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AlMarabeh S, Abdulla MH, O'Halloran KD. Is Aberrant Reno-Renal Reflex Control of Blood Pressure a Contributor to Chronic Intermittent Hypoxia-Induced Hypertension? Front Physiol 2019; 10:465. [PMID: 31105584 PMCID: PMC6491928 DOI: 10.3389/fphys.2019.00465] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 04/04/2019] [Indexed: 12/16/2022] Open
Abstract
Renal sensory nerves are important in the regulation of body fluid and electrolyte homeostasis, and blood pressure. Activation of renal mechanoreceptor afferents triggers a negative feedback reno-renal reflex that leads to the inhibition of sympathetic nervous outflow. Conversely, activation of renal chemoreceptor afferents elicits reflex sympathoexcitation. Dysregulation of reno-renal reflexes by suppression of the inhibitory reflex and/or activation of the excitatory reflex impairs blood pressure control, predisposing to hypertension. Obstructive sleep apnoea syndrome (OSAS) is causally related to hypertension. Renal denervation in patients with OSAS or in experimental models of chronic intermittent hypoxia (CIH), a cardinal feature of OSAS due to recurrent apnoeas (pauses in breathing), results in a decrease in circulating norepinephrine levels and attenuation of hypertension. The mechanism of the beneficial effect of renal denervation on blood pressure control in models of CIH and OSAS is not fully understood, since renal denervation interrupts renal afferent signaling to the brain and sympathetic efferent signals to the kidneys. Herein, we consider the currently proposed mechanisms involved in the development of hypertension in CIH disease models with a focus on oxidative and inflammatory mediators in the kidneys and their potential influence on renal afferent control of blood pressure, with wider consideration of the evidence available from a variety of hypertension models. We draw focus to the potential contribution of aberrant renal afferent signaling in the development, maintenance and progression of high blood pressure, which may have relevance to CIH-induced hypertension.
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Affiliation(s)
- Sara AlMarabeh
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Mohammed H Abdulla
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
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Peng H, Jensen DD, Li W, Sullivan MN, Buller SA, Worker CJ, Cooper SG, Zheng S, Earley S, Sigmund CD, Feng Y. Overexpression of the neuronal human (pro)renin receptor mediates angiotensin II-independent blood pressure regulation in the central nervous system. Am J Physiol Heart Circ Physiol 2018; 314:H580-H592. [PMID: 29350998 PMCID: PMC5899258 DOI: 10.1152/ajpheart.00310.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 12/06/2017] [Accepted: 12/06/2017] [Indexed: 11/22/2022]
Abstract
Despite advances in antihypertensive therapeutics, at least 15-20% of hypertensive patients have resistant hypertension through mechanisms that remain poorly understood. In this study, we provide a new mechanism for the regulation of blood pressure (BP) in the central nervous system (CNS) by the (pro)renin receptor (PRR), a recently identified component of the renin-angiotensin system that mediates ANG II formation in the CNS. Although PRR also mediates ANG II-independent signaling, the importance of these pathways in BP regulation is unknown. Here, we developed a unique transgenic mouse model overexpressing human PRR (hPRR) specifically in neurons (Syn-hPRR). Intracerebroventricular infusion of human prorenin caused increased BP in Syn-hPRR mice. This BP response was attenuated by a NADPH oxidase (NOX) inhibitor but not by antihypertensive agents that target the renin-angiotensin system. Using a brain-targeted genetic knockdown approach, we found that NOX4 was the key isoform responsible for the prorenin-induced elevation of BP in Syn-hPRR mice. Moreover, inhibition of ERK significantly attenuated the increase in NOX activity and BP induced by human prorenin. Collectively, our findings indicate that an ANG II-independent, PRR-mediated signaling pathway regulates BP in the CNS by a PRR-ERK-NOX4 mechanism. NEW & NOTEWORTHY This study characterizes a new transgenic mouse model with overexpression of the human (pro)renin receptor in neurons and demonstrated a novel angiotensin II-independent mechanism mediated by human prorenin and the (pro)renin receptor in the central regulation of blood pressure.
