In vitro production of angiotensin II by isolated glomeruli

The glomerulus has several components of the renin-angiotensin system (RAS). The purpose of this study was to evaluate the ability of glomeruli isolated from adult Wistar-Kyoto rats to produce angiotensin II (ANG II). When isolated glomeruli were incubated in Krebs buffer, the peak concentration of immunoreactive angiotensin (ANG) in the incubation medium, representing simultaneous production and degradation, occurred after 15 min of incubation (3.98 +/- 0.34 pg.mg protein-1.15 min-1, of which 18% was ANG II. When 125I-labeled ANG II was incubated with isolated glomeruli, the half-life of ANG II was 6.06 min. Hence, we estimated ANG II production at 3.77 +/- 0.21 pg.mg protein-1.15 min-1. When angiotensinogen-rich serum was added to the incubation medium, ANG concentration at 15 min increased by 500-fold (1,978 +/- 44 pg.mg protein-1.15 min-1, P < 0.001). ANG concentration in the glomerular incubate responded to perturbations known to alter systemic RAS. Enalaprilat, chymostatin, propranolol, and renin antiserum decreased ANG concentration in glomerular incubate, whereas salt depletion increased this (P < 0.05). We conclude that the rat glomerulus can generate ANG II independent of neural, hormonal, or vascular control.

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Glomerular effects of angiotensin II require intrarenal factors

AJP Renal Physiology ◽

10.1152/ajprenal.1990.258.3.f717 ◽

1990 ◽

Vol 258 (3) ◽

pp. F717-F721 ◽

Cited By ~ 1

Author(s):

T. B. Wiegmann ◽

M. L. MacDougall ◽

V. J. Savin

Keyword(s):

Angiotensin Ii ◽

Rate Of Change ◽

Ang Ii ◽

Membrane Area ◽

Isolated Glomeruli ◽

Systemic Factors ◽

Glomerular Ultrafiltration

Glomerular ultrafiltration coefficient (Kf) of glomeruli isolated from kidneys of normovolemic rats decreases following infusion of angiotensin II (ANG II). Kf from isolated glomeruli after ANG II infusion in vivo and from isolated perfused kidneys following infusion of ANG II in vitro was measured to determine whether the decrease required the presence of systemic factors. Filtration was induced in vitro and the maximum rate of change in glomerular volume was used to calculate Kf. Glomerular capillary hydraulic conductivity (Lp) was calculated from Lp = Kf/A where the basement membrane area A was calculated as 3 X pi X D2. ANG II infusion in vivo in rats diminished Lp from 3.19 +/- 0.19 to 1.96 +/- 0.13 and to 1.82 +/- 0.11 microliters.min-1.mmHg-1.cm-2, respectively. ANG II infusion into isolated kidneys caused a similar decrease in Lp (3.55 +/- 0.11 to 2.37 +/- 0.07). ANG II infusion either in vivo or during isolated kidney perfusion decreases Kf and Lp. ANG II effects do not require the presence of extrarenal factors but depend on perfusion in situ since incubation of isolated glomeruli with ANG II did not alter Kf.

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Increased angiotensin II receptors in brain nuclei of DOCA-salt hypertensive rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1988.255.3.h646 ◽

1988 ◽

Vol 255 (3) ◽

pp. H646-H650 ◽

Cited By ~ 6

Author(s):

J. S. Gutkind ◽

M. Kurihara ◽

J. M. Saavedra

Keyword(s):

