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Edwards A, Kurtcuoglu V. Renal blood flow and oxygenation. Pflugers Arch 2022; 474:759-770. [PMID: 35438336 PMCID: PMC9338895 DOI: 10.1007/s00424-022-02690-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/19/2022] [Accepted: 03/21/2022] [Indexed: 02/07/2023]
Abstract
Our kidneys receive about one-fifth of the cardiac output at rest and have a low oxygen extraction ratio, but may sustain, under some conditions, hypoxic injuries that might lead to chronic kidney disease. This is due to large regional variations in renal blood flow and oxygenation, which are the prerequisite for some and the consequence of other kidney functions. The concurrent operation of these functions is reliant on a multitude of neuro-hormonal signaling cascades and feedback loops that also include the regulation of renal blood flow and tissue oxygenation. Starting with open questions on regulatory processes and disease mechanisms, we review herein the literature on renal blood flow and oxygenation. We assess the current understanding of renal blood flow regulation, reasons for disparities in oxygen delivery and consumption, and the consequences of disbalance between O2 delivery, consumption, and removal. We further consider methods for measuring and computing blood velocity, flow rate, oxygen partial pressure, and related parameters and point out how limitations of these methods constitute important hurdles in this area of research. We conclude that to obtain an integrated understanding of the relation between renal function and renal blood flow and oxygenation, combined experimental and computational modeling studies will be needed.
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Affiliation(s)
- Aurelie Edwards
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
| | - Vartan Kurtcuoglu
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland. .,National Center of Competence in Research, Kidney.CH, University of Zurich, Zurich, Switzerland. .,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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Franzén S, Näslund E, Wang H, Frithiof R. Prevention of hemorrhage-induced renal vasoconstriction and hypoxia by angiotensin II type 1 receptor antagonism in pigs. Am J Physiol Regul Integr Comp Physiol 2021; 321:R12-R20. [PMID: 34009032 DOI: 10.1152/ajpregu.00073.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Angiotensin II (ANG II) is a potent vasoconstrictor and may reduce renal blood flow (RBF), causing renal hypoxia. Hypotensive hemorrhage elevates plasma ANG II levels and is associated with increased risk of acute kidney injury. We hypothesized that ANG II antagonism prevents renal vasoconstriction and hypoxia caused by hemorrhage. Pigs were anaesthetized, surgically prepared, and randomized to intravenous losartan (1.5 mg·kg-1·h-1, n = 8) or an equal volume of intravenous Ringer acetate (vehicle-treated, n = 8). Hemorrhage was induced by continuous aspiration of blood to reach and sustain mean arterial pressure of <50 mmHg for 30 min. Plasma ANG II levels, hemodynamics and oxygenation were assessed 60 min prehemorrhage, 30-min after the start of hemorrhage, and 60 min posthemorrhage. Erythropoietin mRNA was analyzed in cortical and medullary tissue sampled at the end of the experiment. Hypotensive hemorrhage increased plasma ANG II levels and decreased RBF and oxygen delivery in both groups. Losartan-treated animals recovered in RBF and oxygen delivery, whereas vehicle-treated animals had persistently reduced RBF and oxygen delivery. In accordance, renal vascular resistance increased over time post hemorrhage in vehicle-treated animals but was unchanged in losartan-treated animals. Renal oxygen extraction rate and cortical erythropoietin mRNA levels increased in the vehicle group but not in the losartan group. In conclusion, ANG II antagonism alleviates prolonged renal vasoconstriction and renal hypoxia in a large animal model of hypotensive hemorrhage.
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Affiliation(s)
- Stephanie Franzén
- Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden
| | - Erik Näslund
- Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden.,Centre for Research and Development, Uppsala University/Region Gävleborg, Gavle, Sweden
| | - Helen Wang
- Department of Medical Biochemistry and Microbiology, Infections and Defenses, Uppsala University, Uppsala, Sweden
| | - Robert Frithiof
- Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden
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Further evidence against the role renal medullary perfusion in short-term control of arterial pressure in normotensive and mildly or overtly hypertensive rats. Pflugers Arch 2021; 473:623-631. [PMID: 33651165 PMCID: PMC8049918 DOI: 10.1007/s00424-021-02534-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 12/20/2022]
Abstract
Earlier evidence from studies of rat hypertension models undermines the widespread view that the rate of renal medullary blood flow (MBF) is critical in control of arterial pressure (MAP). Here, we examined the role of MBF in rats that were normotensive, with modest short-lasting pressure elevation, or with overt established hypertension. The groups studied were anaesthetised Sprague-Dawley rats: (1) normotensive, (2) with acute i.v. norepinephrine-induced MAP elevation, and (3) with hypertension induced by unilateral nephrectomy followed by administration of deoxycorticosterone-acetate (DOCA) and 1% NaCl drinking fluid for 3 weeks. MBF was measured (laser-Doppler probe) and selectively increased using 4-h renal medullary infusion of bradykinin. MAP, renal excretion parameters and post-experiment medullary tissue osmolality and sodium concentration were determined. In the three experimental groups, baseline MAP was 117, 151 and 171 mmHg, respectively. Intramedullary bradykinin increased MBF by 45%, 65% and 70%, respectively, but this was not associated with a change in MAP. In normotensive rats a significant decrease in medullary tissue sodium was seen. The intramedullary bradykinin specifically increased renal excretion of water, sodium and total solutes in norepinephrine-treated rats but not in the two other groups. As previously shown in models of rat hypertension, in the normotensive rats and those with acute mild pressure elevation (resembling labile borderline human hypertension), 4-h renal medullary hyperperfusion failed to decrease MAP. Nor did it decrease in DOCA-salt model mimicking low-renin human hypertension. Evidently, within the 4-h observation, medullary perfusion was not a critical determinant of MAP in normotensive and hypertensive rats.
