Urinary Angiotensinogen Excretion Research Articles

Elevated urinary angiotensinogen excretion links central and renal hemodynamic alterations

Inappropriate activation of intrarenal renin–angiotensin system (RAS) may contribute to the pathogenesis of cardio-renal syndrome (CRS). We aimed to examine the cross-sectional associations of urinary angiotensinogen (AGT) excretion, a biomarker of intrarenal RAS activity, with central (aortic) and renal hemodynamic parameters in middle-aged and older adults, including patients with chronic kidney disease. Aortic and renal hemodynamic parameters were measured using applanation tonometry and duplex ultrasonography in 282 participants. Urinary AGT, liver-type fatty acid-binding protein (L-FABP), and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured for each participant. Multiple linear regression analyses demonstrated that urinary AGT levels were associated with aortic blood pressures, pulsatile measures of renal blood flow, plasma NT-proBNP and urinary L-FABP levels after adjusting for potential covariates, including age, sex, body mass index, estimated glomerular filtration rate (GFR), and medication use. Additionally, when classified based on GFR stages and urinary AGT levels, plasma NT-proBNP and urinary L-FABP levels increased in participants with lower GFR and higher AGT groups. Our findings suggest that urinary AGT excretion is a shared determinant of central (aortic) and renal hemodynamics in middle-aged and older adults, providing clinical evidence for the potential role of intrarenal RAS activity in the development of CRS.

Augmented Urinary Excretion of Angiotensinogen Precedes Albuminuria in Human Young Adults with Overweight and Mice with High Fat Diet‐Induced Type 2 Diabetes

Obesity is linked to the development of hypertension and type 2 diabetes (T2D) and both causing chronic kidney disease (CKD). Increased body mass index (BMI) and high fat diet (HFD) contribute to activation systemic renin angiotensin system (RAS). In addition, activation of intrarenal and intratubular RAS has been associated with increased pressure (BP), CKD, and augmentation of urinary excretion of angiotensinogen (uAGT) during T2D. However, whether augmentation of uAGT reflect intrarenal/intratububular RAS activation in subjects with overweight, remains unclear. Here, we tested the hypothesis that increases in uAGT precedes renal dysfunction in mice and human subjects with overweight,MethodsC57BL/6 mice (N = 10) were fed either a normal fat diet (NFD) or HFD (45% Kcal from fat) for 28 weeks. During this period, metabolic phenotype along with urinary albumin, creatinine, reactive oxygen species (ROS) and AGT, were measured every 4 weeks. In addition, for evidence in humans (age 19‐22 years‐old), 11 individuals with overweight and 17 individuals with normal weight, were studied. In these subjects, anthropometric parameters, systolic and diastolic BP, fasting blood glucose (FBG), and urinary mRNA levels of AGT and kidney injury markers IL‐18 and connecting tissue growth factor, were determined. Patients with history of cardiac or cerebrovascular events and endocrine diseases, anti‐hypertensive treatment (ACE inhibitors, ARBs) and/or anti‐diabetic drugs, were excludedResultsIn mice with metabolic alterations overtime, systolic BP significantly increased after 18 weeks in HFD but not NFD mice. Intrarenal ROS increased in HFD mice. These changes paralleled the augmentation uAGT excretion, which occurred in the absence of overt albuminuria. In human subjects with overweight, systolic and diastolic BP, urinary transcripts levels of AGT, renin, and injury markers IL‐18 and CTGF were increased as compared to normal weight individuals. However, no significant changes were observed in proteinuria or albuminuria.ConclusionsOur results indicate that augmentation of uAGT precedes albuminuria in young human adults with overweight and mice during the development of HFD‐induced T2D. These findings emphasize the relevance of uAGT and indicator of intrarenal/intratubular RAS activations and its potential as early biomarker of kidney injury during metabolic diseases as obesity and diabetes.

Reduced urinary angiotensinogen excretion in preeclampsia.

