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Wu J, Le TH. Autoregulatory mission impossible: when afferent arterioles lose contractility. Kidney Int 2023; 104:649-651. [PMID: 37739614 PMCID: PMC10860642 DOI: 10.1016/j.kint.2023.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 07/19/2023] [Accepted: 07/21/2023] [Indexed: 09/24/2023]
Abstract
The myogenic response of afferent arterioles is a key autoregulatory mechanism that protects the glomeruli from barotrauma. Afferent arteriolar smooth muscle cells contract to increased intraluminal pressure through mechanosensitive cation channels and interactions between integrin and extracellular matrix that trigger calcium-dependent actomyosin contraction. The study by Feng et al. provides evidence supporting the concept that increased matrix metalloproteinase 9 in kidney microvessels of Dahl salt-sensitive rats interferes with integrin-matrix binding and promotes phenotypic transformation of afferent arterioles, causing loss of myogenic constriction and hypertensive nephropathy.
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Affiliation(s)
- Jing Wu
- Division of Nephrology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA; Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Thu H Le
- Division of Nephrology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA.
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2
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Purinoceptor: a novel target for hypertension. Purinergic Signal 2023; 19:185-197. [PMID: 35181831 PMCID: PMC9984596 DOI: 10.1007/s11302-022-09852-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/08/2022] [Indexed: 12/11/2022] Open
Abstract
Hypertension is the leading cause of morbidity and mortality globally among all cardiovascular diseases. Purinergic signalling plays a crucial role in hypertension through the sympathetic nerve system, neurons in the brain stem, carotid body, endothelium, immune system, renin-angiotensin system, sodium excretion, epithelial sodium channel activity (ENaC), and renal autoregulation. Under hypertension, adenosine triphosphate (ATP) is released as a cotransmitter from the sympathetic nerve. It mediates vascular tone mainly through P2X1R activation on smooth muscle cells and activation of P2X4R and P2YR on endothelial cells and also via interaction with other purinoceptors, showing dual effects. P2Y1R is linked to neurogenic hypertension. P2X7R and P2Y11R are potential targets for immune-related hypertension. P2X3R located on the carotid body is the most promising novel therapeutic target for hypertension. A1R, A2AR, A2BR, and P2X7R are all related to renal autoregulation, which contribute to both renal damage and hypertension. The main focus is on the evidence addressing the involvement of purinoceptors in hypertension and therapeutic interventions.
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Feng W, Remedies CE, Obi IE, Aldous SR, Meera SI, Sanders PW, Inscho EW, Guan Z. Restoration of afferent arteriolar autoregulatory behavior in ischemia-reperfusion injury in rat kidneys. Am J Physiol Renal Physiol 2021; 320:F429-F441. [PMID: 33491564 PMCID: PMC7988813 DOI: 10.1152/ajprenal.00500.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/23/2020] [Accepted: 01/12/2021] [Indexed: 12/11/2022] Open
Abstract
Renal autoregulation is critical in maintaining stable renal blood flow (RBF) and glomerular filtration rate (GFR). Renal ischemia-reperfusion (IR)-induced kidney injury is characterized by reduced RBF and GFR. The mechanisms contributing to renal microvascular dysfunction in IR have not been fully determined. We hypothesized that increased reactive oxygen species (ROS) contributed to impaired renal autoregulatory capability in IR rats. Afferent arteriolar autoregulatory behavior was assessed using the blood-perfused juxtamedullary nephron preparation. IR was induced by 60 min of bilateral renal artery occlusion followed by 24 h of reperfusion. Afferent arterioles from sham rats exhibited normal autoregulatory behavior. Stepwise increases in perfusion pressure caused pressure-dependent vasoconstriction to 65 ± 3% of baseline diameter (13.2 ± 0.4 μm) at 170 mmHg. In contrast, pressure-mediated vasoconstriction was markedly attenuated in IR rats. Baseline diameter averaged 11.7 ± 0.5 µm and remained between 90% and 101% of baseline over 65-170 mmHg, indicating impaired autoregulatory function. Acute antioxidant administration (tempol or apocynin) to IR kidneys for 20 min increased baseline diameter and improved autoregulatory capability, such that the pressure-diameter profiles were indistinguishable from those of sham kidneys. Furthermore, the addition of polyethylene glycol superoxide dismutase or polyethylene glycol-catalase to the perfusate blood also restored afferent arteriolar autoregulatory responsiveness in IR rats, indicating the involvement of superoxide and/or hydrogen peroxide. IR elevated mRNA expression of NADPH oxidase subunits and monocyte chemoattractant protein-1 in renal tissue homogenates, and this was prevented by tempol pretreatment. These results suggest that ROS accumulation, likely involving superoxide and/or hydrogen peroxide, impairs renal autoregulation in IR rats in a reversible fashion.NEW & NOTEWORTHY Renal ischemia-reperfusion (IR) leads to renal microvascular dysfunction manifested by impaired afferent arteriolar autoregulatory efficiency. Acute administration of scavengers of reactive oxygen species, polyethylene glycol-superoxide dismutase, or polyethylene glycol-catalase following renal IR restored afferent arteriolar autoregulatory capability in IR rats, indicating that renal IR led to reversible impairment of afferent arteriolar autoregulatory capability. Intervention with antioxidant treatment following IR may improve outcomes in patients by preserving renovascular autoregulatory function and potentially preventing the progression to chronic kidney disease after acute kidney injury.
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Affiliation(s)
- Wenguang Feng
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Colton E Remedies
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Ijeoma E Obi
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Stephen R Aldous
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Samia I Meera
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Paul W Sanders
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Veterans Affairs Medical Center, Birmingham, Alabama
| | - Edward W Inscho
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Zhengrong Guan
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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Guan Z, Makled MN, Inscho EW. Purinoceptors, renal microvascular function and hypertension. Physiol Res 2020; 69:353-369. [PMID: 32301620 DOI: 10.33549/physiolres.934463] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Proper renal blood flow (RBF) and glomerular filtration rate (GFR) are critical for maintaining normal blood pressure, kidney function and water and electrolyte homeostasis. The renal microvasculature expresses a multitude of receptors mediating vasodilation and vasoconstriction, which can influence glomerular blood flow and capillary pressure. Despite this, RBF and GFR remain quite stable when arterial pressure fluctuates because of the autoregulatory mechanism. ATP and adenosine participate in autoregulatory control of RBF and GFR via activation of two different purinoceptor families (P1 and P2). Purinoceptors are widely expressed in renal microvasculature and tubules. Emerging data show altered purinoceptor signaling in hypertension-associated kidney injury, diabetic nephropathy, sepsis, ischemia-reperfusion induced acute kidney injury and polycystic kidney disease. In this brief review, we highlight recent studies and new insights on purinoceptors regulating renal microvascular function and renal hemodynamics. We also address the mechanisms underlying renal microvascular injury and impaired renal autoregulation, focusing on purinoceptor signaling and hypertension-induced renal microvascular dysfunction. Interested readers are directed to several excellent and comprehensive reviews that recently covered the topics of renal autoregulation, and nucleotides in kidney function under physiological and pathophysiological conditions (Inscho 2009, Navar et al. 2008, Carlstrom et al. 2015, Vallon et al. 2020).