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Sadowski J, Bądzyńska B. Altered renal medullary blood flow: A key factor or a parallel event in control of sodium excretion and blood pressure? Clin Exp Pharmacol Physiol 2020; 47:1323-1332. [PMID: 32163610 DOI: 10.1111/1440-1681.13303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/03/2020] [Accepted: 03/09/2020] [Indexed: 11/29/2022]
Abstract
In the context of the ongoing debate on the mechanism of blood pressure (BP) regulation and pathophysiology of arterial hypertension ("renocentric" vs "neural" concepts), attention is focused on the putative regulatory role of changes in renal medullary blood flow (MBF). Experimental evidence is analysed with regard to the question whether an elevation of BP and renal perfusion pressure (RPP) is likely to increase MBF due to its impaired autoregulation. It is concluded that such increases have been clearly documented only in rats with extracellular fluid volume expansion. A possible translation of this finding to BP regulation in health and hypertension in humans may only be a matter of speculation. Within the "renocentric" theory, the key event leading to restoration of initial BP level is pressure natriuresis. Its relation to elevation of renal interstitial hydrostatic pressure and to the phenomenon of "wash-out" of renal medullary solutes by increasing MBF is discussed. We also assessed the validity of data supporting the putative mechanism of short-term restoration of elevated BP owing to the release of a vasodilator lipid (medullipin) by the medulla. The structure of the proposed medullary lipid is still undefined, and there is no sound evidence on its mediatory role in lowering elevated BP level. In conclusion, MBF change can hardly be regarded as a crucial event in the regulation of BP: it can be involved in the control of sodium excretion and BP only in some circumstances, although its contributory role cannot be excluded.
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Affiliation(s)
- Janusz Sadowski
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Bożena Bądzyńska
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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Ramchandra R, Xing DT, Matear M, Lambert G, Allen AM, May CN. Neurohumoral interactions contributing to renal vasoconstriction and decreased renal blood flow in heart failure. Am J Physiol Regul Integr Comp Physiol 2019; 317:R386-R396. [DOI: 10.1152/ajpregu.00026.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In heart failure (HF), increases in renal sympathetic nerve activity (RSNA), renal norepinephrine spillover, and renin release cause renal vasoconstriction, which may contribute to the cardiorenal syndrome. To increase our understanding of the mechanisms causing renal vasoconstriction in HF, we investigated the interactions between the increased activity of the renal nerves and the renal release of norepinephrine and renin in an ovine pacing-induced model of HF compared with healthy sheep. In addition, we determined the level of renal angiotensin type-1 receptors and the renal vascular responsiveness to stimulation of the renal nerves and α1-adrenoceptors. In conscious sheep with mild HF (ejection fraction 35%–40%), renal blood flow (276 ± 13 to 185 ± 18 mL/min) and renal vascular conductance (3.8 ± 0.2 to 3.1 ± 0.2 mL·min−1·mmHg−1) were decreased compared with healthy sheep. There were increases in the burst frequency of RSNA (27%), renal norepinephrine spillover (377%), and plasma renin activity (141%), whereas the density of renal medullary angiotensin type-1 receptors decreased. In anesthetized sheep with HF, the renal vasoconstrictor responses to electrical stimulation of the renal nerves or to phenylephrine were attenuated. Irbesartan improved the responses to nerve stimulation, but not to phenylephrine, in HF and reduced the responses in normal sheep. In summary, in HF, the increases in renal norepinephrine spillover and plasma renin activity are augmented compared with the increase in RSNA. The vasoconstrictor effect of the increased renal norepinephrine and angiotensin II is offset by reduced levels of renal angiotensin type-1 receptors and reduced renal vasoconstrictor responsiveness to α1-adrenoceptor stimulation.
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Affiliation(s)
- Rohit Ramchandra
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Daniel T. Xing
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Marcus Matear
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
- Department of Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Gavin Lambert
- Iverson Health Innovation Research Institute and Faculty of Health, Arts and Design, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Andrew M. Allen
- Department of Physiology, University of Melbourne, Parkville, VIC, Australia
| | - Clive N. May
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
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Angiotensin II receptor blockers following intravenous nicardipine administration to lower blood pressure in patients with hypertensive intracerebral hemorrhage: a prospective randomized study. Blood Press Monit 2017; 22:34-39. [PMID: 27824680 DOI: 10.1097/mbp.0000000000000225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND OBJECTIVE In patients with hypertensive intracerebral hemorrhage (HICH), intravenous nicardipine is primarily used to lower blood pressure (BP). However, there are few studies investigating the role of oral antihypertensives administered after intravenous nicardipine to prevent BP from rising. Angiotensin II receptor blockers (ARBs) may be beneficial in HICH patients not only as antihypertensives but also by lowering plasma catecholamine levels. A prospective randomized study was conducted between January 2015 and March 2016 to comparatively evaluate the efficacy of two ARBs (azilsartan vs. candesartan) following intravenous nicardipine administration on BP reduction. PATIENTS AND METHODS Thirty conscious HICH patients presenting within 6 h of symptom onset were enrolled (15 in each arm). After administering intravenous nicardipine for 24-48 h, the patients were randomized either to the azilsartan (20 mg) arm or to the candesartan (8 mg) arm. Frequency of hematoma expansion, 30-day modified Rankin scale, and temporal profiles of systolic blood pressure (SBP) and plasma norepinephrine/aldosterone were compared. RESULTS Substantial hematoma expansion occurred in two (13%) azilsartan patients and in one (7%) candesartan patient (P=1.00). SBPs were maintained at lower than 140±20 mmHg in both arms. Neither SBPs nor plasma norepinephrine/aldosterone levels differed significantly. All 30 patients had 30-day modified Rankin scale scores of 1-2. CONCLUSION Administration of ARBs following intravenous nicardipine effectively prevented BP from rising in HICH patients. However, whether BP should be strictly managed after 24 h of symptom onset should be addressed in future studies focusing not only on neurologic but also on cardiovascular and renal functions of HICH patients.
