h (n = 110) versus <0.65 ng/ml/h (n = 116). Follow-up treatment differences between RDN and sham control groups were adjusted for baseline values using multivariable linear regression models. RESULTS Baseline PRA was similar between RDN and control groups (1.0 ± 1.1 ng/ml/h vs. 1.1 ± 1.1 ng/ml/h; p = 0.37). Change in PRA at 3 months from baseline was significantly greater for RDN compared with control subjects (-0.2 ± 1.0 ng/ml/h; p = 0.019 vs. 0.1 ± 0.9 ng/ml/h; p = 0.14), p = 0.001 for RDN versus control subjects, and similar differences were seen for aldosterone: RDN compared with control subjects (-1.2 ± 6.4 ng/dl; p = 0.04 vs. 0.4 ± 5.4 ng/dl; p = 0.40), p = 0.011. Treatment differences at 3 months in 24-h and office systolic blood pressure (SBP) for RDN versus control patients were significantly greater for patients with baseline PRA ≥0.65 ng/ml/h versus <0.65 ng/ml/h, despite similar baseline BP. Differences in office SBP changes according to baseline PRA were also observed earlier at 2 weeks post-RDN. CONCLUSIONS Plasma renin activity and aldosterone levels for RDN patients were significantly reduced at 3 months when compared with baseline as well as when compared with sham control. Higher baseline PRA levels were associated with a significantly greater reduction in office and 24-h SBP. (SPYRAL PIVOTAL - SPYRAL HTN-OFF MED Study; NCT02439749).
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Affiliation(s)
- Felix Mahfoud
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, Saarland University, Homburg/Saar, Germany.
| | - Raymond R Townsend
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David E Kandzari
- Department of Interventional Cardiology, Piedmont Heart Institute, Atlanta, Georgia, USA
| | - Kazuomi Kario
- Department of Cardiovascular Medicine and Department of Sleep and Circadian Cardiology, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Roland E Schmieder
- Department of Nephrology and Hypertension, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Konstantinos Tsioufis
- Department of Cardiology, University of Athens, Hippocratio Hospital, Athens, Greece
| | - Stuart Pocock
- Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Shukri David
- Department of Cardiology, Providence Hospital, Southfield, Michigan, USA
| | - Kiritkumar Patel
- Department of Cardiology, Saint Joseph Mercy Oakland, Bloomfield Hills, Michigan, USA
| | - Anjani Rao
- Department of Cardiology, Saint Joseph Mercy Oakland, Bloomfield Hills, Michigan, USA
| | - Antony Walton
- Department of Cardiology, The Alfred Hospital, Melbourne, Victoria, Australia
| | - Jason E Bloom
- Department of Cardiology, The Alfred Hospital, Melbourne, Victoria, Australia
| | - Thomas Weber
- Department of Cardiology, Klinikum Wels-Grieskirchen, Wels, Austria
| | - Markus Suppan
- Department of Cardiology, Klinikum Wels-Grieskirchen, Wels, Austria
| | - Lucas Lauder
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, Saarland University, Homburg/Saar, Germany
| | - Sidney A Cohen
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Coronary and Renal Denervation Division, Medtronic PLC, Santa Rosa, California, USA
| | - Pamela McKenna
- Coronary and Renal Denervation Division, Medtronic PLC, Santa Rosa, California, USA
| | - Martin Fahy
- Coronary and Renal Denervation Division, Medtronic PLC, Santa Rosa, California, USA
| | - Michael Böhm
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, Saarland University, Homburg/Saar, Germany
| | - Michael A Weber
- Department of Medicine, SUNY Downstate College of Medicine, Brooklyn, New York, USA
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van Loon LM, Rongen GA, van der Hoeven JG, Veltink PH, Lemson J. β-Blockade attenuates renal blood flow in experimental endotoxic shock by reducing perfusion pressure. Physiol Rep 2019; 7:e14301. [PMID: 31814327 PMCID: PMC6900489 DOI: 10.14814/phy2.14301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Clinical data suggests that heart rate (HR) control with selective β1-blockers may improve cardiac function during septic shock. However, it seems counterintuitive to start β-blocker infusion in a shock state when organ blood flow is already low or insufficient. Therefore, we studied the effects of HR control with esmolol, an ultrashort- acting β1-selective adrenoceptor antagonist, on renal blood flow (RBF) and renal autoregulation during early septic shock. In 10 healthy sheep, sepsis was induced by continuous i.v. administration of lipopolysaccharide, while maintained under anesthesia and mechanically ventilated. After successful resuscitation of the septic shock with fluids and vasoactive drugs, esmolol was infused to reduce HR with 30% and was stopped 30-min after reaching this target. Arterial and venous pressures, and RBF were recorded continuously. Renal autoregulation was evaluated by the response in RBF to renal perfusion pressure (RPP) in both the time domain and frequency domain. During septic shock, β-blockade with esmolol significantly increased the pressure dependency of RBF to RPP. Stopping esmolol showed the reversibility of the impaired renal autoregulation. Showing that clinical diligence and caution are necessary when treating septic shock with esmolol in the acute phase since esmolol reduced RPP to critical values thereby significantly reducing RBF.
