Prevention of hemorrhage-induced renal vasoconstriction and hypoxia by angiotensin II type 1 receptor antagonism in pigs

Angiotensin II (AngII) is a potent vasoconstrictor and may reduce renal blood flow (RBF), causing renal hypoxia. Hypotensive hemorrhage elevates plasma AngII levels and is associated with increased risk of acute kidney injury. We hypothesized that AngII 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's acetate (vehicle-treated, n=8). Hemorrhage was induced by continuous aspiration of blood to reach and sustain mean arterial blood pressure of <50 mmHg for 30 minutes. Plasma AngII levels, hemodynamics and oxygenation were assessed 60 minutes pre-hemorrhage, 30-minutes after the start of hemorrhage and 60 minutes post-hemorrhage. Erythropoietin mRNA was analyzed in cortical and medullary tissue sampled at the end of the experiment. Hypotensive hemorrhage increased plasma AngII 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, AngII antagonism alleviates prolonged renal vasoconstriction and renal hypoxia in a large animal model of hypotensive hemorrhage.

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Pre-treatment with the angiotensin receptor 1 blocker losartan protects renal blood flow and oxygen delivery after propofol-induced hypotension in pigs

Scientific Reports ◽

10.1038/s41598-020-74640-6 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Stephanie Franzén ◽

Robert Frithiof

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Angiotensin Ii ◽

Renal Blood Flow ◽

Oxygen Delivery ◽

Induced Hypotension ◽

Renal Vasoconstriction ◽

Arterial Blood ◽

Pre Treatment ◽

Renal Oxygen

Abstract Hypotensive events are strongly correlated to the occurrence of perioperative acute kidney injury, but the underlying mechanisms for this are not completely elucidated. We hypothesised that anaesthesia-induced hypotension causes renal vasoconstriction and decreased oxygen delivery via angiotensin II-mediated renal vasoconstriction. Pigs were anaesthetised, surgically prepared and randomised to vehicle/losartan treatment (0.15 mg*kg−1). A deliberate reduction in arterial blood pressure was caused by infusion of propofol (30 mg*kg−1) for 10 min. Renal function and haemodynamics were recorded 60 min before and after hypotension. Propofol induced hypotension in all animals (p < 0.001). Renal blood flow (RBF) and renal oxygen delivery (RDO2) decreased significantly regardless of treatment but more so in vehicle-treated compared to losartan-treated (p = 0.001, p = 0.02, respectively). During recovery RBF and RDO2 improved to a greater extent in the losartan-treated compared to vehicle-treated (+ 28 ml*min−1, 95%CI 8–50 ml*min−1, p = 0.01 and + 3.1 ml*min−1, 95%CI 0.3–5.8 ml*min−1, p = 0.03, respectively). Sixty minutes after hypotension RBF and RDO2 remained depressed in vehicle-treated, as renal vascular resistance was still increased (p < 0.001). In losartan-treated animals RBF and RDO2 had normalised. Pre-treatment with losartan improved recovery of renal blood flow and renal oxygen delivery after propofol-induced hypotension, suggesting pronounced angiotensin II-mediated renal vasoconstriction during blood pressure reductions caused by anaesthesia.

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A Large Animal Model for Acute Kidney Injury by Temporary Bilateral Renal Artery Occlusion

Journal of Visualized Experiments ◽

10.3791/62230 ◽

2021 ◽

Author(s):

Ilias P. Doulamis ◽

Alvise Guariento ◽

Mossab Y. Saeed ◽

Rio S. Nomoto ◽

Thomas Duignan ◽

...

Keyword(s):

Acute Kidney Injury ◽

Animal Model ◽

Renal Artery ◽

Kidney Injury ◽

Artery Occlusion ◽

Large Animal Model ◽

Large Animal ◽

Renal Artery Occlusion ◽

Bilateral Renal Artery

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Autoregulation assessment by direct visualisation of pial arterial blood flow in the piglet brain

Scientific Reports ◽

10.1038/s41598-019-50046-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

S. P. Klein ◽

V. De Sloovere ◽

G. Meyfroidt ◽

B. Depreitere

Keyword(s):