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Affiliation(s)
- Z Guan
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, South Birmingham, USA.
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5
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Van Beusecum JP, Zhang S, Beltran E, Cook AK, Tobin RP, Newell-Rogers MK, Inscho EW. Antagonism of major histocompatibility complex class II invariant chain peptide during chronic lipopolysaccharide treatment rescues autoregulatory behavior. Am J Physiol Renal Physiol 2019; 317:F957-F966. [PMID: 31432707 DOI: 10.1152/ajprenal.00164.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Toll-like receptor 4 (TLR4) activation contributes to vascular dysfunction in pathological conditions such as hypertension and diabetes, but the role of chronic TLR4 activation on renal autoregulatory behavior is unknown. We hypothesized that subclinical TLR4 stimulation with low-dose lipopolysaccharide (LPS) infusion increases TLR4 activation and blunts renal autoregulatory behavior. We assessed afferent arteriolar autoregulatory behavior in male Sprague-Dawley rats after prolonged LPS (0.1 mg·kg-1·day-1 sq) infusion via osmotic minipump for 8 or 14 days. Some rats also received daily cotreatment with either anti-TLR4 antibody (1 μg ip), competitive antagonist peptide (CAP; 3 mg/kg ip) or tempol (2 mmol/l, drinking water) throughout the 8-day LPS treatment period. Autoregulatory behavior was assessed using the in vitro blood-perfused juxtamedullary nephron preparation. Selected physiological measures, systolic blood pressure and baseline diameters were normal and similar across groups. Pressure-dependent vasoconstriction averaged 72 ± 2% of baseline in sham rats, indicating intact autoregulatory behavior. Eight-day LPS-treated rats exhibited significantly impaired pressure-mediated vasoconstriction (96 ± 1% of baseline), whereas it was preserved in rats that received anti-TLR4 antibody (75 ± 3%), CAP (84 ± 2%), or tempol (82 ± 2%). Using a 14-day LPS (0.1 mg·kg-1·day-1 sq) intervention protocol, CAP treatment started on day 7, where autoregulatory behavior is already impaired. Systolic blood pressures were normal across all treatment groups. Fourteen-day LPS treatment retained the autoregulatory impairment (95 ± 2% of baseline). CAP intervention starting on day 7 rescued pressure-mediated vasoconstriction with diameters decreasing to 85 ± 1% of baseline. These data demonstrate that chronic subclinical TLR4 activation impairs afferent arteriolar autoregulatory behavior through mechanisms involving reactive oxygen species and major histocompatibility complex class II activation.
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Affiliation(s)
- Justin P Van Beusecum
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Shali Zhang
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Estevan Beltran
- School of Natural Sciences, University of California, Merced, Merced, California
| | - Anthony K Cook
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Richard P Tobin
- Division of Surgical Oncology, Department of Surgery, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado
| | - M Karen Newell-Rogers
- Department of Medical Physiology, Department of Medicine, Texas A&M Health Science Center, Temple, Texas
| | - Edward W Inscho
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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Zhou Z, Matsumoto T, Jankowski V, Pernow J, Mustafa SJ, Duncker DJ, Merkus D. Uridine adenosine tetraphosphate and purinergic signaling in cardiovascular system: An update. Pharmacol Res 2019; 141:32-45. [PMID: 30553823 PMCID: PMC6685433 DOI: 10.1016/j.phrs.2018.12.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/26/2018] [Accepted: 12/12/2018] [Indexed: 02/07/2023]
Abstract
Uridine adenosine tetraphosphate (Up4A), biosynthesized by activation of vascular endothelial growth factor receptor (VEGFR) 2, was initially identified as a potent endothelium-derived vasoconstrictor in perfused rat kidney. Subsequently, the effect of Up4A on vascular tone regulation was intensively investigated in arteries isolated from different vascular beds in rodents including rat pulmonary arteries, aortas, mesenteric and renal arteries as well as mouse aortas, in which Up4A produces vascular contraction. In contrast, Up4A produces vascular relaxation in porcine coronary small arteries and rat aortas. Intravenous infusion of Up4A into conscious rats or mice decreases blood pressure, and intravenous bolus injection of Up4A into anesthetized mice increases coronary blood flow, indicating an overall vasodilator influence in vivo. Although Up4A is the first dinucleotide described that contains both purine and pyrimidine moieties, its cardiovascular effects are exerted mainly through activation of purinergic receptors. These effects not only encompass regulation of vascular tone, but also endothelial angiogenesis, smooth muscle cell proliferation and migration, and vascular calcification. Furthermore, this review discusses a potential role for Up4A in cardiovascular pathophysiology, as plasma levels of Up4A are elevated in juvenile hypertensive patients and Up4A-mediated vascular purinergic signaling changes in cardiovascular disease such as hypertension, diabetes, atherosclerosis and myocardial infarction. Better understanding the vascular effect of the novel dinucleotide Up4A and the purinergic signaling mechanisms mediating its effects will enhance its potential as target for treatment of cardiovascular disease.