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Affiliation(s)
- Lex M. van Loon
- Cardiovascular and Respiratory Physiology GroupFaculty of Science and TechnologyUniversity of TwenteEnschedeThe Netherlands
- Department of Intensive Care MedicineRadboud University Medical CenterRadboud Institute for Health SciencesNijmegenThe Netherlands
| | - Gerard A. Rongen
- Department of Pharmacology and ToxicologyRadboud University Medical CenterNijmegenThe Netherlands
| | - Johannes G. van der Hoeven
- Department of Intensive Care MedicineRadboud University Medical CenterRadboud Institute for Health SciencesNijmegenThe Netherlands
- Radboud Center for Infectious diseasesNijmegenThe Netherlands
| | - Peter H. Veltink
- Biomedical Signals and SystemsFaculty of Electrical Engineering, Mathematics and Computer ScienceTechnical Medical CentreUniversity of TwenteEnschedeThe Netherlands
| | - Joris Lemson
- Department of Intensive Care MedicineRadboud University Medical CenterRadboud Institute for Health SciencesNijmegenThe Netherlands
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McArdle Z, Pontes RB, Yao ST, Lankadeva YR, Singh RR, Hood SG, Schlaich MP, May CN, Booth LC. Blunted diuretic and natriuretic responses to acute sodium loading early after catheter-based renal denervation in normotensive sheep. Am J Physiol Regul Integr Comp Physiol 2019; 317:R319-R327. [DOI: 10.1152/ajpregu.00228.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Catheter-based renal denervation (RDN) was introduced as a treatment for resistant hypertension. There remain critical questions regarding the physiological mechanisms underlying the hypotensive effects of catheter-based RDN. Previous studies indicate that surgical denervation reduces renin and the natriuretic response to saline loading; however, the effects on these variables of catheter-based RDN, which does not yield complete denervation, are largely unknown. The aim of this study was to investigate the effects of catheter-based RDN on glomerular-associated renin and regulation of fluid and sodium homeostasis in response to physiological challenges. First, immunohistochemical staining for renin was performed in normotensive sheep ( n = 6) and sheep at 1 wk ( n = 6), 5.5 mo ( n = 5), and 11 mo ( n = 5) after unilateral RDN using the same catheter used in patients (Symplicity). Following catheter-based RDN (1 wk), renin-positive glomeruli were significantly reduced compared with sham animals ( P < 0.005). This was sustained until 5.5 mo postdenervation. To determine whether the reduction in renin after 1 wk had physiological effects, in a separate cohort, Merino ewes were administered high and low saline loads before and 1 wk after bilateral RDN ( n = 9) or sham procedure ( n = 8). After RDN (1 wk), the diuretic response to a low saline load was significantly reduced ( P < 0.05), and both the diuretic and natriuretic responses to a high saline load were significantly attenuated ( P < 0.05). In conclusion, these findings indicate that catheter-based RDN acutely alters the ability of the kidney to regulate fluid and electrolyte balance. Further studies are required to determine the long-term effects of catheter-based RDN on renal sodium and water homeostasis.
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Affiliation(s)
- Zoe McArdle
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- Cardiovascular Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Roberto B. Pontes
- Cardiovascular Division, Department of Physiology, Federal University of São Paulo, São Paulo, Brazil
| | - Song T. Yao
- Faculty of Medicine, Dentistry and Health Sciences, Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Yugeesh R. Lankadeva
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Reetu R. Singh
- Cardiovascular Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Sally G. Hood
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Markus P. Schlaich
- Dobney Hypertension Centre, School of Medicine-Royal Perth Hospital Unit, University of Western Australia, Perth, Australia
| | - Clive N. May
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Lindsea C. Booth
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
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Skrzypecki J, Ufnal M. Drug resistant hypertension – no simple way out. Kidney Blood Press Res 2016; 40:66-76. [PMID: 25791632 DOI: 10.1159/000368483] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 11/19/2022] Open
Abstract
Hypertension poses growing challenge for health policy-makers and doctors worldwide. Recently published results of Symplicity-III trial (HTN-3), the first blinded, randomized, multicenter study on the efficacy of renal denervation for the treatment of resistant hypertension did not show a significant reduction of BP in patients with resistant hypertension 6 months after renal-artery denervation, as compared with controls. In this paper we review clinical and experimental studies on renal denervation. In order to identify causes of inconsistent results in renal denervation studies we look at basic science support for renal denervation and at designs of clinical trials.