Angiotensin Ii ◽

Area Postrema ◽

Experimental Hypertension ◽

Ang Ii ◽

Preoptic Nucleus ◽

Salt Treatment ◽

Brain Nuclei ◽

Median Preoptic Nucleus ◽

Wistar Kyoto

We analyzed angiotensin II (ANG II) receptors by in vitro autoradiography in selective brain nuclei of control, salt-treated (1% NaCl in drinking water), deoxycorticosterone acetate (DOCA)-treated (DOCA pivalate, 25 mg/kg sc weekly), and DOCA-salt-treated (DOCA + salt treatments) uninephrectomized male Wistar-Kyoto rats. After 4 wk of treatment, only the DOCA-salt group developed hypertension. ANG II binding increased in median preoptic nucleus and subfornical organ of salt- and DOCA-treated rats. DOCA-treated rats also showed increased ANG II binding in paraventricular nucleus. DOCA-salt-treated rats showed higher ANG II binding in nucleus of the solitary tract and area postrema, as well as in the areas mentioned before. Although salt and/or DOCA treatments alone increased ANG II receptors in some brain nuclei, after combined DOCA-salt treatment there was significantly higher ANG II binding in all areas, except the median preoptic nucleus. These results suggest that increased ANG II receptors in selected brain areas may play a role in the pathophysiology of mineralocorticoid-salt experimental hypertension.

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Physiological regulation of extracellular matrix collagen and elastin in the arterial wall of rats by noradrenergic tone and angiotensin II

Journal of the Renin-Angiotensin-Aldosterone System ◽

10.1177/1470320311414752 ◽

2011 ◽

Vol 13 (1) ◽

pp. 19-28 ◽

Cited By ~ 5

Author(s):

Houcine Dab ◽

Kamel Kacem ◽

Rafik Hachani ◽

Nadra Dhaouadi ◽

Wassim Hodroj ◽

...

Keyword(s):

Extracellular Matrix ◽

Angiotensin Ii ◽

Vascular Diseases ◽

Vascular Wall ◽

Collagen I ◽

Ang Ii ◽

Physiological Regulation ◽

Collagen Iii ◽

Wistar Kyoto

The interactions between the effects of the sympathetic nervous system (SNS) and angiotensin II (ANG II) on vascular extracellular matrix (ECM) synthesis were determined in rats. The mRNA and protein content of collagen I, collagen III and elastin in the abdominal aorta (AA) and femoral artery (FA) was investigated in Wistar–Kyoto rats treated for 5 weeks with guanethidine, a sympathoplegic, losartan, an ANG II AT1 receptor (AT1R) blocker, or both. The effects of noradrenaline (NE) and ANG II on collagen III and elastin mRNA, and the receptor involved, were tested in cultured vascular smooth muscle cells (VSMCs) in vitro. Guanethidine increased collagen types I and III and decreased elastin, while losartan had an opposite effect, although without effect on collagen III. The combination of treatments abrogated changes induced by simple treatment with collagen I and elastin, but increased collagen III mRNA in AA and not in FA. NE stimulated collagen III mRNA via β receptors and elastin via α1 and α2 receptors. ANG II stimulated collagen III but inhibited elastin mRNA via AT1R. Overall, SNS and ANG II exert opposite and antagonistic effects on major components of ECM in the vascular wall. This may be of relevance for the choice of a therapeutic strategy in vascular diseases.

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Angiotensin II Upregulates Sodium-Glucose Co-Transporter2 (SGLT2) Expression and SGLT2 Inhibitor Attenuates Ang II-Induced Hypertensive Renal Injury in Mice

Clinical Science ◽

10.1042/cs20210094 ◽

2020 ◽

Author(s):

Kana N Miyata ◽

Chao-Sheng Lo ◽

Shuiling Zhao ◽

Min-Chun Liao ◽

Yuchao Pang ◽

...

Keyword(s):