This study evaluated urinary angiotensinogen in preeclampsia. Normal pregnant (n=57) and preeclamptic patients (n=31); Normal pregnant (n=10) and preeclamptic rats (n=10) were studied. Urinary angiotensinogen and plasma angiotensin II were assayed by enzyme-linked immunosorbent assay (ELISA). Urinary angiotensinogen in preeclampsia patients (2.0±1.1ng/mg creatinine) was suppressed (*p<0.05) compared to normal pregnant (2.7±1.5ng/mg creatinine). Plasma angiotensin II in preeclampsia patients (preeclampsia: 36.2±7; normal pregnant: 48.1±5fmol/mL) was lower. The similar result was observed in preeclampsia rat model. The reduced urinary excretion of angiotensinogen was both in human preeclampsia patients and rat model of preeclampsia.

Effects of Exercise Training on the Renin-Angiotensin System in the Kidneys of Dahl Salt-Sensitive Rats.

Exercise training (Ex) has antihypertensive and renal protective effects; however, the precise mechanisms remain unclear. The renal renin-angiotensin system (RAS) plays a vital role in renal function and pathology. Therefore, we investigated the effects of Ex on the renal RAS components in Dahl salt-sensitive (Dahl-S) rats. Male Dahl-S rats were divided into four groups: normal salt diet + sedentary, normal salt diet + Ex, high-salt diet (HS, 8% NaCl) + sedentary, and HS + Ex. Treadmill running was performed for 8 wk in the Ex groups. Ex attenuated the HS-induced renal dysfunction and glomerular injury without causing blood pressure alterations. HS increased urinary excretion of both total and intact angiotensinogen. Ex decreased the HS-induced increased urinary excretion of total angiotensinogen. However, it did not change the HS-induced urinary excretion of intact angiotensinogen, indicating reduced intact angiotensinogen cleaving. Ex restored the HS-induced increased angiotensinogen and angiotensin II type 1 receptor expressions in the outer medulla and the HS-induced increased angiotensin-converting enzyme expression in the cortex. Ex restored the HS-induced decreased renin expression in the cortex and outer medulla, and the HS-induced decreased angiotensin-converting enzyme 2, angiotensin II type 2 receptor, and Mas receptor expressions in the outer medulla. Ex attenuates HS-induced renal dysfunction, glomerular injury, and renal RAS dysregulation in Dahl-S rats.

Biomarkers for early diagnosis of diabetic kidney disease: still a long way to go.

Biomarkers for early diagnosis of diabetic kidney disease: still a long way to go.

Urinary excretion of renin and angiotensinogen in hypertensive children and adolescents.

IntroductionIn recent years hypertension has become an emerging condition in the young population. It has been proposed that the renin–angiotensin system plays an important role in regulation of blood pressure. We assessed whether activation of the intrarenal renin-angiotensin system occurs in hypertensive children and adolescents and what better reflects its activity: urine angiotensinogen (AGT) or urine renin (REN).Material and methodsThe study was conducted on a sample of 58 subjects with primary hypertension (HT) and 29 normotensive children and adolescents. We measured urine REN and AGT excretion and assessed the values in relation to blood pressure (BP) and other clinical parameters. Both REN and AGT values were calculated by urine creatinine: REN/cr. and AGT/cr., respectively.ResultsWe observed higher urine REN/cr. values in hypertensive subjects in comparison to the reference group (6.99 vs. 2.93, p = 0.003). Hypertensive participants showed positive correlations between urine REN/cr. and diastolic 24-hour BP (r = 0.42, p = 0.002) as well as between urine REN/cr. and urine AGT/cr. (r = 0.266, p = 0.044, respectively).ConclusionsIncreased urine REN/cr. in hypertensive children and adolescents and its positive correlation with BP may indicate its important role in the pathogenesis of HT. Perhaps urine REN/cr. could be a marker of intrarenal renin-angiotensin system activity. Nevertheless, further research should be undertaken to confirm this observation.

Baseline Urinary Angiotensinogen Excretion Predicts Deterioration of the Kidney Function in Patients with Chronic Kidney Disease.