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Effects of renal denervation on regional hemodynamics and kidney function in experimental hyperdynamic sepsis. Crit Care Med 2014; 42:e401-9. [PMID: 24670939 DOI: 10.1097/ccm.0000000000000302] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To determine the influence of the renal sympathetic nerves on the pathogenesis of septic acute kidney injury. DESIGN Interventional control study to determine the effects of renal denervation in ovine hyperdynamic sepsis. SETTING Research Institute. SUBJECTS Twenty-four adult Merino ewes. INTERVENTIONS The effects of infusion of angiotensin II and norepinephrine and induction of hyperdynamic sepsis by administration of live Escherichia coli were examined in control sheep and in sheep at 2 weeks after bilateral renal denervation (n = 10/group). MEASUREMENTS AND MAIN RESULTS Systemic hemodynamics and renal function were measured in conscious sheep instrumented with flow probes on the pulmonary and renal arteries. Angiotensin II, but not norepinephrine, had a greater pressor effect in denervated animals. Sepsis increased cardiac output by 60%, renal blood flow by 35%, and arterial lactate by approximately four-fold. The denervated compared with the control group had a greater degree of hypotension during sepsis (68 vs 81 mm Hg; p = 0.003) and a reduction in the early polyuric response (from 496 to 160 mL at 2-8 hr of sepsis; p < 0.001). Creatinine clearance decreased similarly in both groups. CONCLUSIONS In experimental hyperdynamic sepsis, renal denervation was associated with greater hypotension and a loss of the initial diuresis, but no significant change in creatinine clearance. In sepsis, the renal nerves help support arterial pressure and determine the initial diuretic response, but septic acute kidney injury developed similarly in the innervated and denervated groups.
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Abstract
The renin-angiotensin system (RAS) is critically involved in the regulation of the salt and volume status of the body and blood pressure. The activity of the RAS is controlled by the protease renin, which is released from the renal juxtaglomerular epithelioid cells into the circulation. Renin release is regulated in negative feedback-loops by blood pressure, salt intake, and angiotensin II. Moreover, sympathetic nerves and renal autacoids such as prostaglandins and nitric oxide stimulate renin secretion. Despite numerous studies there remained substantial gaps in the understanding of the control of renin release at the organ or cellular level. Some of these gaps have been closed in the last years by means of gene-targeted mice and advanced imaging and electrophysiological methods. In our review, we discuss these recent advances together with the relevant previous literature on the regulation of renin release.
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Lohmeier TE, Hildebrandt DA, Dwyer TM, Barrett AM, Irwin ED, Rossing MA, Kieval RS. Renal denervation does not abolish sustained baroreflex-mediated reductions in arterial pressure. Hypertension 2006; 49:373-9. [PMID: 17159083 DOI: 10.1161/01.hyp.0000253507.56499.bb] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent studies indicate that suppression of renal sympathetic nerve activity and attendant increments in renal excretory function are sustained baroreflex-mediated responses in hypertensive animals. Given the central role of the kidneys in long-term regulation of arterial pressure, we hypothesized that the chronic blood pressure-lowering effects of the baroreflex are critically dependent on intact renal innervation. This hypothesis was tested in 6 dogs by bilaterally activating the carotid baroreflex electrically for 7 days before and after bilateral renal denervation. Before renal denervation, control values for mean arterial pressure and plasma norepinephrine concentration were 95+/-2 mm Hg and 96+/-12 pg/mL, respectively. During day 1 of baroreflex activation, mean arterial pressure decreased 13+/-1 mm Hg, and there was modest sodium retention. Daily sodium balance was subsequently restored, but reductions in mean arterial pressure were sustained throughout the 7 days of baroreflex activation. Activation of the baroreflex was associated with sustained decreases in plasma norepinephrine concentration ( approximately 50%) and plasma renin activity (30% to 40%). All of the values returned to control levels during a 7-day recovery period. Two weeks after renal denervation, control values for mean arterial pressure, plasma norepinephrine concentration, plasma renin activity, and sodium excretion were comparable to those measured when the renal nerves were intact. Moreover, after renal denervation, all of the responses to activation of the baroreflex were similar to those observed before renal denervation. These findings demonstrate that the presence of the renal nerves is not an obligate requirement for achieving long-term reductions in arterial pressure during prolonged activation of the baroreflex.