Blood Flow ◽

Brain Injury ◽

Therapeutic Interventions ◽

Arterial Blood Flow ◽

Large Animal Model ◽

Large Animal ◽

Main Site ◽

Cranial Window ◽

Arterial Blood ◽

The Impact

Abstract Impairment of cerebrovascular autoregulation (CAR) is common after brain injury, although the pathophysiology remains elusive. The mechanisms of vascular dysregulation, their impact on brain function, and potential therapeutic implications are still incompletely understood. Clinical assessment of CAR remains challenging. Observational studies suggest that CAR impairment is associated with worse outcomes, and that optimization of cerebral blood flow (CBF) by individual arterial blood pressure (ABP) targets could potentially improve outcome. We present a porcine closed cranial window model that measures the hemodynamic response of pial arterioles, the main site of CBF control, based on changes in their diameter and red blood cell velocity. This quantitative direct CAR assessment is compared to laser Doppler flow (LDF). CAR breakpoints are determined by segmented regression analysis and validated using LDF and brain tissue oxygen pressure. Using a standardized cortical impact, CAR impairment in traumatic brain injury can be studied using our method of combining pial arteriolar diameter and RBC velocity to quantify RBC flux in a large animal model. The model has numerous potential applications to investigate CAR physiology and pathophysiology of CAR impairment after brain injury, the impact of therapeutic interventions, drugs, and other confounders, or to develop personalized ABP management strategies.

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Effect of Low-Frequency Therapeutic Ultrasound on Induction of Nitric Oxide in CKD: Potential to Prevent Acute Kidney Injury

Kidney Diseases ◽

10.1159/000509819 ◽

2020 ◽

Vol 6 (6) ◽

pp. 453-460

Author(s):

Michael W. Dae ◽

Kathleen D. Liu ◽

Richard J. Solomon ◽

Dong W. Gao ◽

Carol A. Stillson

Keyword(s):

Nitric Oxide ◽

Acute Kidney Injury ◽

Animal Model ◽

Blood Flow ◽

Radionuclide Imaging ◽

Therapeutic Ultrasound ◽

Low Frequency ◽

Kidney Injury ◽

Large Animal Model ◽

Large Animal

Introduction: Post-contrast acute kidney injury (PC-AKI) develops in a significant proportion of patients with CKD after invasive cardiology procedures and is strongly associated with adverse outcomes. Objective: We sought to determine whether increased intrarenal nitric oxide (NO) would prevent PC-AKI. Methods: To create a large animal model of CKD, we infused 250 micron particles into the renal arteries in 56 ± 8 kg pigs. We used a low-frequency therapeutic ultrasound device (LOTUS – 29 kHz, 0.4 W/cm2) to induce NO release. NO and laser Doppler probes were used to assess changes in NO content and blood flow. Glomerular filtration rate (GFR) was measured by technetium-diethylene-triamine-pentaacetic acid (Tc-99m-DTPA) radionuclide imaging. PC-AKI was induced by intravenous infusion of 7 cm3/kg diatrizoate. In patients with CKD, we measured GFR at baseline and during LOTUS using Tc-99m--DTPA radionuclide imaging. Results: In the pig model, CKD developed over 4 weeks (serum creatinine [Cr], mg/dL, 1.0 ± 0.2–2.6 ± 0.9, p < 0.01, n = 12). NO and renal blood flow (RBF) increased in cortex and medulla during LOTUS. GFR increased 75 ± 24% (p = 0.016, n = 3). PC-AKI developed following diatrizoate i.v. infusion (Cr 2.6 ± 0.7 baseline to 3.4 ± 0.6 at 24 h, p < 0.01, n = 3). LOTUS (starting 15 min prior to contrast and lasting for 90 min) prevented PC-AKI in the same animals 1 week later (Cr 2.5 ± 0.4 baseline to 2.6 ± 0.7 at 24 h, p = ns, n = 3). In patients with CKD (n = 10), there was an overall 25% increase in GFR in response to LOTUS (p < 0.01). Conclusions: LOTUS increased intrarenal NO, RBF, and GFR and prevented PC-AKI in a large animal model of CKD, and significantly increased GFR in patients with CKD. This novel approach may provide a noninvasive nonpharmacological means to prevent PC-AKI in high-risk patients.