Angiotensin Ii ◽

Renal Injury ◽

Linear Regression Analysis ◽

Sglt2 Inhibitor ◽

Renin Angiotensin System ◽

Mrna Levels ◽

Ang Ii ◽

Multivariable Linear Regression Analysis ◽

Renal Proximal Tubular Cells

Clinical trials indicate that sodium-glucose co-transporter 2 inhibitors (SGLT2i) improve kidney function, yet, the molecular regulation of SGLT2 expression is incompletely understood. Here, we investigated the role of the intrarenal renin-angiotensin-system (RAS) on SGLT2 expression. In adult non-diabetic participants in the Nephrotic Syndrome Study Network (NEPTUNE, N=163), multivariable linear regression analysis showed SGLT2 mRNA was significantly associated with angiotensinogen (AGT), renin, and angiotensin converting enzyme (ACE) mRNA levels (p<0.001). In vitro, angiotensin II (Ang II) dose-dependently stimulated SGLT2 expression in HK-2, human immortalized renal proximal tubular cells (RPTCs); losartan and antioxidants inhibited it. Sglt2 expression was increased in transgenic mice specifically overexpressing Agt in their RPTCs, as well as in WT mice with a single subcutaneous injection of Ang II (1.44 mg/kg). Moreover, Ang II (1000 ng/kg/min) infusion via osmotic mini-pump in WT mice for 4 weeks increased systolic blood pressure (SBP), glomerulosclerosis, tubulointerstitial fibrosis, and albuminuria; canaglifozin (Cana, 15 mg/kg/day) reversed these changes, with the exception of SBP. Fractional glucose excretion was higher in Ang II+Cana than WT+Cana, whereas Sglt2 expression was similar. Our data demonstrate a link between intrarenal RAS and SGLT2 expression and that SGLT2i ameliorates Ang II-induced renal injury independent of SBP.

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High intraluminal pressure via H2O2 upregulates arteriolar constrictions to angiotensin II by increasing the functional availability of AT1 receptors

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00205.2008 ◽

2008 ◽

Vol 295 (2) ◽

pp. H835-H841 ◽

Cited By ~ 22

Author(s):

Zsolt Bagi ◽

Nora Erdei ◽

Akos Koller

Keyword(s):

High Pressure ◽

Angiotensin Ii ◽

Renin Angiotensin System ◽

Intraluminal Pressure ◽

Ang Ii ◽

At1 Receptors ◽

Angiotensin System ◽

Dose Dependent

Previously, we found that high intraluminal pressure leads to production of reactive oxygen species (ROS) and also upregulates several components of the renin-angiotensin system in the wall of small arteries. We hypothesized that acute exposure of arterioles to high intraluminal pressure in vitro via increasing ROS production enhances the functional availability of type 1 angiotensin II (Ang II) receptors (AT1 receptors), resulting in sustained constrictions. In arterioles (∼180 μm) isolated from rat skeletal muscle, Ang II elicited dose-dependent constrictions, which decreased significantly by the second application [maximum (max.): from 59% ± 4% to 26% ± 5% at 10−8 M; P < 0.05] in the presence of 80 mmHg of intraluminal pressure. In contrast, if the arterioles were exposed to high intraluminal pressure (160 mmHg for 30 min), Ang II-induced constrictions remained substantial on the second application (max.: 51% ± 3% at 10−8 M). In the presence of Tiron and polyethylene glycol (PEG)-catalase, known to reduce the level of superoxide anion and hydrogen peroxide (H2O2), second applications of Ang II evoked similarly reduced constrictions, even after high-pressure exposure (29% ± 4% at 10−8 M). Furthermore, when arterioles were exposed to H2O2 (for 30 min, 10−7 M, at normal 80 mmHg pressure), Ang II-induced constrictions remained substantial on second applications (59% ± 5% at 10−8 M). These findings suggest that high pressure, likely via inducing H2O2 production, increases the functional availability of AT1 receptors and thus enhances Ang II-induced arteriolar constrictions. We propose that in hypertension–regardless of etiology–high intraluminal pressure, via oxidative stress, enhances the functional availability of AT1 receptors augmenting Ang II-induced constrictions.