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Affiliation(s)
- Thomas E Lohmeier
- Department of Physiology, University of Mississippi Medical Center, 2500 North State St, Jackson, MS 39216-4505, USA.
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Mertz HL, Liu J, Valego NK, Stallings SP, Figueroa JP, Rose JC. Inhibition of cyclooxygenase-2: effects on renin secretion and expression in fetal lambs. Am J Physiol Regul Integr Comp Physiol 2003; 284:R1012-8. [PMID: 12456386 DOI: 10.1152/ajpregu.00523.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The importance of prostaglandins in the regulation of the renin-angiotensin system during development is not known. These experiments were conducted to examine the effects of prostaglandin synthesis inhibitors on basal and isoproterenol-induced plasma renin concentration and renin gene expression in the late-gestation fetal lamb. Eighteen lamb fetuses ranging in gestational age from 129 to 138 days underwent surgical insertion of femoral arterial and venous catheters under general endotracheal anesthesia. After a period of recovery, animals underwent an infusion of isoproterenol after administration of a saline bolus (control experiments); 24-48 h later a second study was performed after administration of NS-398, a cyclooxygenase (COX)-2 inhibitor, or saline for a second control study. Administration of COX-2 inhibitor significantly reduced baseline plasma renin levels and attenuated responses in fetal renin secretion to isoproterenol infusions. Renal cortical cells from animals receiving COX-2 inhibitor had significantly lower levels of renin mRNA compared with animals receiving only saline. Renal cortical cells in culture from animals receiving only saline exhibited increased levels of renin mRNA when treated with isoproterenol, forskolin, or IBMX. Only forskolin increased renin mRNA levels in renal cortical cells in culture from animals receiving COX-2 inhibitor. We conclude that prostaglandins play a stimulatory role in the regulation of the renin-angiotensin system and are necessary for beta-adrenergic stimulation of renin secretion and gene expression in the late-gestation fetal lamb.
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Affiliation(s)
- Heather L Mertz
- Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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Rosnes JS, Valego N, Wang JJ, Perez FM, Rose JC. Renal mRNA response to reduced perfusion pressure conserved despite denervation in mature ovine fetuses. Am J Physiol Regul Integr Comp Physiol 2001; 280:R1830-6. [PMID: 11353689 DOI: 10.1152/ajpregu.2001.280.6.r1830] [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: 11/22/2022]
Abstract
We hypothesized that renal denervation in mature ovine fetuses reduces renin mRNA response to 24 h of reduced renal perfusion pressure (RPP). Seven occluder (O) (132.4 ± 1.2 days gestation) and six control (C) (131.5 ± 1.2 days gestation) fetuses underwent left renal denervation. Postoperatively, O fetuses experienced 24 h of reduced RPP by suprarenal aortic occlusion. Femoral arterial blood pressure (FAB) and plasma active renin (pARC) and prorenin (pPRC) concentrations were obtained hourly for 6 h and at h 23 and 24. Renin mRNA was measured by RNase protection assay. We quantitated renin containing glomeruli by immunocytochemistry. Variables were compared by ANOVA. Mean O group FAB reduction from baseline was −6.60 ± 0.41 mmHg. pARC and pPRC increased with occlusion, renal ARC and renal PRC 1 did not increase with occlusion. No effect in renin mRNA or number of positive glomeruli was noted with denervation in the basal state; however, significant increases were noted in response to RPP irrespective of innervation status. In conclusion, 24 h or reduced RPP in mature ovine fetus increases renal renin mRNA and the immunocytochemical expression of renin. This response is conserved despite denervation.