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Affiliation(s)
- Zhichao Zhou
- Division of Cardiology, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
| | - Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
| | - Vera Jankowski
- RWTH-Aachen, Institute for Molecular Cardiovascular Research, Aachen, Germany
| | - John Pernow
- Division of Cardiology, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden
| | - S Jamal Mustafa
- Department of Physiology, Pharmacology & Neuroscience, Center for Cardiovascular and Respiratory Sciences, Clinical and Translational Science Institute, West Virginia University, Morgantown, WV, United States
| | - Dirk J Duncker
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Erasmus University Medical Center, Rotterdam, the Netherlands
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Huang L, Wang A, Hao Y, Li W, Liu C, Yang Z, Zheng F, Zhou MS. Macrophage Depletion Lowered Blood Pressure and Attenuated Hypertensive Renal Injury and Fibrosis. Front Physiol 2018; 9:473. [PMID: 29867533 PMCID: PMC5949360 DOI: 10.3389/fphys.2018.00473] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 04/16/2018] [Indexed: 01/13/2023] Open
Abstract
Monocyte/macrophage recruitment is closely associated with the degree of hypertensive renal injury. We investigated the direct role of macrophages using liposome-encapsulated clodronate (LEC) to deplete monocytes/macrophages in hypertensive renal injury. C57BL/6 mice were treated with a pressor dose of angiotensin (Ang, 1.4 mg/kg/day) II plus LEC or the PBS-liposome for 2 weeks. Ang II mice developed hypertension, albuminuria, glomerulosclerosis, and renal fibrosis. LEC treatment reduced systolic blood pressure (SBP), albuminuria, and protected against renal structural injury in Ang II mice. Ang II significantly increased renal macrophage infiltration (MOMA2+ cells) and the expression of renal tumor necrosis factor α and interleukin β1, which were significantly reduced in Ang II/LEC mice. Ang II increased renal oxidative stress and the expression of profibrotic factors transforming growth factor (TGF) β1 and fibronectin. Ang II also inhibited the phosphorylation of endothelial nitric oxide synthase [phospho-endothelial nitric oxide synthesis (eNOS), ser1177]. LEC treatment reduced renal oxidative stress and TGFβ1 and fibronectin expressions, and increased phospho-eNOS expression in the Ang II mice. In Dahl rats of salt-sensitive hypertension, LEC treatment for 4 weeks significantly attenuated the elevation of SBP induced by high salt intake and protected against renal injury and fibrosis. Our results demonstrate that renal macrophages play a critical role in the development of hypertension and hypertensive renal injury and fibrosis; the underlying mechanisms may be involved in the reduction in macrophage-driven renal inflammation and restoration of the balance between renal oxidative stress and eNOS. Therefore, macrophages should be considered as a potential therapeutic target to reduce the adverse consequences of hypertensive renal diseases.
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Affiliation(s)
- Lei Huang
- Department of Physiology, Shenyang Medical University, Shenyang, China.,Department of Physiology, Jinzhou Medical University, Jinzhou, China
| | - Aimei Wang
- Department of Physiology, Jinzhou Medical University, Jinzhou, China
| | - Yun Hao
- Department of Physiology, Jinzhou Medical University, Jinzhou, China
| | - Weihong Li
- Department of Physiology, Jinzhou Medical University, Jinzhou, China
| | - Chang Liu
- Department of Endocrinology, First Affiliated Hospital of Jinzhou Medical University, Jinzhou, China
| | - Zhihang Yang
- Department of Physiology, Shenyang Medical University, Shenyang, China
| | - Feng Zheng
- Department of Nephrology, Second Affiliated Hospital of Dalian Medical University, Liaoning, China
| | - Ming-Sheng Zhou
- Department of Physiology, Shenyang Medical University, Shenyang, China.,Department of Physiology, Jinzhou Medical University, Jinzhou, China
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Guan Z, Wang F, Cui X, Inscho EW. Mechanisms of sphingosine-1-phosphate-mediated vasoconstriction of rat afferent arterioles. Acta Physiol (Oxf) 2018. [PMID: 28640982 DOI: 10.1111/apha.12913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
AIM Sphingosine-1-phosphate (S1P) influences resistance vessel function and is implicated in renal pathological processes. Previous studies revealed that S1P evoked potent vasoconstriction of the pre-glomerular microvasculature, but the underlying mechanisms remain incompletely defined. We postulated that S1P-mediated pre-glomerular microvascular vasoconstriction involves activation of voltage-dependent L-type calcium channels (L-VDCC) and the rho/rho kinase pathway. METHODS Afferent arteriolar reactivity was assessed in vitro using the blood-perfused rat juxtamedullary nephron preparation, and diameter was measured during exposure to physiological and pharmacological agents. RESULTS Exogenous S1P (10-9 -10-5 mol L-1 ) evoked concentration-dependent vasoconstriction of afferent arterioles. Superfusion with nifedipine, a L-VDCC blocker, increased arteriolar diameter by 39 ± 18% of baseline and significantly attenuated the S1P-induced vasoconstriction. Superfusion with the rho kinase inhibitor, Y-27632, increased diameter by 60 ± 12% of baseline and also significantly blunted vasoconstriction by S1P. Combined nifedipine and Y-27632 treatment significantly inhibited S1P-induced vasoconstriction over the entire concentration range tested. In contrast, depletion of intracellular Ca2+ stores with the Ca2+ -ATPase inhibitors, thapsigargin or cyclopiazonic acid, did not alter the S1P-mediated vasoconstrictor profile. Scavenging reactive oxygen species (ROS) or inhibition of nicotinamide adenine dinucleotide phosphate oxidase activity significantly attenuated S1P-mediated vasoconstriction. CONCLUSION Exogenous S1P elicits potent vasoconstriction of rat afferent arterioles. These data also demonstrate that S1P-mediated pre-glomerular vasoconstriction involves activation of L-VDCC, the rho/rho kinase pathway and ROS. Mobilization of Ca2+ from intracellular stores is not required for S1P-mediated vasoconstriction. These studies reveal a potential role for S1P in the modulation of renal microvascular tone.