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Stock E, Vanderperren K, Bosmans T, Dobbeleir A, Duchateau L, Hesta M, Lybaert L, Peremans K, Vandermeulen E, Saunders J. Evaluation of Feline Renal Perfusion with Contrast-Enhanced Ultrasonography and Scintigraphy. PLoS One 2016; 11:e0164488. [PMID: 27736928 PMCID: PMC5063434 DOI: 10.1371/journal.pone.0164488] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/26/2016] [Indexed: 01/27/2023] Open
Abstract
Contrast-enhanced ultrasound (CEUS) is an emerging technique to evaluate tissue perfusion. Promising results have been obtained in the evaluation of renal perfusion in health and disease, both in human and veterinary medicine. Renal scintigraphy using 99mTc-Mercaptoacetyltriglycine (MAG3) is another non-invasive technique that can be used to evaluate renal perfusion. However, no data are available on the ability of CEUS or 99mTc- MAG3 scintigraphy to detect small changes in renal perfusion in cats. Therefore, both techniques were applied in a normal feline population to evaluate detection possibilities of perfusion changes by angiotensin II (AT II). Contrast-enhanced ultrasound using a bolus injection of commercially available contrast agent and renal scintigraphy using 99mTc-MAG3 were performed in 11 healthy cats after infusion of 0,9% NaCl (control) and AT II. Angiotensin II induced changes were noticed on several CEUS parameters. Mean peak enhancement, wash-in perfusion index and wash-out rate for the entire kidney decreased significantly after AT II infusion. Moreover, a tendency towards a lower wash-in area-under-the curve was present. Renal scintigraphy could not detect perfusion changes induced by AT II. This study shows that CEUS is able to detect changes in feline renal perfusion induced by AT II infusion.
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Affiliation(s)
- Emmelie Stock
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
- * E-mail:
| | - Katrien Vanderperren
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Tim Bosmans
- Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - André Dobbeleir
- Ghent University Hospital, Department of Radiology and Nuclear Medicine, De Pintelaan 185, 9000 Ghent, Belgium
| | - Luc Duchateau
- Department of Comparative Physiology and Biometry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Myriam Hesta
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Lien Lybaert
- Lab of Pharmaceutical technology, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, Ghent, Belgium
| | - Kathelijne Peremans
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Eva Vandermeulen
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Jimmy Saunders
- Department of Medical Imaging of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
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Cortical and Medullary Tissue Perfusion and Oxygenation in Experimental Septic Acute Kidney Injury. Crit Care Med 2015; 43:e431-9. [PMID: 26181218 DOI: 10.1097/ccm.0000000000001198] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine whether there is a decrease in renal cortical or medullary perfusion and oxygenation in a conscious large animal model of hyperdynamic septic shock with acute kidney injury. DESIGN Interventional animal study. SETTING University-affiliated research institute. SUBJECTS Eight merino ewes. INTERVENTIONS Sheep were surgically instrumented with pulmonary and renal artery flow probes in the renal cortex and medulla, combination fiber-optic probes comprising a fluorescence optode to measure tissue PO2, and a laser-Doppler probe to assess tissue perfusion. Sepsis was induced by infusion of live Escherichia coli for 24 hours followed by 24-hour recovery. MEASUREMENTS AND MAIN RESULTS In unanesthetized normal sheep, resting levels of cortical and medullary tissue PO2 were 29.5 ± 4.4 and 29.1 ± 4.3 mm Hg, respectively. During infusion of E. coli, hyperdynamic sepsis developed with hypotension, tachycardia, increased cardiac output, increased renal blood flow, oliguria, decreased creatinine clearance, and increased serum creatinine. Renal oxygen delivery increased while renal oxygen consumption was unchanged. During sepsis, cortical tissue PO2 increased from 29.4 ± 4.3 to 36.3 ± 3.5 mm Hg (p < 0.001), whereas medullary oxygenation decreased from 29.6 ± 4.7 to 13.1 ± 2.7 mm Hg (p < 0.001). Cortical perfusion was not significantly changed, but medullary perfusion decreased (671 BPU [500-900 BPU] to 480 BPU [349-661 BPU]; geometric mean [95% CI]; p < 0.001). CONCLUSIONS In a large animal model of hyperdynamic sepsis, renal hyperemia was associated with preserved cortical oxygenation and perfusion, but decreased medullary oxygenation and perfusion. Medullary hypoxia due to intrarenal blood flow redistribution may be one of the factors causing acute kidney injury in sepsis.