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Affiliation(s)
- J S Rosnes
- Department of Obstetrics and Gynecology, Perinatal Research Laboratories, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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Abstract
1. The importance of renal sympathetic nerve activity (RSNA) in the regulation of renal function is well established. However, it is less clear how the renal vasculature responds to the different mean levels and patterns of RSNA. While many studies have indicated that small to moderate changes in RSNA preferentially regulate renin secretion or sodium excretion and only large changes in RSNA regulate renal blood flow (RBF), other experimental evidence suggests that small changes in RSNA can influence RBF 2. When RSNA has been directly measured in conjunction with RBF, it appears that a range of afferent stimuli can induce reflex changes in RBF. However, many studies in a variety of species have measured RBF only during stimuli designed to reflexly increase or decrease sympathetic activity, but have not recorded RSNA. While this approach can be informative, it is not definitive because the ability of the vasculature to respond to RSNA may, in part, reflect the resting level of RSNA and, therefore, the vasoconstrictive state of the vasculature under the control conditions. 3. Further understanding of the control of RBF by RSNA has come from studies that have analysed the underlying rhythms in sympathetic nerve activity and their effect on the cardiovascular system. These studies show that the frequency-response characteristic of the renal vasculature is such that higher frequency oscillations in RSNA (above 0.6 Hz) contribute to setting the mean level of RBF. In comparison, lower frequency oscillations in RSNA can induce cyclic vasoconstriction and dilation in the renal vasculature, thus inducing oscillations in RBF. 4. In summary, the present review discusses the neural control of RBF, summarizing evidence in support of the hypothesis that RBF is under the influence of RSNA across the full range of RSNA.
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Affiliation(s)
- S C Malpas
- Department of Physiology, University of Auckland, New Zealand.
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Wagner C, Hinder M, Krämer BK, Kurtz A. Role of renal nerves in the stimulation of the renin system by reduced renal arterial pressure. Hypertension 1999; 34:1101-5. [PMID: 10567189 DOI: 10.1161/01.hyp.34.5.1101] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this study was to determine the role of renal innervation in the prolonged stimulation of renin secretion and renin synthesis accompanying renal artery stenosis. Male Sprague-Dawley rats, in which the left kidney had been denervated or sham denervated 4 days earlier, received a left renal artery clip (ID 0.2 mm). Plasma renin activity and renin mRNA were assayed 1, 2, or 4 days after clipping. The stimulation of both plasma renin activity and renin mRNA was blunted markedly in the rats with the denervated clipped kidney. The typical suppression of renin mRNA in the intact right kidney, however, was not different between rats with sham-denervated or denervated left kidneys, nor was the increase of blood pressure in response to renal artery clipping different between the experimental groups. To test whether the suppression of renin mRNA in the contralateral kidney was related to the increase of blood pressure, another group of rats with denervated clipped left kidneys was treated additionally with the T-type calcium channel blocker mibefradil (15 mg. kg(-1). d(-1)). Despite blood pressure normalization by mibefradil, plasma renin activities and renin mRNA levels in the clipped denervated kidneys and in the intact right kidneys remained unchanged. These findings suggest that renal nerves are responsible for marked background stimulation of both renin secretion and renin mRNA expression, which is normally masked by the inhibitory effect of renal perfusion pressure on the renin system. Renal nerve activity is therefore an important determinant of the gain of renin stimulation during reduced renal arterial pressure.
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Affiliation(s)
- C Wagner
- Institut für Physiologie, Universität Regensburg, (Germany).
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Rosnes JS, Valego N, Wang J, Zehnder T, Rose JC. Active renin, prorenin, and renin gene expression after reduced renal perfusion pressure in term ovine fetuses. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R141-7. [PMID: 9688972 DOI: 10.1152/ajpregu.1998.275.1.r141] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We studied the pattern of plasma active renin concentration (ARC), prorenin concentration (PRC), renal renin concentration, and the renin mRNA levels in ovine fetuses subjected for 24 h to reduced renal perfusion pressure (RPP). The results obtained in five animals (133.8 +/- 1.4 days of gestation) in which RPP was reduced by 10 mmHg were compared with those in seven control fetuses (130.3 +/- 0. 8 days of gestation) without pressure reduction. Plasma samples were obtained before and at intervals of 24 h after initiating reduced RPP. The plasma ARC increased within 60 min of reduced RPP, reaching a maximum (13.0 +/- 4.7 vs. 115.7 +/- 23.8, P < 0.01) at 3 h. The ARC then declined toward control values. In contrast, plasma PRC did not increase consistently until 4 h into reduced RPP, with maximal levels at 24 h (8.2 +/- 2.4 vs. 87.7 +/- 21.9, P = 0.016). Within the kidney PRC, but not ARC, increased significantly, by 2.5-fold. Reduced RPP also increased renal renin mRNA levels (P = 0.004). We conclude that a chronic reduction in RPP in the near-term ovine fetus increases renal PRC and is associated with increased plasma prorenin levels. The data suggest that the conversion of prorenin to active renin is an important regulation point of the renin ANG system during development.
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Affiliation(s)
- J S Rosnes
- Department of Obstetrics/Gynecology, Bowman Gray School of Medicine, Winston-Salem, North Carolina 27157, USA
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