Objective The intrarenal renin-angiotensin system (RAS) is activated in patients with chronic kidney disease (CKD), and urinary angiotensinogen (AGT) levels, a surrogate marker of the intrarenal RAS activation, are associated with blood pressure (BP) and urinary albumin excretion. In addition, it has been shown that changes in urinary AGT levels correlate with annual changes in the estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes and that elevated levels of urinary AGT in type 2 diabetic patients with albuminuria are a high-risk factor for worsening renal and cardiovascular complications. However, whether or not baseline urinary AGT levels predict deterioration of the kidney function in all patients with CKD is unclear. Methods We recruited 62 patients with CKD whose eGFR was ＞15 mL/min/1.73 m2. We performed 24-hour ambulatory BP monitoring at 30-min intervals and daily urinary collection to examine the urinary AGT levels and albumin excretion and measured the levels of plasma angiotensin II (Ang II), a surrogate marker of circulating RAS. In addition, annual changes in the eGFR were followed up for 3.4±1.5 years. Results Annual changes in the eGFR were significantly and negatively associated with urinary AGT levels (r=-0.31, p=0.015) as well as the age, systolic BP, and urinary albumin levels. In contrast, annual changes in the eGFR were not correlated with plasma Ang II levels. Furthermore, when dividing patients into quartiles according to urinary AGT levels, patients with the highest urinary AGT levels showed a progressive decline in the eGFR. Conclusion These results suggest that elevated baseline urinary AGT levels can predict renal dysfunction in patients with CKD.

Effect of sodium bicarbonate supplementation on the renin-angiotensin system in patients with chronic kidney disease and acidosis: a randomized clinical trial

BackgroundAcidosis-induced kidney injury is mediated by the intrarenal renin-angiotensin system, for which urinary renin is a potential marker. Therefore, we hypothesized that sodium bicarbonate supplementation reduces urinary renin excretion in patients with chronic kidney disease (CKD) and metabolic acidosis.MethodsPatients with CKD stage G4 and plasma bicarbonate 15–24 mmol/l were randomized to receive sodium bicarbonate (3 × 1000 mg/day, ~ 0.5 mEq/kg), sodium chloride (2 × 1,00 mg/day), or no treatment for 4 weeks (n = 15/arm). The effects on urinary renin excretion (primary outcome), other plasma and urine parameters of the renin-angiotensin system, endothelin-1, and proteinuria were analyzed.ResultsForty-five patients were included (62 ± 15 years, eGFR 21 ± 5 ml/min/1.73m2, plasma bicarbonate 21.7 ± 3.3 mmol/l). Sodium bicarbonate supplementation increased plasma bicarbonate (20.8 to 23.8 mmol/l) and reduced urinary ammonium excretion (15 to 8 mmol/day, both P < 0.05). Furthermore, a trend towards lower plasma aldosterone (291 to 204 ng/L, P = 0.07) and potassium (5.1 to 4.8 mmol/l, P = 0.06) was observed in patients receiving sodium bicarbonate. Sodium bicarbonate did not significantly change the urinary excretion of renin, angiotensinogen, aldosterone, endothelin-1, albumin, or α1-microglobulin. Sodium chloride supplementation reduced plasma renin (166 to 122 ng/L), and increased the urinary excretions of angiotensinogen, albumin, and α1-microglobulin (all P < 0.05).ConclusionsDespite correction of acidosis and reduction in urinary ammonium excretion, sodium bicarbonate supplementation did not improve urinary markers of the renin-angiotensin system, endothelin-1, or proteinuria. Possible explanations include bicarbonate dose, short treatment time, or the inability of urinary renin to reflect intrarenal renin-angiotensin system activity.Graphic abstract

High blood pressure induced by vitamin D deficiency is associated with renal overexpression and hyperphosphorylation of Na+-K+-2Cl- cotransporter type 2.