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Sustained phenotypic correction of hemophilia B dogs with a factor IX null mutation by liver-directed gene therapy

Blood ◽

10.1182/blood.v99.8.2670 ◽

2002 ◽

Vol 99 (8) ◽

pp. 2670-2676 ◽

Cited By ~ 241

Author(s):

Jane D. Mount ◽

Roland W. Herzog ◽

D. Michael Tillson ◽

Susan A. Goodman ◽

Nancy Robinson ◽

...

Keyword(s):

Gene Therapy ◽

Coagulation Factor ◽

Factor Ix ◽

Hemophilia B ◽

Large Animal Model ◽

Null Mutation ◽

Large Animal ◽

Adeno Associated Virus ◽

Increased Risk

Abstract Hemophilia B is an X-linked coagulopathy caused by absence of functional coagulation factor IX (FIX). Using adeno-associated virus (AAV)–mediated, liver-directed gene therapy, we achieved long-term (> 17 months) substantial correction of canine hemophilia B in 3 of 4 animals, including 2 dogs with an FIX null mutation. This was accomplished with a comparatively low dose of 1 × 1012 vector genomes/kg. Canine FIX (cFIX) levels rose to 5% to 12% of normal, high enough to result in nearly complete phenotypic correction of the disease. Activated clotting times and whole blood clotting times were normalized, activated partial thromboplastin times were substantially reduced, and anti-cFIX was not detected. The fourth animal, also a null mutation dog, showed transient expression (4 weeks), but subsequently developed neutralizing anti-cFIX (inhibitor). Previous work in the canine null mutation model has invariably resulted in inhibitor formation following treatment by either gene or protein replacement therapies. This study demonstrates that hepatic AAV gene transfer can result in sustained therapeutic expression in a large animal model characterized by increased risk of a neutralizing anti-FIX response.

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High-Dose Estradiol-Replacement Therapy Enhances the Renal Vascular Response to Angiotensin II via an AT2-Receptor Dependent Mechanism

Advances in Pharmacological Sciences ◽

10.1155/2015/682745 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7

Author(s):

Tahereh Safari ◽

Mehdi Nematbakhsh ◽

Roger G. Evans ◽

Kate M. Denton

Keyword(s):

Angiotensin Ii ◽

Replacement Therapy ◽

Hormone Replacement ◽

Renal Perfusion ◽

Ovariectomized Rats ◽

High Dose ◽

Ang Ii ◽

Renal Vasoconstriction ◽

Increased Risk ◽

Angiotensin Type 2 Receptor

Physiological levels of estrogen appear to enhance angiotensin type 2 receptor- (AT2R-) mediated vasodilatation. However, the effects of supraphysiological levels of estrogen, analogous to those achieved with high-dose estrogen replacement therapy in postmenopausal women, remain unknown. Therefore, we pretreated ovariectomized rats with a relatively high dose of estrogen (0.5 mg/kg/week) for two weeks. Subsequently, renal hemodynamic responses to intravenous angiotensin II (Ang II, 30–300 ng/kg/min) were tested under anesthesia, while renal perfusion pressure was held constant. The role of AT2R was examined by pretreating groups of rats with PD123319 or its vehicle. Renal blood flow (RBF) decreased in a dose-related manner in response to Ang II. Responses to Ang II were enhanced by pretreatment with estradiol. For example, at 300 ng kg−1 min−1, Ang II reduced RBF by45.7±1.9% in estradiol-treated rats but only by27.3±5.1% in vehicle-treated rats. Pretreatment with PD123319 blunted the response of RBF to Ang II in estradiol-treated rats, so that reductions in RBF were similar to those in rats not treated with estradiol. We conclude that supraphysiological levels of estrogen promote AT2R-mediated renal vasoconstriction. This mechanism could potentially contribute to the increased risk of cardiovascular disease associated with hormone replacement therapy using high-dose estrogen.

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Effects of Angiotensin II Type 1A Receptor on ACE2, Neprilysin and KIM-1 in Two Kidney One Clip (2K1C) Model of Renovascular Hypertension

Frontiers in Pharmacology ◽

10.3389/fphar.2020.602985 ◽

2021 ◽

Vol 11 ◽

Author(s):

Laale F. Alawi ◽

Sanjeev Dhakal ◽

Sana E. Emberesh ◽

Harshal Sawant ◽

Anhar Hosawi ◽

...