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Das S, Mattson DL. Exogenous L-arginine attenuates the effects of angiotensin II on renal hemodynamics and the pressure natriuresis-diuresis relationship. Clin Exp Pharmacol Physiol 2014; 41:270-8. [PMID: 24472006 DOI: 10.1111/1440-1681.12212] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/22/2013] [Accepted: 12/14/2013] [Indexed: 02/05/2023]
Abstract
Administration of exogenous L-arginine (L-Arg) attenuates angiotensin-II (AngII)-mediated hypertension and kidney disease in rats. The present study assessed renal hemodynamics and pressure diuresis-natriuresis in anaesthetized rats infused with vehicle, AngII (20 ng/kg per min i.v.) or AngII + L-Arg (300 μg/kg per min i.v.). Experiments in isolated aortic rings were carried out to assess L-Arg effects on the vasculature. Increasing renal perfusion pressure (RPP) from ~100 to 140 mmHg resulted in a nine- to tenfold increase in urine flow and sodium excretion rate in control animals. In comparison, AngII infusion significantly reduced renal blood flow (RBF) and glomerular filtration rate (GFR) by 40-42%, and blunted the pressure-dependent increase in urine flow and sodium excretion rate by 54-58% at elevated RPP. Supplementation of L-Arg reversed the vasoconstrictor effects of AngII and restored pressure-dependent diuresis to levels not significantly different from control rats. Dose-dependent contraction to AngII (10(-10) mol/L to 10(-7) mol/L) was observed with a maximal force equal to 27 ± 3% of the response to 10(-5) mol/L phenylephrine. Contraction to 10(-7) mol/L AngII was blunted by 75 ± 3% with 10(-4) mol/L L-Arg. The influence of L-Arg to blunt AngII-mediated contraction was eliminated by endothelial denudation or incubation with nitric oxide synthase inhibitors. Furthermore, the addition of 10(-3) mol/L cationic or neutral amino acids, which compete with L-Arg for cellular uptake, blocked the effect of L-Arg. Anionic amino acids did not influence the effects of L-Arg on AngII-mediated contraction. These studies show that L-Arg blunts AngII-mediated vascular contraction by an endothelial- and nitric oxide synthase-dependent mechanism involving cellular uptake of L-Arg.
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Affiliation(s)
- Satarupa Das
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Metoprolol restores expression and vasodilatation function of AT2R in spontaneously hypertensive rats. J Cardiovasc Pharmacol 2014; 63:252-8. [PMID: 24193197 DOI: 10.1097/fjc.0000000000000042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Angiotensin II type 2 receptor (AT2R) is thought as an important regulatory target during antihypertensive treatment but its role in vasomotor regulation remains controversial. The interactional relationship between the sympathetic nervous systems and the renin-angiotensin-aldosterone system (RAS) has been revealed but poorly investigated. This work was designed to explore the effect of metoprolol (MET) treatment on the RAS, especially the expression and vasomotor function of AT2R, in spontaneously hypertensive rats (SHR). The results showed that upregulated renin activity and Ang II concentration of plasma in SHR were inhibited by MET treatment. In isolated superior mesenteric arteries from both Wistar-Kyoto rats and SHR, Ang II perfusion induced vasodilatation after AT1R inhibition by telmisartan, although the vasodilatation was harmed in SHR. Furthermore, AT2R inhibitor PD123319 arrested the vasodilatation induced by Ang II. SHR received MET exerted improved vasodilatation mediated by AT2R (47.29% ± 5.16% vs. 24.99% ± 4.93% for MET and SHR, respectively; P < 0.05). Western blot analysis showed that MET restored expression of AT2R in SHR, which may contribute to MET's antihypertensive effect. These results suggested an impact of β-adrenergic blocker on RAS and supported an important role of AT2R in antihypertensive treatment.
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Ramesh S, Wilton SB, Holroyd-Leduc JM, Turin TC, Sola DY, Ahmed SB. Testosterone is associated with the cardiovascular autonomic response to a stressor in healthy men. Clin Exp Hypertens 2014; 37:184-91. [DOI: 10.3109/10641963.2014.933966] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Sharanya Ramesh
- Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada,
- Libin Cardiovascular Institute of Alberta, Calgary, Alberta, Canada, and
| | - Stephen B. Wilton
- Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada,
- Libin Cardiovascular Institute of Alberta, Calgary, Alberta, Canada, and
| | | | - Tanvir C. Turin
- Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada,
| | - Darlene Y. Sola
- Libin Cardiovascular Institute of Alberta, Calgary, Alberta, Canada, and
| | - Sofia B. Ahmed
- Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada,
- Libin Cardiovascular Institute of Alberta, Calgary, Alberta, Canada, and
- Alberta Kidney Disease Network, Alberta, Canada
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Bądzyńska B, Lipkowski AW, Sadowski J, Kompanowska-Jezierska E. Vascular effects of a tripeptide fragment of novokinine in hypertensive rats: Mechanism of the hypotensive action. Pharmacol Rep 2014; 66:856-61. [PMID: 25149991 DOI: 10.1016/j.pharep.2014.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 04/04/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Activation of angiotensin AT2 receptors (AT2R) counteracts vasoconstrictor effects of AT1R stimulation and contributes to blood pressure control. We examined effects on mean arterial pressure (MAP) and renal hemodynamics of LKP, a tripeptide fragment of novokinine, an established AT2R agonist. METHODS Effects of intravenous LKP infusion and then superimposed losartan (AT1R antagonist) on MAP, total renal (RBF, Transonic probe) and renal medullary blood flows (laser-Doppler), and on renal excretion, were examined in anesthetized (1) Wistar rats with acute norepinephrine-induced hypertension, untreated or pretreated with AT2R antagonist (PD 123319) and (2) spontaneously hypertensive rats (SHR) maintained on standard or high-sodium (HS) diet. RESULTS In Wistar rats LKP decreased MAP (-4%, p<0.01) and increased renal medullary perfusion, these effects were abolished in rats pretreated with PD 123319 in which a post-LKP increase in MAP (+6%, p<0.02) occurred. LKP did not alter MAP in SHR; in those on HS diet RBF decreased (-14%, p<0.02), the response that was reverted by losartan. Addition of losartan always decreased or tended to decrease MAP. CONCLUSIONS LKP lowered MAP in norepinephrine-induced hypertension, probably via activation of AT2R. At reduced availability of AT2R, as in SHR, LKP appeared to bind to different receptors, possibly AT1, and induced systemic or renal vasoconstriction. Compared to the parent novokinine, a smaller LKP molecule might be easier absorbed after oral application and more useful in therapy.
