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

2021 ◽  
Vol 11 ◽  
Author(s):  
Laale F. Alawi ◽  
Sanjeev Dhakal ◽  
Sana E. Emberesh ◽  
Harshal Sawant ◽  
Anhar Hosawi ◽  
...  

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.

2015 ◽  
Vol 308 (10) ◽  
pp. C803-C812 ◽  
Author(s):  
Colin N. Young ◽  
Anfei Li ◽  
Frederick N. Dong ◽  
Julie A. Horwath ◽  
Catharine G. Clark ◽  
...  

Endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) generation in the brain circumventricular subfornical organ (SFO) mediate the central hypertensive actions of Angiotensin II (ANG II). However, the downstream signaling events remain unclear. Here we tested the hypothesis that angiotensin type 1a receptors (AT1aR), ER stress, and ROS induce activation of the transcription factor nuclear factor-κB (NF-κB) during ANG II-dependent hypertension. To spatiotemporally track NF-κB activity in the SFO throughout the development of ANG II-dependent hypertension, we used SFO-targeted adenoviral delivery and longitudinal bioluminescence imaging in mice. During low-dose infusion of ANG II, bioluminescence imaging revealed a prehypertensive surge in NF-κB activity in the SFO at a time point prior to a significant rise in arterial blood pressure. SFO-targeted ablation of AT1aR, inhibition of ER stress, or adenoviral scavenging of ROS in the SFO prevented the ANG II-induced increase in SFO NF-κB. These findings highlight the utility of bioluminescence imaging to longitudinally track transcription factor activation during the development of ANG II-dependent hypertension and reveal an AT1aR-, ER stress-, and ROS-dependent prehypertensive surge in NF-κB activity in the SFO. Furthermore, the increase in NF-κB activity before a rise in arterial blood pressure suggests a causal role for SFO NF-κB in the development of ANG II-dependent hypertension.


Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Xiao C Li ◽  
Manoocher Soleimani ◽  
Hoang Nguyen ◽  
Hong Li ◽  
Jia L Zhuo

An intracrine mitochondrial renin-angiotensin system (RAS) has recently been identified in various animal and human tissues, but whether the mitochondrial RAS plays a physiological role in the regulation of blood pressure remains unknown. The present study tested whether overexpression of an intracellular angiotensin II fusion protein, ECFP/ANG II, selectively in the mitochondria of the proximal tubules alters blood pressure, and whether the effects may involve AT 1a receptors and the Na + /H + exchanger 3 (NHE3). An adenoviral vector encoding ECFP/ANG II, a mitochondria targeting sequence, and the sglt2 promoter, Ad-sglt2-mito-ECFP/ANG II, was constructed for proximal tubule- and mitochondria-specific overexpression for 2 weeks. In adult male C57BL/6J mice, overexpression of mito-ECFP/ANG II in the mitochondria of the proximal tubules increased systolic blood pressure (SBP) significantly (Control: 116 ± 3 vs. mito-ECFP/ANG II: 128 ± 3 mmHg; p <0.01, n=15). The blood pressure-increasing effect of Ad-sglt2-mito-ECFP/ANG II was blocked in proximal tubule-specific AT 1a -KO mice (Control: 105 ± 2 vs. mito-ECFP/ANG II: 104 ± 4 mmHg; n.s ., n=7), or in proximal tubule-specific NHE3-KO mice (Control: 108 ± 3 vs. mito-ECFP/ANG II: 107 ± 3 mmHg; n.s ., n=13), respectively. In further experiments, mouse proximal tubule cells were transfected with Ad-sglt2-mito-ECFP/ANG II for 48 h and treated with the AT 1 blocker losartan (10 μM) or the AT 2 blocker PD123319 (10 μM) to measure mitochondrial respiratory and glycolytic function using Seahorse XF Cell Mito and XF Glycolysis Stress Tests. The mito-ECFP/ANG II expression was robust and colocalized with MitoTracker® Red FM. Overexpression of mito-ECFP/ANG II markedly increased oxygen consumption rate (OCR) (Control: 139.4 ± 9.2 vs. mito-ECFP/ANG II: 236.3 ± 12.6 pmol/min; p <0.01, n=12) and extracellular acidification rate (ECAR) (Control: 8.8 ± 0.6 vs. mito-ECFP/ANG II: 11.8 ± 1.2 mpH/min; p <0.01, n=12), respectively. Losartan blocked the effects of mito-ECFP/ANG II on OCR and ECAR, whereas PD123319 had no effect. We conclude that intracellular ANG II may activate AT 1 receptors in the mitochondria of the proximal tubules to alter mitochondrial respiratory and glycolytic function and arterial blood pressure.