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Affiliation(s)
- Z. Guan
- Division of Nephrology; Department of Medicine; University of Alabama at Birmingham; Birmingham AL USA
| | - F. Wang
- Department of Biostatistics; Ryals School of Public Health; University of Alabama at Birmingham; Birmingham AL USA
| | - X. Cui
- Department of Biostatistics; Ryals School of Public Health; University of Alabama at Birmingham; Birmingham AL USA
| | - E. W. Inscho
- Division of Nephrology; Department of Medicine; University of Alabama at Birmingham; Birmingham AL USA
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Van Beusecum JP, Zhang S, Cook AK, Inscho EW. Acute toll-like receptor 4 activation impairs rat renal microvascular autoregulatory behaviour. Acta Physiol (Oxf) 2017; 221:204-220. [PMID: 28544543 DOI: 10.1111/apha.12899] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/16/2016] [Accepted: 05/18/2017] [Indexed: 12/24/2022]
Abstract
AIM Little is known about how toll-like receptor 4 (TLR4) influences the renal microvasculature. We hypothesized that acute TLR4 stimulation with lipopolysaccharide (LPS) impairs afferent arteriole autoregulatory behaviour, partially through reactive oxygen species (ROS). METHODS We assessed afferent arteriole autoregulatory behaviour after LPS treatment (1 mg kg-1 ; i.p.) using the in vitro blood-perfused juxtamedullary nephron preparation. Autoregulatory behaviour was assessed by measuring diameter responses to stepwise changes in renal perfusion pressure. TLR4 expression was assessed by immunofluorescence, immunohistochemistry and Western blot analysis in the renal cortex and vasculature. RESULTS Baseline arteriole diameter at 100 mmHg averaged 15.2 ± 1.2 μm and 12.2 ± 1.0 μm for control and LPS groups (P < 0.05) respectively. When perfusion pressure was increased in 15 mmHg increments from 65 to 170 mmHg, arteriole diameter in control kidneys decreased significantly to 69 ± 6% of baseline diameter. In the LPS-treated group, arteriole diameter remained essentially unchanged (103 ± 9% of baseline), indicating impaired autoregulatory behaviour. Pre-treatment with anti-TLR4 antibody or the TLR4 antagonist, LPS-RS, preserved autoregulatory behaviour during LPS treatment. P2 receptor reactivity was normal in control and LPS-treated rats. Pre-treatment with Losartan (angiotensin type 1 receptor blocker; (AT1 ) 2 mg kg-1 ; i.p.) increased baseline afferent arteriole diameter but did not preserve autoregulatory behaviour in LPS-treated rats. Acute exposure to Tempol (10-3 mol L-1 ), a superoxide dismutase mimetic, restored pressure-mediated vasoconstriction in kidneys from LPS-treated rats. CONCLUSION These data demonstrate that TLR4 activation impairs afferent arteriole autoregulatory behaviour, partially through ROS, but independently of P2 and AT1 receptor activation.
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Affiliation(s)
- J. P. Van Beusecum
- Division of Nephrology; Department of Medicine; University of Alabama at Birmingham; Birmingham AL USA
- Department of Physiology; Augusta University; Augusta GA USA
| | - S. Zhang
- Division of Nephrology; Department of Medicine; University of Alabama at Birmingham; Birmingham AL USA
- Department of Physiology; Augusta University; Augusta GA USA
| | - A. K. Cook
- Division of Nephrology; Department of Medicine; University of Alabama at Birmingham; Birmingham AL USA
- Department of Physiology; Augusta University; Augusta GA USA
| | - E. W. Inscho
- Division of Nephrology; Department of Medicine; University of Alabama at Birmingham; Birmingham AL USA
- Department of Physiology; Augusta University; Augusta GA USA
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Zhou Z, Yadav VR, Sun C, Teng B, Mustafa JS. Impaired Aortic Contractility to Uridine Adenosine Tetraphosphate in Angiotensin II-Induced Hypertensive Mice: Receptor Desensitization? Am J Hypertens 2017; 30:304-312. [PMID: 28034895 PMCID: PMC5861566 DOI: 10.1093/ajh/hpw163] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/01/2016] [Accepted: 12/01/2016] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE We previously showed that uridine adenosine tetraphosphate (Up4A)-mediated aortic contraction is partly mediated through purinergic P2X1 receptors (P2X1R). It has been reported that the plasma level of Up4A is elevated in hypertensive patients, implying a potential role for Up4A-P2X1R signaling in hypertension. This study investigated the vasoactive effect of Up4A in aortas isolated from angiotensin (Ang) II-infused (21 days) hypertensive mice. METHODS Blood pressure was measured by tail cuff plethysmography. Aortas were isolated for isometric tension measurements, and protein expression was analyzed by western blot. RESULTS Mean and systolic arterial pressures were elevated by ~50% in Ang II-infused mice. Protein levels of both AT1R and P2X1R were upregulated in Ang II-infused aortas. Surprisingly, Up4A (10-9-10-5 M)-induced concentration-dependent contraction was significantly impaired in Ang II-infused mice. Studies in control mice revealed that both P2X1R (MRS2159) and AT1R (losartan) antagonists significantly attenuated Up4A-induced aortic contraction. In addition, desensitization of AT1R by prior Ang II (100 nM) exposure had no effect on Up4A-induced aortic contraction. However, subsequent serial exposure responses to Up4A-induced aortic contraction were markedly reduced, suggesting a desensitization of purinergic receptors. This desensitization was further confirmed in control mice by prior exposure of aortas to the P2X1R desensitizer α, β-methylene ATP (10 μM). CONCLUSION Despite upregulation of AT1R and P2X1R in hypertension, Up4A-mediated aortic contraction was impaired in Ang II-infused mice, likely through the desensitization of P2X1R but not AT1R. This implies that vascular P2X1R activity, rather than plasma Up4A level, may determine the role of Up4A in hypertension.