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Affiliation(s)
- Bożena Bądzyńska
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Reasearch Center Polish Academy of Sciences, Warszawa, Poland.
| | - Andrzej W Lipkowski
- Department of Neuropeptides, Mossakowski Medical Reasearch Center Polish Academy of Sciences, Warszawa, Poland
| | - Janusz Sadowski
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Reasearch Center Polish Academy of Sciences, Warszawa, Poland
| | - Elżbieta Kompanowska-Jezierska
- Department of Renal and Body Fluid Physiology, Mossakowski Medical Reasearch Center Polish Academy of Sciences, Warszawa, Poland
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Konstantinidis G, Head GA, Evans RG, Nguyen-Huu TP, Venardos K, Croft KD, Mori TA, Kaye DM, Rajapakse NW. Endothelial cationic amino acid transporter-1 overexpression can prevent oxidative stress and increases in arterial pressure in response to superoxide dismutase inhibition in mice. Acta Physiol (Oxf) 2014; 210:845-53. [PMID: 24428817 DOI: 10.1111/apha.12215] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/30/2013] [Accepted: 12/11/2013] [Indexed: 12/28/2022]
Abstract
AIM Oxidative stress may play an important role in the pathogenesis of hypertension. The aim of our study is to examine whether increased expression of the predominant endothelial l-arginine transporter, cationic amino acid transporter-1 (CAT1), can prevent oxidative stress-induced hypertension. METHODS Wild-type mice (WT; n = 9) and endothelial CAT1 overexpressing (CAT+) mice (n = 6) had telemetry probes implanted for the measurement of mean arterial pressure (MAP), heart rate (HR) and locomotor activity. Minipumps were implanted for infusion of the superoxide dismutase inhibitor diethyldithiocarbamic acid (DETCA; 30 mg kg(-1) day(-1) ; 14 days) or its saline vehicle. Baseline levels of MAP, HR and locomotor activity were determined before and during chronic DETCA administration. Mice were then killed, and their plasma and kidneys collected for analysis of F2 -isoprostane levels. RESULTS Basal MAP was less in CAT+ (92 ± 2 mmHg; n = 6) than in WT (98 ± 2 mmHg; n = 9; P < 0.001). During DETCA infusion, MAP was increased in WT (by 4.2 ± 0.5%; P < 0.001) but not in CAT+, when compared to appropriate controls (PDETCA*genotype = 0.006). DETCA infusion increased total plasma F2 -isoprostane levels (by 67 ± 11%; P = 0.05) in WT but not in CAT+. Total renal F2 -isoprostane levels were greater during DETCA infusion in WT (by 72%; P < 0.001), but not in CAT+, compared to appropriate controls. CONCLUSION Augmented endothelial l-arginine transport attenuated the prohypertensive effects of systemic and renal oxidative stress, suggesting that manipulation of endothelial CAT1 may provide a new therapeutic approach for the treatment of cardiovascular disease associated with oxidative stress.