1993 ◽  
Vol 265 (3) ◽  
pp. R591-R595 ◽  
Author(s):  
R. L. Thunhorst ◽  
S. J. Lewis ◽  
A. K. Johnson

Intracerebroventricular (icv) infusion of angiotensin II (ANG II) in rats elicits greater water intake under hypotensive, compared with normotensive, conditions. The present experiments used sinoaortic baroreceptor-denervated (SAD) rats and sham-operated rats to examine if the modulatory effects of arterial blood pressure on water intake in response to icv ANG II are mediated by arterial baroreceptors. Mean arterial blood pressure (MAP) was raised or lowered by intravenous (i.v.) infusions of phenylephrine (1 or 10 micrograms.kg-1 x min-1) or minoxidil (25 micrograms.kg-1 x min-1), respectively. The angiotensin-converting enzyme inhibitor captopril (0.33 mg/min) was infused i.v. to prevent the endogenous formation of ANG II during testing. Urinary excretion of water and solutes was measured throughout. Water intake elicited by icv ANG II was inversely related to changes in MAP. Specifically, rats drank more water in response to icv ANG II when MAP was reduced by minoxidil but drank less water when MAP was elevated by phenylephrine. The influence of changing MAP on the icv ANG II-induced drinking responses was not affected by SAD. These results suggest that the modulatory effects of arterial blood pressure on icv ANG II-induced drinking can occur in the absence of sinoaortic baroreceptor input.


1983 ◽  
Vol 245 (4) ◽  
pp. H667-H673
Author(s):  
D. B. Averill ◽  
A. M. Scher ◽  
E. O. Feigl

The participation of angiotensin II (ANG II) in the maintenance of arterial blood pressure during hypotensive hemorrhage was examined in unanesthetized, baroreceptor-denervated dogs. When mean aortic blood pressure was reduced to 69.0 +/- 2.2 mmHg, plasma renin activity increased from 0.6 +/- 0.3 ng ANG I X ml-1 X h-1 during the prehemorrhage control period to 4.5 +/- 1.6. Twenty minutes after the hemorrhage, mean aortic blood pressure rose to 78.9 +/- 3.1 mmHg. Subsequent infusion of the angiotensin II antagonist saralasin (5.2-14.0 micrograms X kg-1 X min-1) decreased mean aortic pressure to 59.6 +/- 3.3 mmHg. When 5% dextrose was infused in place of saralasin, mean aortic pressure was 79.3 +/- 4.3 mmHg. The lower aortic blood pressure caused by saralasin infusion was the result of a significant decrease in total peripheral resistance. Resistance was 10.3 +/- 3.2 mmHg X l-1 X min lower during saralasin infusion than during dextrose infusion. We conclude that baroreceptor reflexes are not essential for the elevation of plasma renin activity during hemorrhage. In baroreceptor-denervated dogs subjected to hypotensive hemorrhage, the increased formation of ANG II has a vasoconstrictor action that contributes to the maintenance of arterial blood pressure.


2011 ◽  
Vol 300 (3) ◽  
pp. R624-R629 ◽  
Author(s):  
Toshiyoshi Matsukawa ◽  
Takenori Miyamoto

We investigated the effect of the intravenous infusion of atrial natriuretic peptide (ANP) on the response of plasma arginine vasopressin (AVP) levels to intravenous infusion of angiotensin II (ANG II) in healthy individuals. Intravenous infusion of ANP (10 ng·kg−1·min−1) slightly but significantly decreased plasma AVP levels, while intravenous infusion of ANG II (10 ng·kg−1·min−1) resulted in slightly increased plasma AVP levels. ANG II infused significant elevations in arterial blood pressure and central venous pressure (CVP). Because the elevation in blood pressure could have potentially inhibited AVP secretion via baroreceptor reflexes, the effect of ANG II on blood pressure was attenuated by the simultaneous infusion of nitroprusside. ANG II alone produced a remarkable increase in plasma AVP levels when infused with nitroprusside, whereas the simultaneous ANP intravenous infusion (10 ng·kg−1·min−1) abolished the increase in plasma AVP levels induced by ANG II when blood pressure elevation was attenuated by nitroprusside. Thus, ANG II increased AVP secretion and ANP inhibited not only basal AVP secretion but also ANG II-stimulated AVP secretion in humans. These findings support the hypothesis that circulating ANP modulates AVP secretion, in part, by antagonizing the action of circulating ANG II.