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Affiliation(s)
- Zhichao Zhou
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences, Clinical and Translational Science Institute, West Virginia University, Morgantown, West Virginia, USA
- Present address: Division of Cardiology, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden
| | - Vishal R Yadav
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences, Clinical and Translational Science Institute, West Virginia University, Morgantown, West Virginia, USA
| | - Changyan Sun
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences, Clinical and Translational Science Institute, West Virginia University, Morgantown, West Virginia, USA
- Present address: Molecular Vascular Medicine, Department of Medicine, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden
| | - Bunyen Teng
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences, Clinical and Translational Science Institute, West Virginia University, Morgantown, West Virginia, USA
| | - Jamal S Mustafa
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences, Clinical and Translational Science Institute, West Virginia University, Morgantown, West Virginia, USA
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Kuczeriszka M, Dobrowolski L, Walkowska A, Sadowski J. Influence of P2X receptors on renal medullary circulation is not altered by angiotensin II pretreatment. Pharmacol Rep 2016; 68:1230-1236. [DOI: 10.1016/j.pharep.2016.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/20/2016] [Accepted: 07/29/2016] [Indexed: 12/26/2022]
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12
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Casare FAM, Thieme K, Costa-Pessoa JM, Rossoni LV, Couto GK, Fernandes FB, Casarini DE, Oliveira-Souza M. Renovascular remodeling and renal injury after extended angiotensin II infusion. Am J Physiol Renal Physiol 2016; 310:F1295-307. [PMID: 26962104 DOI: 10.1152/ajprenal.00471.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 03/05/2016] [Indexed: 11/22/2022] Open
Abstract
Chronic angiotensin II (ANG II) infusion for 1 or 2 wk leads to progressive hypertension and induces inward hypertrophic remodeling in preglomerular vessels, which is associated with increased renal vascular resistance (RVR) and decreased glomerular perfusion. Considering the ability of preglomerular vessels to exhibit adaptive responses, the present study was performed to evaluate glomerular perfusion and renal function after 6 wk of ANG II infusion. To address this study, male Wistar rats were submitted to sham surgery (control) or osmotic minipump insertion (ANG II 200 ng·kg(-1)·min(-1), 42 days). A group of animals was treated or cotreated with losartan (10 mg·kg(-1)·day(-1)), an AT1 receptor antagonist, between days 28 and 42 Chronic ANG II infusion increased systolic blood pressure to 185 ± 4 compared with 108 ± 2 mmHg in control rats. Concomitantly, ANG II-induced hypertension increased intrarenal ANG II level and consequently, preglomerular and glomerular injury. Under this condition, ANG II enhanced the total renal plasma flow (RPF), glomerular filtration rate (GFR), urine flow and induced pressure natriuresis. These changes were accompanied by lower RVR and enlargement of the lumen of interlobular arteries and afferent arterioles, consistent with impairment of renal autoregulatory capability and outward preglomerular remodeling. The glomerular injury culminated with podocyte effacement, albuminuria, tubulointerstitial macrophage infiltration and intrarenal extracellular matrix accumulation. Losartan attenuated most of the effects of ANG II. Our findings provide new information regarding the contribution of ANG II infusion over 2 wk to renal hemodynamics and function via the AT1 receptor.
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Affiliation(s)
| | - Karina Thieme
- Laboratory of Cellular and Molecular Endocrinology, Medical School, University of Sao Paulo, Sao Paulo, Brazil; and
| | - Juliana Martins Costa-Pessoa
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Luciana Venturini Rossoni
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Gisele Kruger Couto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | | | - Dulce Elena Casarini
- Division of Nephrology, Department of Medicine, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Maria Oliveira-Souza
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil;
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13
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Abstract
Endothelin (ET) is one of the most potent renal vasoconstrictors. Endothelin plays an essential role in the regulation of renal blood flow, glomerular filtration, sodium and water transport, and acid-base balance. ET-1, ET-2, and ET-3 are the three distinct endothelin isoforms comprising the endothelin family. ET-1 is the major physiologically relevant peptide and exerts its biological activity through two G-protein-coupled receptors: ET(A) and ET(B). Both ET(A) and ET(B) are expressed by the renal vasculature. Although ET(A) are expressed mainly by vascular smooth muscle cells, ET(B) are expressed by both renal endothelial and vascular smooth muscle cells. Activation of the endothelin system, or overexpression of downstream endothelin signaling pathways, has been implicated in several pathophysiological conditions including hypertension, acute kidney injury, diabetic nephropathy, and immune nephritis. In this review, we focus on the effects of endothelin on the renal microvasculature, and update recent findings on endothelin in the regulation of renal hemodynamics.
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Affiliation(s)
- Zhengrong Guan
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Justin P VanBeusecum
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Edward W Inscho
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL.
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14
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Guan Z, Singletary ST, Cha H, Van Beusecum JP, Cook AK, Pollock JS, Pollock DM, Inscho EW. Pentosan polysulfate preserves renal microvascular P2X1 receptor reactivity and autoregulatory behavior in DOCA-salt hypertensive rats. Am J Physiol Renal Physiol 2015; 310:F456-65. [PMID: 26697978 DOI: 10.1152/ajprenal.00110.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 12/21/2015] [Indexed: 01/06/2023] Open
Abstract
Inflammation contributes to ANG II-associated impairment of renal autoregulation and microvascular P2X1 receptor signaling, but its role in renal autoregulation in mineralocorticoid-induced hypertension is unknown. Autoregulatory behavior was assessed using the blood-perfused juxtamedullary nephron preparation. Hypertension was induced in uninephrectomized control rats (UNx) by subcutaneous implantation of a DOCA pellet plus administration of 1% NaCl in the drinking water (DOCA-salt) for 3 wk. DOCA-salt rats developed hypertension that was unaltered by anti-inflammatory treatment with pentosan polysulfate (DOCA-salt+PPS) but was suppressed with "triple therapy" (hydrochlorothiazide, hydralazine, and reserpine; DOCA-salt+TTx). Baseline arteriolar diameters were similar across all groups. UNx rats exhibited pressure-dependent vasoconstriction with diameters declining to 69 ± 2% of control at 170 mmHg, indicating intact autoregulation. DOCA-salt treatment significantly blunted this pressure-mediated vasoconstriction. Diameters remained between 91 ± 4 and 98 ± 3% of control over 65-170 mmHg, indicating impaired autoregulation. In contrast, pressure-mediated vasoconstriction was preserved in DOCA-salt+PPS and DOCA-salt+TTx rats, reaching 77 ± 7 and 75 ± 3% of control at 170 mmHg, respectively. ATP is required for autoregulation via P2X1 receptor activation. ATP- and β,γ-methylene ATP (P2X1 receptor agonist)-mediated vasoconstriction were markedly attenuated in DOCA-salt rats compared with UNx (P < 0.05), but significantly improved by PPS or TTx (P < 0.05 vs. DOCA-salt) treatment. Arteriolar responses to adenosine and UTP (P2Y2 receptor agonist) were unaffected by DOCA-salt treatment. PPS and TTx significantly reduced MCP-1 and protein excretion in DOCA-salt rats. These results support the hypothesis that hypertension triggers inflammatory cascades but anti-inflammatory treatment preserves renal autoregulation in DOCA-salt rats, most likely by normalizing renal microvascular reactivity to P2X1 receptor activation.