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EDRF-angiotensin II interactions in rat juxtamedullary afferent and efferent arterioles

AJP Renal Physiology ◽

10.1152/ajprenal.1992.263.5.f900 ◽

1992 ◽

Vol 263 (5) ◽

pp. F900-F906 ◽

Cited By ~ 28

Author(s):

K. Ohishi ◽

P. K. Carmines ◽

E. W. Inscho ◽

L. G. Navar

Keyword(s):

Angiotensin Ii ◽

Renin Angiotensin System ◽

Biological Action ◽

Dependent Manner ◽

Ang Ii ◽

Synthesis Inhibitor ◽

Concentration Dependent Manner ◽

Arteriolar Resistance ◽

Constrictor Response

The in vitro blood-perfused juxtamedullary nephron technique was utilized to determine the contribution of endothelium-derived relaxing factor (EDRF) to resting renal arteriolar caliber and to evaluate the interaction between EDRF and angiotensin II (ANG II) in renal microvascular control. Video microscopy was employed to visualize rat afferent and efferent arterioles and to measure their responses to blockade of nitric oxide (NO), which has been shown to account for much of the biological action of EDRF. The NO synthesis inhibitor, N omega-nitro-L-arginine (L-NNA), elicited vasoconstriction in a concentration-dependent manner, with 1,000 microM L-NNA significantly reducing both afferent (16 +/- 3%) and efferent (13 +/- 1%) diameters. This concentration of L-NNA also blocked the vasodilator response to 10 microM acetylcholine, while responsiveness to sodium nitroprusside was maintained. Vasoconstrictor responses to 1,000 microM L-NNA were attenuated in kidneys from rats pretreated with enalaprilat or losartan, reducing afferent diameter by 7 +/- 1 (n = 8) and 3 +/- 1% (n = 10) of control, respectively. Efferent arteriolar responses to L-NNA were similarly attenuated by losartan. The constrictor response to 10 nM ANG II was not exaggerated by L-NNA, suggesting that ANG II does not stimulate EDRF synthesis. These observations indicate that EDRF is continuously released in a quantity sufficient to affect both afferent and efferent arterioles of juxtamedullary nephrons in vitro. Furthermore, ANG II blockade attenuates the vasoconstriction elicited by L-NNA, suggesting that EDRF interacts with the renin-angiotensin system to control juxtamedullary afferent and efferent arteriolar resistance.

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Preovulatory changes in the angiotensin II system in bovine follicles

Reproduction Fertility and Development ◽

10.1071/rd11316 ◽

2013 ◽

Vol 25 (3) ◽

pp. 539 ◽

Cited By ~ 13

Author(s):

Lucas C. Siqueira ◽

Joabel T. dos Santos ◽

Rogério Ferreira ◽

Robson Souza dos Santos ◽

Adelina M. dos Reis ◽

...

Keyword(s):

Angiotensin Ii ◽

Granulosa Cells ◽

Renin Angiotensin System ◽

Mrna Levels ◽

Ang Ii ◽

Hormone Production ◽

Angiotensin System ◽

Renin Angiotensin ◽

Theca Cells

The present study evaluated whether the gonadotrophin surge modulates components of the renin–angiotensin system and whether angiotensin II (Ang II) plays a role in the production of hormones by follicular cells during the ovulatory process. In Experiment 1, cows were ovariectomised at various times (0, 3, 6, 12 and 24h) after GnRH injection to obtain preovulatory follicles. The concentration of Ang II in follicular fluid increased after GnRH and reached a peak at 24h, concomitant with the peak of angiotensinogen (AGT) mRNA expression in granulosa cells. AGT mRNA was not expressed in theca cells. Ang II receptor type 2 and angiotensin-converting enzyme mRNA levels were transiently upregulated in theca cells. In Experiment 2, an in vitro culture was used to determine whether Ang II could modulate hormone production by healthy dominant follicles. In the absence of LH, Ang II did not alter hormonal production by either theca or granulosa cells. Ang II plus LH increased progesterone and prostaglandin secretion by granulosa cells. In summary, the renin–angiotensin system is actively controlled during the preovulatory period and Ang II amplifies the stimulatory effects of LH on the secretion of progesterone and prostaglandins by granulosa cells.

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AT1 and AT2 receptors modulate renal tubular cell necroptosis in angiotensin II-infused renal injury mice

Scientific Reports ◽

10.1038/s41598-019-55550-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Yongjun Zhu ◽

Hongwang Cui ◽

Jie Lv ◽

Haiqin Liang ◽

Yanping Zheng ◽

...