Clinical and epidemiological studies have suggested a correlation between vitamin D deficiency (VDD) and high blood pressure (BP). This study aimed to test the hypothesis that high BP induced by VDD is associated with altered expression and covalent modification of apical sodium transporters along the nephron. The contributions of the intrarenal renin-angiotensin system (RAS) and oxidative stress were also investigated. Male Wistar rats were fed a vitamin D-free (n = 26) or standard diet (n = 25) for 30 days. BP was recorded using noninvasive and invasive procedures. The expression levels of total and phosphorylated apical sodium transporters in rat renal cortex and medulla were evaluated by immunoblotting. Intrarenal RAS components were assessed by immunoblotting and ELISA. Renal oxidative stress was analyzed by measuring the concentrations of thiobarbituric acid reactive substances and reduced glutathione. Higher BP levels in VDD rats than controls were accompanied by overexpression and hyperphosphorylation of renal cortical and medullary Na+-K+-2Cl- cotransporter type 2, enhanced levels of phosphorylated Na+/H+ exchanger type 3, and reduced expression levels of total and phosphorylated Na+/Cl- cotransporter. Changes in intrarenal RAS induced by VDD vs. controls included the marked elevation of medullary renin expression, higher expression of cortical angiotensinogen, higher urinary angiotensinogen excretion, and higher cortical and medullary angiotensin II content. VDD rats displayed higher thiobarbituric acid reactive substances/glutathione ratios in the renal cortex and medulla than controls. These results suggest that the molecular mechanisms underlying the effects of VDD on BP may include the upregulation of Na+-K+-2Cl- cotransporter type 2 and activation of intrarenal RAS and oxidative stress.

Effect of urinary angiotensinogen and high-salt diet on blood pressure in patients with chronic kidney disease: results from the Korean Cohort Study for Outcome in Patients with Chronic Kidney Disease (KNOW-CKD).

Background/AimsThis study aimed to investigate whether urinary angiotensinogen (UAGT) excretion was associated with elevated blood pressure in patients with chronic kidney disease (CKD) and to evaluate the relationship among blood pressure, intra-renal renin-angiotensin system (RAS) activity, and dietary sodium in patients with CKD.MethodsParticipants from the Korean Cohort Study for Outcome in Patients with Chronic Kidney Disease (KNOW-CKD) were included. Of the total cohort of 2,238 individuals with CKD, we included 1,955 participants who underwent complete 24-hour urinary sodium (24-hour UNa) analysis. They were categorized into three groups according to three tertiles of their 24-hour UNa, reflecting daily salt intake. To measure intra-renal RAS activity, the UAGT excretion was assayed with an enzyme-linked immunosorbent assay.ResultsElevated 24-hour UNa levels, logarithm of UAGT-to-creatinine ratio (UAGT/Cr), increased waist-to-hip ratio, and decreased estimated glomerular filtration rate were the risk factors for increased systolic blood pressure. Systolic blood pressure showed a positive correlation with 24-hour UNa levels and logarithm of UAGT/Cr.ConclusionsUAGT and urinary sodium excretion are independent determinants of systolic blood pressure in patients with CKD. These findings suggest that increased systolic blood pressure in CKD patients is associated with both increased dietary sodium levels and intra-renal RAS activity. The risk of elevated systolic blood pressure in the 3rd tertile of both the UAGT/Cr and 24-hour UNa groups was about 2.3 times higher than that in the reference group.

Abstract P031: Reduced Augmentation Of The Intrarenal Renin-angiotensin System (ras), Lower Systolic Blood Pressure, And Preserved Renal Function In Female Compared To Male Rats With Unilateral Renal Artery Stenosis

Despite growing evidence of sex differences in the progression of hypertension, there are no guidelines that differentiate treatment between men and women. Intrarenal renin-angiotensin system (RAS) activation and tissue injury in 2-kidney, 1-clip (2K1C) hypertensive rats have been characterized in previous studies of male but not female rats. To evaluate possible sex differences in response to renovascular hypertension, urinary angiotensinogen (uAGT) excretion, systolic blood pressure (BP), urinary protein excretion, and renal function were assessed in female rats.Female (n=8) and male (n=6) rats underwent placement of a 0.2 mm clip on the left renal artery to simulate unilateral renal artery stenosis. BP was measured by tail-cuff plethysmography, and clearance studies were conducted in anesthetized rats to assess renal function. Urine protein concentration was determined by pyrogallol red method. uAGT was measured by ELISA as an index of intrarenal RAS activity. Systolic BP increased from 120±1 to 176±8 mmHg, and urinary protein excretion reached 20.2±5.6 mg/day in female rats. Although uAGT excretion increased from 13.2±7.7 ng/day to 74.1±29.9 ng/day in female rats, male rats had a significantly higher uAGT excretion of 1572.6±750 ng/day. Nonclipped kidneys exhibited more uAGT excretion compared to clipped kidneys, consistent with previous findings in males. Although 2K1C female rats demonstrate significantly lower renal function than sham females, they show more preserved renal function than male rats. Female rats also demonstrate significantly lower increases in systolic BP and urinary protein excretion compared to male rats. The data support substantial sex-dependent differences in renal responses to unilateral renal artery stenosis. The results show substantial increases in systolic BP, uAGT, and urinary protein excretion and decreased renal function after renal artery clipping in females, but the magnitude of the changes is markedly lower than in males. Nonclipped kidneys of both sexes exhibit greater uAGT excretion than clipped kidneys. Notably, females show less augmentation of the intrarenal RAS compared to male rats in renovascular hypertension.