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Affiliation(s)
- Zhengrong Guan
- Department of Physiology, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Sean T Singletary
- Department of Physiology, Georgia Regents University, Augusta, Georgia
| | - Haword Cha
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and School of Natural Sciences, University of California, Merced, California
| | - Justin P Van Beusecum
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Anthony K Cook
- Department of Physiology, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Jennifer S Pollock
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - David M Pollock
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Edward W Inscho
- Department of Physiology, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
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15
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Guan Z, Fellner RC, Van Beusecum J, Inscho EW. P2 receptors in renal autoregulation. Curr Vasc Pharmacol 2015; 12:818-28. [PMID: 24066935 DOI: 10.2174/15701611113116660152] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 03/06/2013] [Accepted: 05/01/2014] [Indexed: 11/22/2022]
Abstract
Autoregulation of renal blood flow and glomerular filtration rate is an essential function of the renal microcirculation. While the existence of this phenomenon has been known for many years, the exact mechanisms that underlie this regulatory system remain poorly understood. The work of many investigators has provided insights into many aspects of the autoregulatory mechanism, but many critical components remain elusive. This review is intended to update the reader on the role of P2 purinoceptors as a postulated mechanism responsible for renal autoregulatory resistance adjustments. It will summarize recent advances in normal function and it will touch on more recent ideas regarding autoregulatory insufficiency in hypertension and inflammation. Current thoughts on the nature of the mechanosensor responsible for myogenic behavior will be also be discussed as well as current thoughts on the mechanisms involved in ATP release to the extracellular fluid space.
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Affiliation(s)
| | | | | | - Edward W Inscho
- Department of Physiology, Medical College of Georgia, Georgia Regents University, 1120 15th Street, Augusta, Georgia 30912-3000.
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16
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Fellner RC, Guan Z, Cook AK, Pollock DM, Inscho EW. Endothelin contributes to blunted renal autoregulation observed with a high-salt diet. Am J Physiol Renal Physiol 2015; 309:F687-96. [PMID: 26246513 DOI: 10.1152/ajprenal.00641.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 07/29/2015] [Indexed: 01/03/2023] Open
Abstract
Autoregulation of renal blood flow (RBF) is an essential function of the renal microcirculation that has been previously shown to be blunted by excessive dietary salt. Endogenous endothelin 1 (ET-1) is increased following a high-salt (HS) diet and contributes to the control of RBF but the differential effects of ET-1 on renal microvessel autoregulation in response to HS remain to be established. We hypothesized that a HS diet increases endothelin receptor activation in normal Sprague-Dawley rats and blunts autoregulation of RBF. The role of ET-1 in the blunted autoregulation produced by a HS diet was assessed in vitro and in vivo using the blood-perfused juxtamedullary nephron preparation and anesthetized rats, respectively. Using highly selective antagonists, we observed that blockade of either ETA or ETB receptors was sufficient to restore normal autoregulatory behavior in afferent arterioles from HS-fed rats. Additionally, normal autoregulatory behavior was restored in vivo in HS-fed rats by simultaneous ETA and ETB receptor blockade, whereas blockade of ETB receptors alone showed significant improvement of normal autoregulation of RBF. Consistent with this observation, autoregulation of RBF in ETB receptor-deficient rats fed HS was similar to both ETB-deficient rats and transgenic control rats on normal-salt diets. These data support the hypothesis that endogenous ET-1, working through ETB and possibly ETA receptors, contributes to the blunted renal autoregulatory behavior in rats fed a HS diet.
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Affiliation(s)
- Robert C Fellner
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Zhengrong Guan
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Anthony K Cook
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - David M Pollock
- Section of Experimental Medicine, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; and Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Edward W Inscho
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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17
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Menzies RI, Unwin RJ, Bailey MA. Renal P2 receptors and hypertension. Acta Physiol (Oxf) 2015; 213:232-41. [PMID: 25345692 DOI: 10.1111/apha.12412] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 09/23/2014] [Accepted: 10/17/2014] [Indexed: 12/11/2022]
Abstract
The regulation of extracellular fluid volume is a key component of blood pressure homeostasis. Long-term blood pressure is stabilized by the acute pressure natriuresis response by which changes in renal perfusion pressure evoke corresponding changes in renal sodium excretion. A wealth of experimental evidence suggests that a defect in the pressure natriuresis response contributes to the development and maintenance of hypertension. The mechanisms underlying the relationship between renal perfusion pressure and sodium excretion are incompletely understood. Increased blood flow through the vasa recta increases renal interstitial hydrostatic pressure, thereby reducing the driving force for transepithelial sodium reabsorption. Paracrine signalling also contributes to the overall natriuretic response by inhibiting tubular sodium reabsorption in several nephron segments. In this brief review, we discuss the role of purinergic signalling in the renal control of blood pressure. ATP is released from renal tubule and vascular cells in response to increased flow and can activate P2 receptor subtypes expressed in both epithelial and vascular endothelial/smooth muscle cells. In concert, these effects integrate the vascular and tubular responses to increased perfusion pressure and targeting P2 receptors, particularly P2X7, may prove beneficial for treatment of hypertension.
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Affiliation(s)
- R. I. Menzies
- University/British Heart Foundation; Centre for Cardiovascular Science; The University of Edinburgh; Edinburgh UK
- MRC Institute for Genetics and Molecular Medicine; The University of Edinburgh; Edinburgh UK
| | - R. J. Unwin
- UCL Centre for Nephrology; University College London; London UK
| | - M. A. Bailey
- University/British Heart Foundation; Centre for Cardiovascular Science; The University of Edinburgh; Edinburgh UK
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18
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Polichnowski AJ, Griffin KA, Picken MM, Licea-Vargas H, Long J, Williamson GA, Bidani AK. Hemodynamic basis for the limited renal injury in rats with angiotensin II-induced hypertension. Am J Physiol Renal Physiol 2014; 308:F252-60. [PMID: 25477472 DOI: 10.1152/ajprenal.00596.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ANG II is thought to increase the susceptibility to hypertension-induced renal disease (HIRD) via blood pressure (BP)-dependent and BP-independent pathways; however, the quantitative relationships between BP and HIRD have not been examined in ANG II-infused hypertensive rats. We compared the relationship between radiotelemetrically measured BP and HIRD in Sprague-Dawley rats (Harlan) chronically administered ANG II (300-500 ng·kg(-1)·min(-1), n = 19) for 4 wk versus another commonly employed pharmacological model of hypertension induced by the chronic administration of N(ω)-nitro-l-arginine methyl ester (l-NAME, 50 mg·kg(-1)·day(-1), n = 23). [DOSAGE ERROR CORRECTED]. Despite the significantly higher average systolic BP associated with ANG II (191.1 ± 3.2 mmHg) versus l-NAME (179.9 ± 2.5 mmHg) administration, the level of HIRD was very modest in the ANG II versus l-NAME model as evidenced by significantly less glomerular injury (6.6 ± 1.3% vs. 11.3 ± 1.5%, respectively), tubulointerstitial injury (0.3 ± 0.1 vs. 0.7 ± 0.1 injury score, respectively), proteinuria (66.3 ± 10.0 vs. 117.5 ± 10.1 mg/day, respectively), and serum creatinine levels (0.5 ± 0.04 vs. 0.9 ± 0.07 mg/dl, respectively). Given that HIRD severity is expected to be a function of renal microvascular BP transmission, BP-renal blood flow (RBF) relationships were examined in additional conscious rats administered ANG II (n = 7) or l-NAME (n = 8). Greater renal vasoconstriction was observed during ANG II versus l-NAME administration (41% vs. 23% decrease in RBF from baseline). Moreover, administration of ANG II, but not l-NAME, led to a unique BP-RBF pattern in which the most substantial decreases in RBF were observed during spontaneous increases in BP. We conclude that the hemodynamic effects of ANG II may mediate the strikingly low susceptibility to HIRD in the ANG II-infused model of hypertension in rats.