Keyword(s):

Angiotensin Ii ◽

Renal Injury ◽

Critical Role ◽

Kidney Injury ◽

Renin Angiotensin System ◽

Tubular Cell ◽

Tubular Damage ◽

Renal Tubular Cell ◽

Ang Ii ◽

Renal Tubular

AbstractAbnormal renin-angiotensin system (RAS) activation plays a critical role in the initiation and progression of chronic kidney disease (CKD) by directly mediating renal tubular cell apoptosis. Our previous study showed that necroptosis may play a more important role than apoptosis in mediating renal tubular cell loss in chronic renal injury rats, but the mechanism involved remains unknown. Here, we investigate whether blocking the angiotensin II type 1 receptor (AT1R) and/or angiotensin II type 2 receptor (AT2R) beneficially alleviates renal tubular cell necroptosis and chronic kidney injury. In an angiotensin II (Ang II)-induced renal injury mouse model, we found that blocking AT1R and AT2R effectively mitigates Ang II-induced increases in necroptotic tubular epithelial cell percentages, necroptosis-related RIP3 and MLKL protein expression, serum creatinine and blood urea nitrogen levels, and tubular damage scores. Furthermore, inhibition of AT1R and AT2R diminishes Ang II-induced necroptosis in HK-2 cells and the AT2 agonist CGP42112A increases the percentage of necroptotic HK-2 cells. In addition, the current study also demonstrates that Losartan and PD123319 effectively mitigated the Ang II-induced increases in Fas and FasL signaling molecule expression. Importantly, disruption of FasL significantly suppressed Ang II-induced increases in necroptotic HK-2 cell percentages, and necroptosis-related proteins. These results suggest that Fas and FasL, as subsequent signaling molecules of AT1R and AT2R, might involve in Ang II-induced necroptosis. Taken together, our results suggest that Ang II-induced necroptosis of renal tubular cell might be involved both AT1R and AT2R and the subsequent expression of Fas, FasL signaling. Thus, AT1R and AT2R might function as critical mediators.

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Effects of dietary salt changes on renal renin-angiotensin system in rats

AJP Renal Physiology ◽

10.1152/ajprenal.00321.2001 ◽

2002 ◽

Vol 283 (5) ◽

pp. F995-F1002 ◽

Cited By ~ 48

Author(s):

Catherine Ingert ◽

Michèle Grima ◽

Catherine Coquard ◽

Mariette Barthelmebs ◽

Jean-Louis Imbs

Keyword(s):

Renal Cortex ◽

Salt Content ◽

Renin Angiotensin System ◽

Fold Increase ◽

Kidney Cortex ◽

Ang Ii ◽

Dietary Salt ◽

High Sodium ◽

Ace Activity ◽

Wistar Kyoto

Renin (RA) and angiotensin-converting enzyme (ACE) activities and angiotensinogen, ANG I, and ANG II levels were measured in the kidney (cortex and medulla) and plasma of Wistar-Kyoto rats on a low-sodium (LS; 0.025% NaCl; n= 8), normal-sodium (NS; 1% NaCl; n = 7), or high-sodium (HS; 8% NaCl; n = 7) diet for 21 days. RA, ANG I, and ANG II levels increased in a manner inversely related to sodium content of the diet in both plasma and renal tissues. The LS diet resulted in a 16-, 2.8-, and 1.8-fold increase in plasma RA, ANG I, and ANG II levels, respectively, compared with those in HS rats. In the renal cortex and medulla, RA, ANG I, and ANG II levels were also increased by diminution of dietary salt content but, in contrast to plasma, ANG II levels increased much more than RA or ANG I levels [5.4 (cortex)- and 4.7 (medulla)-fold compared with HS rats]. In summary, we demonstrated variations of ANG II levels in the kidney during dietary salt modifications. Our results confirm that RA and ACE activity are not the steps limiting intrarenal ANG II levels. Nevertheless, despite RA and ACE activity differences between renal cortex and medulla, ANG I and ANG II levels are equivalent in these two tissues; these results argue against a compartmentalization of RAS in these two intrarenal areas.

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