Keyword(s):

Blood Pressure ◽

Angiotensin Ii ◽

Mouse Model ◽

Cell Injury ◽

Kidney Injury ◽

Ang Ii ◽

Knock Out ◽

Contralateral Kidney ◽

Arterial Blood ◽

Expression And Activity

Activation of the renin angiotensin system plays a pivotal role in the regulation of blood pressure, which is mainly attributed to the formation of angiotensin-II (Ang II). The actions of Ang II are mediated through binding to the Ang-II type 1 receptor (AT1R) which leads to increased blood pressure, fluid retention, and aldosterone secretion. In addition, Ang II is also involved in cell injury, vascular remodeling, and inflammation. The actions of Ang II could be antagonized by its conversion to the vasodilator peptide Ang (1–7), partly generated by the action of angiotensin converting enzyme 2 (ACE2) and/or neprilysin (NEP). Previous studies demonstrated increased urinary ACE2 shedding in the db/db mouse model of diabetic kidney disease. The aim of the study was to investigate whether renal and urinary ACE2 and NEP are altered in the 2K1C Goldblatt hypertensive mice. Since AT1R is highly expressed in the kidney, we also researched the effect of global deletion of AT1R on renal and urinary ACE2, NEP, and kidney injury marker (KIM-1). Hypertension and albuminuria were induced in AT1R knock out (AT1RKO) and WT mice by unilateral constriction of the renal artery of one kidney. The 24 h mean arterial blood pressure (MAP) was measured using radio-telemetry. Two weeks after 2K1C surgery, MAP and albuminuria were significantly increased in WT mice compared to AT1RKO mice. Results demonstrated a correlation between MAP and albuminuria. Unlike db/db diabetic mice, ACE2 and NEP expression and activities were significantly decreased in the clipped kidney of WT and AT1RKO compared with the contralateral kidney and sham control (p < 0.05). There was no detectable urinary ACE2 and NEP expression and activity in 2K1C mice. KIM-1 was significantly increased in the clipped kidney of WT and AT1KO (p < 0.05). Deletion of AT1R has no effect on the increased urinary KIM-1 excretion detected in 2K1C mice. In conclusion, renal injury in 2K1C Goldblatt mouse model is associated with loss of renal ACE2 and NEP expression and activity. Urinary KIM-1 could serve as an early indicator of acute kidney injury. Deletion of AT1R attenuates albuminuria and hypertension without affecting renal ACE2, NEP, and KIM-1 expression.

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Abstract 144: Roles of Aging and Cellular Senescence in Intracranial Aneurysm Rupture

Stroke ◽

10.1161/str.51.suppl_1.144 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Hiroki Sato ◽

Taichi Ikedo ◽

Tetsuro Kimura ◽

James Purcell ◽

Samantha Merrow ◽

...

Keyword(s):