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Affiliation(s)
- G. Konstantinidis
- Baker IDI Heart and Diabetes Institute; Melbourne Vic. Australia
- Department of Physiology; Monash University; Melbourne Vic. Australia
| | - G. A. Head
- Baker IDI Heart and Diabetes Institute; Melbourne Vic. Australia
| | - R. G. Evans
- Department of Physiology; Monash University; Melbourne Vic. Australia
| | - T.-P. Nguyen-Huu
- Baker IDI Heart and Diabetes Institute; Melbourne Vic. Australia
| | - K. Venardos
- Baker IDI Heart and Diabetes Institute; Melbourne Vic. Australia
| | - K. D. Croft
- School of Medicine and Pharmacology; Royal Perth Hospital Unit; University of Western Australia; Perth WA Australia
| | - T. A. Mori
- School of Medicine and Pharmacology; Royal Perth Hospital Unit; University of Western Australia; Perth WA Australia
| | - D. M. Kaye
- Baker IDI Heart and Diabetes Institute; Melbourne Vic. Australia
| | - N. W. Rajapakse
- Baker IDI Heart and Diabetes Institute; Melbourne Vic. Australia
- Department of Physiology; Monash University; Melbourne Vic. Australia
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14
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Dietrich A, Mathia S, Kaminski H, Mutig K, Rosenberger C, Mrowka R, Bachmann S, Paliege A. Chronic activation of vasopressin V2 receptor signalling lowers renal medullary oxygen levels in rats. Acta Physiol (Oxf) 2013; 207:721-31. [PMID: 23347696 DOI: 10.1111/apha.12067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/27/2012] [Accepted: 01/17/2013] [Indexed: 12/17/2022]
Abstract
AIM In the present study, we aimed to elucidate the effects of chronic vasopressin administration on renal medullary oxygen levels. METHODS Adult Sprague Dawley or vasopressin-deficient Brattleboro rats were treated with the vasopressin V2 receptor agonist, desmopressin (5 ng/h; 3d), or its vehicle via osmotic minipumps. Immunostaining for pimonidazole and the transcription factor HIF-1α (hypoxia-inducible factor-1α) were used to identify hypoxic areas. Activation of HIF-target gene expression following desmopressin treatment was studied by microarray analysis. RESULTS Pimonidazole staining was detected in the outer and inner medulla of desmopressin-treated rats, whereas staining in control animals was weak or absent. HIF-1α immunostaining demonstrated nuclear accumulation in the papilla of desmopressin-treated animals, whereas no staining was observed in the controls. Gene expression analysis revealed significant enrichment of HIF-target genes in the group of desmopressin-regulated gene products (P = 2.6*10(-21) ). Regulated products included insulin-like growth factor binding proteins 1 and 3, angiopoietin 2, fibronectin, cathepsin D, hexokinase 2 and cyclooxygenase 2. CONCLUSION Our results demonstrate that an activation of the renal urine concentrating mechanism by desmopressin causes renal medullary hypoxia and an upregulation of hypoxia-inducible gene expression.
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Affiliation(s)
- A. Dietrich
- Department of Anatomy; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - S. Mathia
- Department of Nephrology; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - H. Kaminski
- Department of Anatomy; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - K. Mutig
- Department of Anatomy; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - C. Rosenberger
- Department of Nephrology; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - R. Mrowka
- Experimentelle Nephrologie; KIM III; Universitästsklinikum Jena; Jena; Germany
| | - S. Bachmann
- Department of Anatomy; Charité-Universitätsmedizin Berlin; Berlin; Germany
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15
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Marvar PJ, Harrison DG. Stress-dependent hypertension and the role of T lymphocytes. Exp Physiol 2012; 97:1161-7. [PMID: 22941978 DOI: 10.1113/expphysiol.2011.061507] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hypertension is a significant global health burden that is associated with an increased risk of stroke, atherosclerosis and other cardiovascular diseases. Several risk factors, including high dietary salt, obesity, genetics and race, as well as behavioural and psychological factors, contribute to development of this complex disease. Various hypertensive stimuli enhance sympathetic drive and promote autonomic dysfunction leading to elevated blood pressure. As our understanding of the pathogenesis and end-organ damage associated with hypertension increases, mounting evidence also highlights the role of inflammation in this process and, in particular, the role of the adaptive immune system and T cells. This review discusses recent findings regarding the role of the central nervous system, T lymphocytes and the impact of cardiovascular risk factors, such as psychological stress, in hypertension.
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Affiliation(s)
- Paul J Marvar
- Department of Psychiatry, Emory University School of Medicine, Atlanta, GA, USA.
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16
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Marvar PJ, Vinh A, Thabet S, Lob HE, Geem D, Ressler KJ, Harrison DG. T lymphocytes and vascular inflammation contribute to stress-dependent hypertension. Biol Psychiatry 2012; 71:774-82. [PMID: 22361077 PMCID: PMC3354001 DOI: 10.1016/j.biopsych.2012.01.017] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 12/20/2011] [Accepted: 01/13/2012] [Indexed: 02/07/2023]
Abstract
BACKGROUND Psychological stress is a significant risk factor for hypertension and also directly affects the immune system. We have previously reported that T lymphocytes are essential for development of hypertension and that the central nervous system contributes to peripheral T-lymphocyte activation and vascular inflammation in this disease; however, the role of T-cell activation in stress-related hypertension remains unclear. METHODS Wild-type and T-cell-deficient (RAG-1(-/-)) mice were subjected to daily episodes of stress and blood pressure was measured. Circulating T-cell activation markers and vascular infiltration of immune cells were analyzed, as were stress hormone levels and gene expression changes in the brain. The effects angiotensin II infusion in the presence of chronic stress was also studied. RESULTS Repeated daily stress contributed to acute elevations in blood pressure that were associated with increased activation of circulating T cells and increased vascular infiltration of T cells. Repeated stress increased blood pressure in wild-type but not RAG-1(-/-) mice. Adoptive transfer of T cells to RAG-1(-/-) mice restored blood pressure elevation in response to stress. Stress-related hypertension and vascular infiltration of T cells was markedly enhanced by angiotensin II. Moreover, angiotensin II-infused mice exposed to chronic stress exhibited greater blood pressure reactivity to an episode of acute stress. CONCLUSIONS These data demonstrate that stress-dependent hypertension triggers an inflammatory response that raises blood pressure at baseline and augments the hypertension caused by angiotensin II. These data provide insight as to how psychological stress contributes to hypertension.