2007 ◽  
Vol 292 (4) ◽  
pp. R1472-R1478 ◽  
Author(s):  
Trinity Vera ◽  
Silvia Kelsen ◽  
Licy L. Yanes ◽  
Jane F. Reckelhoff ◽  
David E. Stec

Heme oxygenase-1 (HO-1) induction can attenuate the development of angiotensin II (ANG II)-dependent hypertension. However, the mechanism by which HO-1 lowers blood pressure in this model is not clear. The goal of this study was to test the hypothesis that induction of HO-1 in the kidney can attenuate the increase in reactive oxygen species (ROS) generation in the kidney that occurs during ANG II-dependent hypertension. Mice were divided into four groups, control (Con), cobalt protoporphyrin (CoPP), ANG II, and ANG II + CoPP. CoPP treatment (50 mg/kg) was administered in a single subcutaneous injection 2 days prior to implantation of an osmotic minipump that infused ANG II at a rate of 1 μg·kg−1·min−1. At the end of this period, mean arterial blood pressure (MAP) averaged 93 ± 5, 90 ± 5, 146 ± 8, and 105 ± 6 mmHg in Con, CoPP-, ANG II-, and ANG II + CoPP-treated mice. To determine whether HO-1 induction resulted in a decrease in ANG II-stimulated ROS generation in the renal medulla, superoxide production was measured. Medullary superoxide production was increased by ANG II infusion and normalized in mice pretreated with CoPP. The reduction in ANG II-mediated superoxide production in the medulla with CoPP was associated with a decrease in extracellular superoxide dismutase protein but an increase in catalase protein and activity. These results suggest that reduction in superoxide and possibly hydrogen peroxide production in the renal medulla may be a potential mechanism by which induction of HO-1 with CoPP lowers blood pressure in ANG-II dependent hypertension.


2021 ◽  
Author(s):  
Mona K. Tawfik ◽  
mohammed keshawy ◽  
Samy Makary

Abstract Diabetic nephropathy (DN) is a consequence of diabetes mellitus (DM). DM is associated temporal changes in renal angiotensin II (ANG II) release and multiple mediators leading to DN. These changes were evaluated using early ANG II blocker valsartan as a DN renoprotective drug. Adult male Wister rats were divided into (i) vehicle group; (ii) valsartan received oral 30 mg/Kg/day; (iii) diabetic received single 50 mg/Kg intraperitoneal streptozotocin injection; (iv) renoprotection, valsartan treated-diabetic rats after 7 days from DM. Other group of diabetic animals assigned to receive late valsartan intervention from week 9 to 12 of DM. The renoprotective effect evaluated at 4th, 8th, 12th weeks. DN effects on urine albumin excretion, blood pressure and renal ANG II were measured. Urinary nephrin and kidney injury molecule-1 biomarkers, renal ANGPTL2, and toll-like receptor 4 (TLR 4) mRNA expression were tested. DN-initiated fibrotic markers integrin, α-smooth muscle expression and collagen IV and apoptotic protein caspase 3 were tested. DM induced changes starting from the 4th week. At 12th week, early valsartan intervention showed a significant reduction in ANG II, ANGPTL2 and TLR 4 expression and improvement in albuminuria, blood pressure, urinary biomarkers, fibrotic and apoptotic markers, more than the late intervention. Early inhibition of ANG II in diabetes is associated with decrease in ANGPTL2 and TLR 4 proteins and fibrotic changes. This observation helps in understanding DN pathophysiology and its therapeutic approaches.


2011 ◽  
Vol 300 (5) ◽  
pp. F1076-F1088 ◽  
Author(s):  
Xiao C. Li ◽  
Julia L. Cook ◽  
Isabelle Rubera ◽  
Michel Tauc ◽  
Fan Zhang ◽  
...  