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Affiliation(s)
- Aaron J Polichnowski
- Hines Veterans Affairs Hospital and Department of Medicine Loyola University, Maywood, Illinois;
| | - Karen A Griffin
- Hines Veterans Affairs Hospital and Department of Medicine Loyola University, Maywood, Illinois
| | - Maria M Picken
- Department of Pathology Loyola University, Maywood, Illinois
| | - Hector Licea-Vargas
- Hines Veterans Affairs Hospital and Department of Medicine Loyola University, Maywood, Illinois
| | - Jianrui Long
- Department of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, Illinois
| | - Geoffrey A Williamson
- Department of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, Illinois
| | - Anil K Bidani
- Hines Veterans Affairs Hospital and Department of Medicine Loyola University, Maywood, Illinois
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19
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Abstract
PURPOSE OF REVIEW The purpose of this review is to provide an update on the current knowledge regarding the role of the intrarenal rennin-angiotensin system (RAS) in the regulation of glomerular function including glomerular dynamics and filtration rate, glomerular permeability and structural alterations during chronic increases in intrarenal angiotensin (Ang) II. RECENT FINDINGS Recent studies have continued to delineate the complex interactions among the various RAS components that participate in regulating glomerular function. Although Ang II acting on AT1 receptors remains as the predominant influence on glomerular dynamics, some of these effects are indirectly mediated by Ang II modulating the sensitivity of the macula densa tubuloglomerular feedback mechanism as well as the more recently described feedback mechanism from the connecting tubule. Interestingly, the actions of Ang II on these systems cause opposite effects on glomerular function demonstrating the complexities associated with the influences of Ang II on glomerular function. When chronically elevated, Ang II also stimulates and/or interacts with other factors, including reactive oxygen species, cytokines and growth factors and other hormones or paracrine agents, to elicit structural alterations. SUMMARY Recent studies have provided further evidence for the presence of many components of the RAS in glomerular structures, which supports the importance of locally produced angiotensin peptides to regulate glomerular haemodynamics, filtration rate and macromolecular permeability and contribute to fibrosis and glomerular injury when inappropriately augmented.
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20
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Fellner RC, Cook AK, O'Connor PM, Zhang S, Pollock DM, Inscho EW. High-salt diet blunts renal autoregulation by a reactive oxygen species-dependent mechanism. Am J Physiol Renal Physiol 2014; 307:F33-40. [PMID: 24872316 DOI: 10.1152/ajprenal.00040.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
High dietary salt is common in Western countries and is an important contributor to increased cardiovascular disease. Autoregulation of renal blood flow (RBF) and glomerular filtration rate (GFR) is an essential function of the renal microcirculation that could be affected by excessive dietary salt. High salt (HS) increases renal ROS generation partly by the enzyme NADPH oxidase. We hypothesized that a HS diet would impair autoregulation via NADPH oxidase-dependent ROS generation. The role of NADPH-dependent ROS production on the blunted autoregulatory response with a HS diet was assessed in vitro and in vivo using the blood-perfused juxtamedullary nephron preparation and anesthetized rats, respectively. The increase in renal lipid peroxidation and p67(phox) expression induced by HS was prevented by apocynin treatment. Control afferent arterioles exhibited normal autoregulatory behavior in response to acute increases in renal perfusion pressure, whereas arterioles from HS rats exhibited a blunted response. Autoregulatory behavior in HS rats was restored in vitro by acute exposure to the NADPH oxidase inhibitor apocynin. At the whole kidney level, in vivo experiments showed that both RBF and GFR declined in HS rats when left kidney renal perfusion pressure was reduced from ambient to 95 mmHg, whereas control rats maintained stable GFR and RBF consistent with efficient autoregulatory behavior. Apocynin treatment improved in vivo autoregulatory behavior in HS rats and had no detectable effect in normal salt diet-fed rats. These data support the hypothesis that impaired renal autoregulatory behavior in rats fed a HS diet is mediated by NADPH oxidase-derived ROS.
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Affiliation(s)
- Robert C Fellner
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; and
| | - Anthony K Cook
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; and
| | - Paul M O'Connor
- Section of Experimental Medicine, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Shali Zhang
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; and
| | - David M Pollock
- Section of Experimental Medicine, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Edward W Inscho
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; and
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21
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Guan Z, Singletary ST, Cook AK, Hobbs JL, Pollock JS, Inscho EW. Sphingosine-1-phosphate evokes unique segment-specific vasoconstriction of the renal microvasculature. J Am Soc Nephrol 2014; 25:1774-85. [PMID: 24578134 DOI: 10.1681/asn.2013060656] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Sphingosine-1-phosphate (S1P), a bioactive sphingolipid metabolite, has been implicated in regulating vascular tone and participating in chronic and acute kidney injury. However, little is known about the role of S1P in the renal microcirculation. Here, we directly assessed the vasoresponsiveness of preglomerular and postglomerular microvascular segments to exogenous S1P using the in vitro blood-perfused juxtamedullary nephron preparation. Superfusion of S1P (0.001-10 μM) evoked concentration-dependent vasoconstriction in preglomerular microvessels, predominantly afferent arterioles. After administration of 10 μM S1P, the diameter of afferent arterioles decreased to 35%±5% of the control diameter, whereas the diameters of interlobular and arcuate arteries declined to 50%±12% and 68%±6% of the control diameter, respectively. Notably, efferent arterioles did not respond to S1P. The S1P receptor agonists FTY720 and FTY720-phosphate and the specific S1P1 receptor agonist SEW2871 each evoked modest afferent arteriolar vasoconstriction. Conversely, S1P2 receptor inhibition with JTE-013 significantly attenuated S1P-mediated afferent arteriolar vasoconstriction. Moreover, blockade of L-type voltage-dependent calcium channels with diltiazem or nifedipine attenuated S1P-mediated vasoconstriction. Intravenous injection of S1P in anesthetized rats reduced renal blood flow dose dependently. Western blotting and immunofluorescence revealed S1P1 and S1P2 receptor expression in isolated preglomerular microvessels and microvascular smooth muscle cells. These data demonstrate that S1P evokes segmentally distinct preglomerular vasoconstriction via activation of S1P1 and/or S1P2 receptors, partially via L-type voltage-dependent calcium channels. Accordingly, S1P may have a novel function in regulating afferent arteriolar resistance under physiologic conditions.