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Affiliation(s)
- Paul J. Marvar
- Emory University School of Medicine Department of Psychiatry and the Center of Behavioral Sciences
| | - Antony Vinh
- Department of Pharmacology Monash University
| | - Salim Thabet
- Division of Clinical Pharmacology and Department of Medicine, Vanderbilt University School of Medicine
| | | | - Duke Geem
- Emory University Department of Pediatrics
| | - Kerry J. Ressler
- Emory University School of Medicine Department of Psychiatry and the Center of Behavioral Sciences,Howard Hughes Medical Institute
| | - David G. Harrison
- Division of Clinical Pharmacology and Department of Medicine, Vanderbilt University School of Medicine
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17
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Ahmeda AF, Johns EJ. The regulation of blood perfusion in the renal cortex and medulla by reactive oxygen species and nitric oxide in the anaesthetised rat. Acta Physiol (Oxf) 2012; 204:443-50. [PMID: 21827636 DOI: 10.1111/j.1748-1716.2011.02346.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS The regulation of blood flow through the renal medulla is important in determining blood pressure, and its dysregulation in pathophysiological states, such as oxidative stress, may contribute to the development of hypertension. This investigation examined the hypothesis that reactive oxygen species has both direct and indirect actions, via scavenging NO, to determine the degree of blood perfusion through the renal medulla. METHODS Groups of male Wistar rats received a renal interstitial infusion of either tempol, a superoxide dismutase (SOD) mimetic, or tempol plus catalase (tem + cat), or diethyldithio-carbamic acid (DETC) a SOD inhibitor, or L-NAME alone or L-NAME followed by DETC. RESULTS Medullary blood perfusion (MBP) increased by 16 ± 1% (P < 0.05) following the renal infusion of tempol and by 35 ± 4%% (P < 0.05) when tem + cat was infused. Cortical blood perfusion (CBP) was unchanged during the administration of tempol and tem + cat. The renal interstitial infusion of DETC reduced CBP by 13 ± 2%, (P < 0.05) and MBP by 22 ± 3% (P < 0.05). Infusion of L-NAME to block NOS did not change CBP but decreased MBP by 12 ± 4%, which was (P < 0.05) less than the reduction obtained with DETC. Administration of DETC in the presence of L-NAME reduced CBP and MBP by 17 and 14%, respectively, the latter response being approximately half that obtained when only DETC was infused. CONCLUSIONS These findings demonstrated that both reactive oxygen species and NO determined the level of MBP. The findings support the hypothesis that reactive oxygen species can act both indirectly, via scavenging of NO, and directly via H(2)O(2) to modulate blood perfusion in the medulla.
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Affiliation(s)
- A F Ahmeda
- Department of Physiology, University College Cork, Ireland
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18
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Eppel GA, Head GA, Denton KM, Evans RG. Effects of tempol and candesartan on neural control of the kidney. Auton Neurosci 2012; 168:48-57. [PMID: 22336580 DOI: 10.1016/j.autneu.2012.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 01/21/2012] [Accepted: 01/22/2012] [Indexed: 02/07/2023]
Abstract
We compared the effects of tempol (300 μmol kg(-1) plus 300 μmol kg(-1) h(-1), n=14) and candesartan (10 μg kg(-1) plus 10 μg kg(-1) h(-1), n=14) on renal haemodynamics, excretory function, and responses to electrical stimulation of the renal nerves (RNS) in lean and obese rabbits under pentobarbitone anaesthesia. Depressor responses to tempol (-16 ± 2 mmHg) and candesartan (-12 ± 1 mmHg) were similar. Candesartan, but not tempol, significantly increased basal renal blood flow (RBF; +36 ± 7%). Tempol, but not candesartan, significantly reduced glomerular filtration rate (GFR; -30 ± 10%) and sodium excretion (U(Na)V; -44 ± 14%). RNS induced frequency-dependent reductions in RBF (-20 ± 3% at 1 Hz), GFR (-28 ± 6% at 1 Hz) and U(Na)V (-55 ± 6% at 1 Hz). Candesartan blunted these responses. Tempol did not significantly alter RBF and GFR responses to RNS but blunted the U(Na)V response. Responses to RNS, and the effects of tempol and candesartan, were similar in lean compared with obese rabbits. Unlike candesartan, tempol did not induce renal vasodilatation, maintain GFR and U(Na)V during reductions in arterial pressure, or blunt neurally-mediated vasoconstriction. In conclusion, unlike the AT(1)-receptor antagonist candesartan, tempol does not blunt the effects of RNS on renal haemodynamic function. Furthermore, under the current experimental conditions superoxide appears to make little contribution to the actions of endogenous angiotensin II on baseline renal haemodynamics or excretory function, or their responses to RNS.