The present study tested the hypothesis that intrarenal adenoviral transfer of an intracellular cyan fluorescent fusion of angiotensin II (ECFP/ANG II) selectively in proximal tubules of the kidney increases blood pressure by activating AT1 (AT1a) receptors. Intrarenal transfer of ECFP/ANG II was induced in the superficial cortex of rat and mouse kidneys, and the sodium and glucose cotransporter 2 (sglt2) promoter was used to drive ECFP/ANG II expression selectively in proximal tubules. Intrarenal transfer of ECFP/ANG II induced a time-dependent, proximal tubule-selective expression of ECFP/ANG II in the cortex, which peaked at 2 wk and was sustained for 4 wk. ECFP/ANG II expression was low in the glomeruli and the entire medulla and was absent in the contralateral kidney or extrarenal tissues. At its peak of expression in proximal tubules at day 14, ANG II was increased by twofold in the kidney ( P < 0.01) and more than threefold in proximal tubules ( P < 0.01), but remained unchanged in plasma or urine. Systolic blood pressure was increased in ECFP/ANG II-transferred rats by 28 ± 6 mmHg ( P < 0.01), whereas fractional sodium excretion was decreased by 20% ( P < 0.01) and fractional lithium excretion was reduced by 24% ( P < 0.01). These effects were blocked by losartan and prevented in AT1a knockout mice. Transfer of a scrambled ECFP/ANG IIc had no effects on blood pressure, kidney, and proximal tubule ANG II, or sodium excretion. These results provide evidence that proximal tubule-selective transfer of an intracellular ANG II fusion protein increases blood pressure by activating AT1a receptors and increasing sodium reabsorption in proximal tubules.


1979 ◽  
Vol 57 (s5) ◽  
pp. 123s-125s ◽  
Author(s):  
H. Ibsen ◽  
A. Leth ◽  
A. McNair ◽  
J. Giese

1. Sixteen patients (11 male, five female), median age 41 years, with essential hypertension insufficiently controlled by hydrochlorothiazide (75 mg/day; diastolic blood pressure ≥ 100 mmHg), were studied. 2. Plasma renin concentration [renin], plasma angiotensin II concentration ([ANG II]), plasma volume and exchangeable sodium (NaE) were determined, and a saralasin infusion (5·4 nmol min−1 kg−1) was carried out while the patients were on thiazide alone and, in 14 cases, 3 months after addition of a β-adrenoreceptor blocker (propranolol, six, metoprolol, six, and atenolol, two patients). 3. On thiazide alone, saralasin caused a significant decrease in mean arterial blood pressure in 12 out of 16 patients. The saralasin response was closely related to pre-saralasin plasma [ANG II] (r = −0·73, P &lt; 0·01). Plasma [renin] and [ANG II] were higher than normal in the group as a whole. 4. After addition of a β-adrenoreceptor blocker systolic and diastolic blood pressure decreased from 164/109 mmHg to 136/94 mmHg. Plasma [renin] and [ANG II] decreased by 40 and 58% respectively. At this point, saralasin caused no significant change in mean arterial pressure. No close correlation was found between plasma [renin] or [ANG II] or saralasin response on thiazide treatment and changes in blood pressure during subsequent thiazide/β-adrenoreceptor-blocker treatment. Plasma volume and NaE did not change significantly. 5. In patients with thiazide-induced stimulation of the renin—angiotensin system, addition of a β-adrenoreceptor blocker leads to suppression of the system and, at the same time, ANG II-dependence of blood pressure disappears. This contributes to the antihypertensive effect of β-adrenoreceptor blockers in this particular situation.


1995 ◽  
Vol 79 (5) ◽  
pp. 1657-1667 ◽  
Author(s):  
Y. Moue ◽  
P. G. Smith ◽  
R. L. Clancy ◽  
N. C. Gonzalez

Exposure to hypoxia (2–5 wk) results in systemic hypertension in rats and in humans. The possible mechanism(s) was investigated in rats acclimatized for 3 wk to barometric pressure of approximately 370 Torr (A) and in nonacclimatized littermates (NA) by administration of alpha-adrenergic [phentolamine (PHLM)], angiotensin II (ANG II), and arginine vasopressin (AVP V1) receptor antagonists. Both A and NA rats were studied in hypoxia (inspiratory O2 fraction = 0.10). Baseline mean arterial blood pressure (MABP) was higher in A than in NA rats: 126 +/- 4 vs. 101 +/- 2 mmHg (P < 0.05). Neither ANG II nor AVP V1 receptor antagonist influenced baseline MABP; however, both contributed to MABP recovery after PHLM. After simultaneous blockade of ANG II and AVP V1, PHLM lowered MABP by 65 +/- 2 and 45 +/- 3 mmHg in A and NA rats, respectively (P < 0.05). After combined blockade of the three systems, the smooth muscle relaxant sodium nitroprusside did not further modify MABP, which remained higher in A rats. It is concluded that 1) the hypertension in A rats is partly due to a higher alpha-adrenergic tone, 2) neither ANG II nor AVP contributes to the hypertension, but ANG II and AVP participate in MABP control after PHLM, 3) no other vasoconstrictor agents operate in either group, and 4) the higher MABP in A rats after sodium nitroprusside may reflect additional hypertensive mechanisms.


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