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Affiliation(s)
| | | | | | - Janet L Hobbs
- Experimental Medicine, Georgia Regents University, Augusta, Georgia
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22
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Osmond DA, Zhang S, Pollock JS, Yamamoto T, De Miguel C, Inscho EW. Clopidogrel preserves whole kidney autoregulatory behavior in ANG II-induced hypertension. Am J Physiol Renal Physiol 2014; 306:F619-28. [PMID: 24477682 DOI: 10.1152/ajprenal.00444.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This study tested the hypothesis that P2Y12 receptor blockade with clopidogrel preserves renal autoregulatory ability during ANG II-induced hypertension. Clopidogrel was administered orally to male Sprague-Dawley rats chronically infused with ANG II. After 14 days of treatment, whole kidney autoregulation of renal blood flow was assessed in vivo in pentobarbital-anesthetized rats using an ultrasonic flow probe placed around the left renal artery. In ANG II-vehicle-treated rats, decreasing arterial pressure over a range from 160 to 100 mmHg resulted in a 25 ± 5% decrease in renal blood flow, demonstrating a significant loss of autoregulation with an autoregulatory index of 0.66 ± 0.15. However, clopidogrel treatment preserved autoregulatory behavior in ANG II-treated rats to levels indistinguishable from normotensive sham-operated (sham) rats (autoregulatory index: 0.04 ± 0.14). Compared with normotensive sham-vehicle-treated rats, ANG II infusion increased renal CD3-positive T cell infiltration by 66 ± 6%, induced significant thickening of the preglomerular vessels and glomerular basement membrane and increased glomerular collagen I deposition, tubulointerstitial fibrosis, damage to the proximal tubular brush border, and protein excretion. Clopidogrel significantly reduced renal infiltration of T cells by 39 ± 9% and prevented interstitial artery thickening, ANG II-induced damage to the glomerular basement membrane, deposition of collagen type I, and tubulointerstitial fibrosis, despite the maintenance of hypertension. These data demonstrate that systemic P2Y12 receptor blockade with clopidogrel protects against impairment of autoregulatory behavior and renal vascular injury in ANG II-induced hypertension, possibly by reducing renal T cell infiltration.
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Affiliation(s)
- David A Osmond
- Dept. of Physiology CA-3137, Georgia Regents Univ., 1120 15th St., Augusta, GA 30912.
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23
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Burnstock G, Ralevic V. Purinergic signaling and blood vessels in health and disease. Pharmacol Rev 2013; 66:102-92. [PMID: 24335194 DOI: 10.1124/pr.113.008029] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purinergic signaling plays important roles in control of vascular tone and remodeling. There is dual control of vascular tone by ATP released as a cotransmitter with noradrenaline from perivascular sympathetic nerves to cause vasoconstriction via P2X1 receptors, whereas ATP released from endothelial cells in response to changes in blood flow (producing shear stress) or hypoxia acts on P2X and P2Y receptors on endothelial cells to produce nitric oxide and endothelium-derived hyperpolarizing factor, which dilates vessels. ATP is also released from sensory-motor nerves during antidromic reflex activity to produce relaxation of some blood vessels. In this review, we stress the differences in neural and endothelial factors in purinergic control of different blood vessels. The long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides in promoting migration and proliferation of both vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis and vessel remodeling during restenosis after angioplasty are described. The pathophysiology of blood vessels and therapeutic potential of purinergic agents in diseases, including hypertension, atherosclerosis, ischemia, thrombosis and stroke, diabetes, and migraine, is discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK; and Department of Pharmacology, The University of Melbourne, Australia.
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24
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Palygin O, Levchenko V, Ilatovskaya DV, Pavlov TS, Ryan RP, Cowley AW, Staruschenko A. Real-time electrochemical detection of ATP and H₂O₂ release in freshly isolated kidneys. Am J Physiol Renal Physiol 2013; 305:F134-41. [PMID: 23594827 DOI: 10.1152/ajprenal.00129.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Extracellular nucleotides such as adenosine-5'-triphosphate (ATP) and reactive oxygen species are essential local signaling molecules in the kidney. However, measurements of changes in the interstitial concentrations of these substances in response to various stimuli remain hindered due to limitations of existing experimental techniques. The goal of this study was to develop a novel approach suitable for real-time measurements of ATP and H₂O₂ levels in freshly isolated rat kidney. Rats were anesthetized and the kidneys were flushed to clear blood before isolation for consequent perfusion. The perfused kidneys were placed into a bath solution and dual simultaneous amperometric recordings were made with the enzymatic microelectrode biosensors detecting ATP and H₂O₂. It was found that basal levels of H₂O₂ were increased in Dahl salt-sensitive (SS) rats fed a high-salt diet compared with SS and Sprague-Dawley rats fed a low-salt diet and that medulla contained higher levels of H₂O₂ compared with cortex in both strains. In contrast, ATP levels did not change in SS rats when animals were fed a high-salt diet. Importantly, angiotensin II via AT₁ receptor induced rapid release of both ATP and H₂O₂ and this effect was enhanced in SS rats. These results demonstrate that ATP and H₂O₂ are critical in the development of salt-sensitive hypertension and that the current method represents a unique powerful approach for the real-time monitoring of the changes in endogenous substance levels in whole organs.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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