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Affiliation(s)
- Gabriela A Eppel
- Department of Physiology, Monash University, Melbourne, Australia
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20
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Rajapakse NW, Mattson DL. Role of L-arginine uptake mechanisms in renal blood flow responses to angiotensin II in rats. Acta Physiol (Oxf) 2011; 203:391-400. [PMID: 21649863 DOI: 10.1111/j.1748-1716.2011.02330.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
AIM To examine whether reduced renal arginine transport increases the responsiveness of the renal circulation to angiotensin II in salt sensitivity, renal perfusion responses to angiotensin II were examined in the presence of L-arginine transport inhibitor, L-lysine and subsequent L-arginine in Sprague Dawley (SD) and Dahl salt-sensitive (Dahl S) rats. METHODS Laser Doppler probes and a transonic flow probe were used to measure regional renal perfusion and total renal perfusion respectively. Renal perfusion responses to intravenous (i.v.) angiotensin II were sequentially examined under control conditions and during i.v. infusion of L-lysine, L-arginine or nitric oxide synthase inhibitor, N(G)-nitro-L-arginine. RESULTS Angiotensin II (10 and 100 ng kg(-1) min(-1) , i.v.) reduced total renal (-10 ± 3 and -36 ± 5%) and cortical (-10 ± 2 and -28 ± 4%) but not medullary perfusion in SD rats. In these rats L-lysine enhanced the renal perfusion response (P = 0.003), whereas subsequent L-arginine reversed this effect (P = 0.04). Angiotensin II reduced total renal, cortical and medullary perfusion in Dahl S rats. In Dahl S rats fed high salt, L-lysine did not affect renal perfusion responses to angiotensin II, but subsequent L-arginine blunted the renal blood flow response (P = 0.01) and increased the medullary perfusion during angiotensin II infusion (P = 0.006). CONCLUSION Intact renal L-arginine transport attenuates the vasoconstrictor effects of circulating angiotensin II in the renal cortex in SD rats. L-arginine also plays an important role in protecting the renal medullary circulation from the ischemic effects of angiotensin II in Dahl S rats.
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Affiliation(s)
- N W Rajapakse
- Department of Physiology, Medical College of Wisconsin, Milwaukee, USA.
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21
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Evans RG, Goddard D, Eppel GA, O'Connor PM. Stability of tissue PO2 in the face of altered perfusion: a phenomenon specific to the renal cortex and independent of resting renal oxygen consumption. Clin Exp Pharmacol Physiol 2011; 38:247-54. [PMID: 21306412 DOI: 10.1111/j.1440-1681.2011.05494.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
1. Oxygen tension (PO(2)) in renal cortical tissue can remain relatively constant when renal blood flow changes in the physiological range, even when changes in renal oxygen delivery (DO(2)) and oxygen consumption (VO(2)) are mismatched. In the current study, we examined whether this also occurs in the renal medulla and skeletal muscle, or if it is an unusual property of the renal cortex. We also examined the potential for dysfunction of the mechanisms underlying this phenomenon to contribute to kidney hypoxia in disease states associated with increased renal VO(2) . 2. In both the kidney and hindlimb of pentobarbitone anaesthetized rabbits, whole organ blood flow was reduced by intra-arterial infusion of angiotensin-II and increased by acetylcholine infusion. In the kidney, this was carried out before and during renal arterial infusion of the mitochondrial uncoupler, 2,4-dinitrophenol (DNP), or its vehicle. 3. Angiotensin-II reduced renal (-34%) and hindlimb (-25%) DO(2) , whereas acetylcholine increased renal (+38%) and hindlimb (+66%) DO(2) . However, neither renal nor hindlimb VO(2) were altered. Tissue PO(2) varied with local perfusion in the renal medulla and biceps femoris, but not the renal cortex. DNP increased renal VO(2) (+38%) and reduced cortical tissue PO(2) (-44%), but both still remained stable during subsequent infusion of angiotensin-II and acetylcholine. 4. We conclude that maintenance of tissue PO(2) in the face of mismatched changes in local perfusion and VO(2) is an unusual property of the renal cortex. The underlying mechanisms remain unknown, but our current findings suggest they are not compromised when resting renal VO(2) is increased.
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Affiliation(s)
- Roger G Evans
- Department of Physiology, Monash University, Melbourne, Victoria, Australia.
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22
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Badzyńska B, Sadowski J. Moderate intrarenal vasoconstriction after high pressor doses of norepinephrine in the rat: comparison with effects of angiotensin II. Kidney Blood Press Res 2011; 34:307-10. [PMID: 21606652 DOI: 10.1159/000328328] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 04/02/2011] [Indexed: 02/02/2023] Open
Abstract
AIMS Treatment of arterial hypotension with norepinephrine (NE) is associated with renal vasoconstriction and may lead to ischemic kidney injury; the risk involved is still a matter of debate. METHODS In anesthetized, acutely uninephrectomized rats, we examined changes in intrarenal hemodynamics induced by intravenous infusion of NE and angiotensin II (Ang II), at doses that increased arterial pressure by ∼25 mm Hg (20%). Renal blood flow (RBF) was determined using a Transonic probe, and superficial cortical, outer and inner medullary flows (CBF, OMBF, IMBF) as laser-Doppler fluxes. RESULTS NE decreased regional intrarenal perfusion similarly, by 16, 15 and 16% for RBF, OMBF and IMBF, respectively (all changes significant). The respective decreases after Ang II were significantly greater and clearly differentiated: 45, 32 and 22%, respectively. The renal vascular resistance increased 47 ± 4% after NE and 131 ± 11% after Ang II, indicating that the latter drug induces much more pronounced renal vasoconstriction. CONCLUSION An ∼15% decrease of renal perfusion may be taken as an indication of an impairment of renal circulation during antihypotensive NE therapy. While superiority of NE over Ang II is obvious, a further search for drugs even less harmful to renal perfusion and function is desirable.
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Affiliation(s)
- Bozena Badzyńska
- Laboratory of Renal and Body Fluid Physiology, M. Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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23
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May CN, Evans RG. Frontiers in research series: Neural, hormonal and renal interactions in long-term blood pressure control II. Introduction. Clin Exp Pharmacol Physiol 2009; 37:272-3. [PMID: 19930420 DOI: 10.1111/j.1440-1681.2009.05341.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Clive N May
- Howard Florey Institute, University of Melbourne Parkville, Victoria, Australia.
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