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Affiliation(s)
- Hua Peng
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huangzhong University of Sciences and Technology , Wuhan, Hubei , China
| | - Dane D Jensen
- Department of Physiology & Cell Biology, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
| | - Wencheng Li
- Department of Pathology, Wake Forest University School of Medicine , Winston-Salem, North Carolina
| | - Michelle N Sullivan
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Department of Pharmacology, University of Nevada, Reno, School of Medicine , Reno, Nevada
| | - Sophie A Buller
- Department of Physiology & Cell Biology, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Department of Pharmacology, University of Nevada, Reno, School of Medicine , Reno, Nevada
| | - Caleb J Worker
- Department of Physiology & Cell Biology, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Department of Pharmacology, University of Nevada, Reno, School of Medicine , Reno, Nevada
| | - Silvana G Cooper
- Department of Physiology & Cell Biology, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Department of Pharmacology, University of Nevada, Reno, School of Medicine , Reno, Nevada
| | - Shiqi Zheng
- Department of Neurosurgery, Beijing Luhe Hospital, Capital Medical University , Beijing , China
| | - Scott Earley
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Department of Pharmacology, University of Nevada, Reno, School of Medicine , Reno, Nevada
| | - Curt D Sigmund
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa , Iowa City, Iowa
| | - Yumei Feng
- Department of Physiology & Cell Biology, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Center for Cardiovascular Research, University of Nevada, Reno, School of Medicine , Reno, Nevada
- Department of Pharmacology, University of Nevada, Reno, School of Medicine , Reno, Nevada
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The role of brain angiotensin II (type 2) receptors and nitric oxide in the renal sympathoinhibitory response to acute volume expansion in conscious rats. J Hypertens 2017; 35:338-347. [PMID: 27820727 DOI: 10.1097/hjh.0000000000001154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE The study was performed to investigate the role of angiotensin II type 2 (AT2) receptors and nitric oxide in the renal sympathoinhibitory response to volume expansion (VEP). METHOD Conscious rats were subjected to volume expansion (VEP) [0.25% body weight/min saline for 10 min intravenously (i.v.)] following intracerebroventricular (i.c.v.) infusion of either saline or angiotensin II (Ang II), or a combination of Ang II with either losartan, PD123319, or N-nitro-L-arginine methyl ester (L-NAME). RESULTS Intracerebroventricular losartan, PD123319, or L-NAME did not change baseline mean arterial pressure, heart rate, or renal sympathetic nerve activity (RSNA). However, i.c.v. Ang II increased mean arterial pressure and decreased heart rate and RSNA baselines (113 ± 2 vs. 107 ± 2 mmHg, 365 ± 7 vs. 379 ± 5 beats/min, 1.03 ± 0.13 vs. 1.29 ± 0.15 μV.s, respectively, all P < 0.05). During i.c.v. saline infusion, VEP decreased RSNA by 27 ± 2% (P < 0.05) after 10 min and the magnitude of this response was unchanged during i.c.v. infusion of Ang II, losartan, or PD123319 but was decreased by L-NAME compared with that obtained with i.c.v. saline (14 ± 3 vs. 30 ± 5%, P < 0.05). i.c.v. Ang II in combination with losartan enhanced (41 ± 3 vs. 29 ± 5%) but with PD123319 decreased (15 ± 2 vs. 28 ± 4%, P < 0.05) the renal sympathoinhibition compared with Ang II alone. The renal sympathoinhibitory response was enhanced (43 ± 5 vs. 29 ± 1%, P < 0.05) by i.c.v. infusion of an AT2 agonist, CGP42112 the magnitude of which was unchanged when combined with L-NAME. The sympathoinhibitory response to VEP following Ang II plus L-NAME was similar to Ang II alone. CONCLUSION These findings suggest that activation of central AT2 receptors enhances the renal sympathoinhibitory response to VEP but this effect is not dependent on nitric oxide.
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Summertime dosage-dependent hypersensitivity to an angiotensin II receptor blocker. BMC Res Notes 2015; 8:227. [PMID: 26055103 PMCID: PMC4467666 DOI: 10.1186/s13104-015-1215-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 05/29/2015] [Indexed: 01/08/2023] Open
Abstract
Background Summertime dips in blood pressure (BP), both in normotensive and hypertensive subjects, are well known. However, the dips are small and are not related to particular forms or doses of antihypertensive medication. Nevertheless it is the practice in some quarters to decrease antihypertensive medication in summer, and/or to increase in winter. Large scale studies being inconclusive, there are calls for long-term examination of the relationship between environmental temperature and blood pressure in single individuals under medication. Case presentation While analyzing data from a subject whose BP had been controlled for a decade with the angiotensin-II receptor blocker losartan, an extreme, dosage-dependent, summertime dip came to light. Downward dosage adjustment appeared essential and may have prevented hypotension-related pathology. Conclusion The benefits of aggressive medication (the “J curve” phenomenon) being debated, the possibility of seasonal hypersensitivity, perhaps explicable in terms of differential signaling by countervailing receptors, should be taken into account when considering dosage adjustments in hypertensive subjects.