Intracranial Aneurysm ◽

Older Patients ◽

Cerebral Arteries ◽

Sirtuin 1 ◽

Vehicle Group ◽

Mrna Levels ◽

Younger Patients ◽

Aneurysmal Rupture ◽

Rupture Rate ◽

Increased Risk

Background: Aging is an independent risk factor for the rupture of intracranial aneurysm. One of the hallmarks of aging is chronic tissue inflammation. Sirtuin-1 keeps inflammation in check through the deacetylation of various proteins. It is well known that the levels of Sirtuin-1 in vascular tissues decrease with aging, resulting in chronic vascular inflammation. Age-dependent decrease in Sirtuin-1 may explain the link between aging and increased risk for aneurysmal rupture. Hypothesis: Reduction of Sirtuin-1 promotes aneurysmal rupture by inducing sustained aneurysmal wall inflammation. Methods: First, we assessed the levels of Sirtuin-1 expression in intracranial aneurysm tissues from patients older than 70 y.o. and compared with those from the younger patients (40 to 50 y.o.). Second, using a mouse model, we tested effects of Sirtuin-1 specific activator SRT1720 (15mg/kg/day) and specific inhibitor EX-527 (2.5mg/kg/day) on the development of aneurysmal rupture. In addition, we assessed the mRNA expression of inflammatory cytokines (IL-6, IL-1beta, MCP-1, and MMP-9) in cerebral arteries and aneurysms in mice treated with vehicle, SRT1720, or EX-527. Results: Sirtuin-1 expression levels in intracranial aneurysm tissues from the older patients were lower than those from the younger patients. The pharmacological inhibition of Sirtuin-1 increased rupture rate in mice (vehicle vs. EX-527: 58% vs. 88%, P <0.05). Moreover, the pharmacological activation of Sirtuin-1 reduced rupture rate in mice (vehicle vs. SRT1720: 80% vs. 50%, P <0.05). Levels of IL-6, MMP-9 mRNAs in cerebral arteries were significantly higher in the inhibitor group than in the vehicle group. On the other hand, both mRNA levels were lower in the activator group than in the vehicle group. Conclusions: Our findings suggest that the reduction of Sirtuin-1 promotes aneurysmal rupture via the induction of inflammation. This may explain the increased risk for aneurysmal subarachnoid hemorrhage in the older population. Our findings may become a basis for future studies to develop new therapies that target Sirtuin-1 for the prevention of aneurysmal rupture, especially in older patients.

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Abstract P141: Immunosuppressant Treatment Attenuates Augmentation Of Intrarenal NLRP-3 Inflammasome In Angiotensin II-dependent Hypertension

Hypertension ◽

10.1161/hyp.76.suppl_1.p141 ◽

2020 ◽

Vol 76 (Suppl_1) ◽

Author(s):

Ryousuke Satou ◽

Martha G Franco ◽

Akemi Katsurada ◽

Courtney M Dugas ◽

L G NAVAR

Keyword(s):

Angiotensin Ii ◽

Nlrp3 Inflammasome ◽

Bacterial Infections ◽

Kidney Injury ◽

Control Group ◽

Inflammasome Activation ◽

Mrna Levels ◽

Ang Ii ◽

Sprague Dawley ◽

Normotensive Control

Activated inflammasomes enhance maturation of pro-inflammatory cytokines, which facilitates the development of kidney injury. NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3), one of major subunits in the inflammasome complex, plays a crucial role in innate immunity and inflammation. Although NLRP3 inflammasome is activated by ATP-P2Y7 axis and reactive oxygen species, the expression of pro-NLRP3 is promoted by NF-κB activated by cytokines or PAMPs/DAMPs. Thus, we hypothesized that mycophenolate mofetil (MMF), an immunosuppressant, attenuates augmentation of intrarenal NLRP3 and consequent progression of kidney injury in angiotensin II (Ang II)-dependent hypertension. Ang II (80 ng/min) was infused with/without daily MMF administration (50 ng/kg) to Sprague-Dawley rats for 2 weeks. mRNA levels of intrarenal NLRP3 and AIM2, which forms another type of inflammasome complex by viral or bacterial infections, were measured by droplet digital PCR. Furthermore, kidney injury was evaluated. MMF treatment mitigated Ang II-induced macrophage infiltration into kidneys, suggesting immunosuppression by the drug. Ang II infusion significantly increased intrarenal NLRP3 mRNA levels (normotensive control group: 4.12±1.1 copies/ng RNA vs. Ang II-infused group: 9.96±1.8 copies, N=5). The elevated NLRP3 expression in kidneys of Ang II-infused rats was attenuated by MMF treatment (6.24±1.4 copies). In contrast, intrarenal AIM2 levels were lower than NLRP3 in the control group and the levels were not altered by Ang II infusion or MMF treatment (normotensive control group: 0.42±0.1 copies, Ang II-infused group: 0.35±0.06 copies and Ang II+MMF group: 0.35±0.08 copies). Urinary protein and angiotensinogen levels were elevated in Ang II-infused rats and MMF treatment suppressed the augmentations. Histological analyses also showed the development of kidney injury including mesangial expansion and tubulointerstitial fibrosis observed in the hypertensive rats, but these injury markers were mitigated by MMF. These results demonstrate activation of the NLRP3 inflammasome in Ang II dependent hypertension and indicate that immunosuppression by MMF mitigates the inflammasome activation, which contributes to attenuation of the kidney injury.

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