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Derad I, Sayk F, Lehnert H, Marshall L, Born J, Nitschke M. Intranasal Angiotensin II in Humans Reduces Blood Pressure When Angiotensin II Type 1 Receptors Are Blocked. Hypertension 2014; 63:762-7. [DOI: 10.1161/hypertensionaha.113.02860] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Intranasal administration of angiotensin II (ANGII) affects blood pressure in a mode different from intravenously administered ANGII via a direct access to the brain bypassing the blood–brain barrier. This clinical study investigated blood pressure regulation after intranasal ANGII administration in healthy humans, whereas systemic, blood-mediated effects of ANGII were specifically blocked. In a balanced crossover design, men (n=8) and women (n=8) were intranasally administered ANGII (400 μg) or placebo after ANGII type 1 receptors had been blocked by pretreatment with valsartan (80 mg; 12 and 6 hours before intranasal administration). Plasma levels of ANGII, aldosterone, renin, vasopressin, and norepinephrine were measured; blood pressure and heart rate were recorded continuously. Intranasal ANGII acutely decreased blood pressure without altering the heart rate. Plasma levels of vasopressin and norepinephrine remained unaffected. Plasma ANGII levels were increased throughout the recording period. Aldosterone levels increased despite the peripheral ANGII type 1 receptor blockade, indicating an aldosterone escape phenomenon. In conclusion, intranasal ANGII reduces blood pressure in the presence of selective ANGII type 1 receptor blockade. Intranasal ANGII administration represents a useful approach for unraveling the role of this peptide in blood pressure regulation in humans.
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Affiliation(s)
- Inge Derad
- From the Department of Internal Medicine (I.D., F.S., H.L., M.N.) and Department of Neuroendocrinology (L.M.), University of Lübeck, Lübeck, Germany; and Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany (J.B.)
| | - Friedhelm Sayk
- From the Department of Internal Medicine (I.D., F.S., H.L., M.N.) and Department of Neuroendocrinology (L.M.), University of Lübeck, Lübeck, Germany; and Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany (J.B.)
| | - Hendrik Lehnert
- From the Department of Internal Medicine (I.D., F.S., H.L., M.N.) and Department of Neuroendocrinology (L.M.), University of Lübeck, Lübeck, Germany; and Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany (J.B.)
| | - Lisa Marshall
- From the Department of Internal Medicine (I.D., F.S., H.L., M.N.) and Department of Neuroendocrinology (L.M.), University of Lübeck, Lübeck, Germany; and Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany (J.B.)
| | - Jan Born
- From the Department of Internal Medicine (I.D., F.S., H.L., M.N.) and Department of Neuroendocrinology (L.M.), University of Lübeck, Lübeck, Germany; and Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany (J.B.)
| | - Martin Nitschke
- From the Department of Internal Medicine (I.D., F.S., H.L., M.N.) and Department of Neuroendocrinology (L.M.), University of Lübeck, Lübeck, Germany; and Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany (J.B.)
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Wainford RD. Angiotensin AT2 receptors and the baroreflex control of renal sympathetic nerve activity. Acta Physiol (Oxf) 2014; 210:714-6. [PMID: 24447624 DOI: 10.1111/apha.12240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. D. Wainford
- Department of Pharmacology & Experimental Therapeutics; Boston University School of Medicine; Boston MA USA
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Abdulla MH, Johns EJ. Nitric oxide impacts on angiotensin AT2 receptor modulation of high-pressure baroreflex control of renal sympathetic nerve activity in anaesthetized rats. Acta Physiol (Oxf) 2014; 210:832-44. [PMID: 24279649 PMCID: PMC3992911 DOI: 10.1111/apha.12207] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 09/30/2013] [Accepted: 11/19/2013] [Indexed: 11/28/2022]
Abstract
Aim Nitric oxide (NO) interacts with the local brain renin-angiotensin system to modulate sympathetic outflow and cardiovascular homoeostasis. This study investigated whether NO influenced the ability of angiotensin AT2 receptor activation to modify the high-pressure baroreceptor regulation of renal sympathetic nerve activity (RSNA) and heart rate (HR). Methods Anaesthetized (chloralose/urethane) rats were prepared to allow generation of baroreflex gain curves for RSNA or HR following intracerebroventricular (I.C.V.) CGP42112 (AT2 receptor agonist), PD123319 (AT2 receptor antagonist) or losartan (AT1 receptor antagonist), and then in combination with L-NAME (NO synthase inhibitor). Results I.C.V. PD123319, CGP42112, and Losartan did not change baseline mean arterial pressure, HR or RSNA. Baroreflex sensitivities for RSNA and HR were increased following AT2 receptor activation with CGP42112 by 112 and 157%, respectively, but were reduced following PD123319 by 20% (all P < 0.05). L-NAME alone increased baroreflex sensitivity for both RSNA and HR, by 62 and 158%, respectively, but when co-infused with either CGP42112 or PD123319, the baroreflex sensitivity fell to values comparable to those obtained during I.C.V. saline infusion. The baroreflex sensitivities for RSNA and HR were increased by losartan by 92% and 192%, respectively, but in the presence of L-NAME were no different from those obtained during I.C.V. saline infusion. Conclusion There is an important facilitatory role for AT2 receptors in the high-pressure baroreflex regulation of RSNA and HR which is dependent on a functional NO/NOS system. Conversely, AT1 receptors have an inhibitory effect on the baroreflex, an action that relies on a tonic inhibition of NO.
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Affiliation(s)
- M. H. Abdulla
- Department of Physiology Western Gateway Building University College Cork Cork Ireland
| | - E. J. Johns
- Department of Physiology Western Gateway Building University College Cork Cork Ireland
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