Sex Differences in Urinary Angiotensinogen (uAGT) Excretion, Renal Function, and Systolic Blood Pressure in 2‐Kidney, 1‐Clip Hypertensive Rats

Intrarenal renin‐angiotensin system (RAS) activation and tissue injury in nonclipped kidneys of 2‐kidney, 1‐clip (2K1C) hypertensive rats have been characterized in previous studies of male but not female rats. To evaluate possible sex differences in response to renovascular hypertension, urinary angiotensinogen (uAGT) excretion, arterial blood pressure, urinary protein excretion, and renal function were assessed in 2K1C female rats.Female (n=8) and male (n=6) Sprague Dawley rats underwent placement of a 0.2 mm silver clip on the left renal artery to simulate unilateral renal artery stenosis. BP was measured by tail‐cuff plethysmography, and 24‐hour urine volume and water intake were monitored via metabolic cages over 21 days. After this period, renal clearance studies were conducted in anesthetized rats, and urine was collected from each kidney separately over 30 minute intervals. Urine protein concentration was determined by pyrogallol red method, and uAGT was measured by ELISA as an index of intrarenal RAS activity. Inulin and PAH concentrations were measured by spectrophotometry for calculation of glomerular filtration rate (GFR), renal plasma flow (RPF), and renal blood flow (RBF).21 days after renal artery clipping, systolic BP had risen to 176±8 mmHg from a baseline pressure of 120±1 mmHg, and urinary protein excretion increased to 20±5 mg/day in females. uAGT excretion was significantly increased from the baseline of 13 ng/day to 74 ng/day (507±127% increase). The nonclipped kidney showed 90±29% higher uAGT excretion compared to the clipped kidney, consistent with our previous findings in males. GFR and RPF were higher in nonclipped kidneys than in clipped kidneys but were greater than in corresponding measurements in males. GFR, RPF, and RBF were significantly higher in control rats compared to both clipped and nonclipped kidneys. Male rats showed significantly higher increases in uAGT, BP, and protein excretion.The present study demonstrates that BP, uAGT, and urinary protein excretion substantially increase after renal artery clipping in females, but the magnitude of the changes is markedly lower than in males. Additionally, the nonclipped kidney showed higher uAGT excretion compared to the clipped kidney. Although GFR, RPF, and RBF were significantly lower than control values for both clipped and nonclipped kidneys, these values were higher for females than males. These results demonstrated that female rats may be protected against AngII‐mediated renal injury and hypertension.Support or Funding InformationSupported by the ASPiRE Program at Tulane Univ Sch Medicine, New Orleans, LA and the Warren R. Bourgeois III, MD and Usha Ramadhyani Bourgeois, MD Student Research Endowed Fund at Tulane Univ Sch Medicine, New Orleans, LA

Urinary angiotensinogen increases in the absence of overt renal injury in high fat diet-induced type 2 diabetic mice

Aim of the StudyDuring type 2 diabetes (T2D) and hypertension there is stimulation of renal proximal tubule angiotensinogen (AGT), but whether urinary excretion of AGT (uAGT) is an indicator of glomerular damage or intrarenal RAS activation is unclear. We tested the hypothesis that elevations in uAGT can be detected in the absence of albuminuria in a mouse model of T2D. MethodsMale C57BL/6 mice (N = 10) were fed a high fat (HFD; 45% Kcal from fat) for 28 weeks, and the metabolic phenotype including body weight, blood pressures, glucose, insulin, ippGTT, HOMA-IR, and cholesterol was examined. In addition, kidney Ang II content and reactive oxygen species (ROS) was measured along with urinary albumin, creatinine, Ang II, and AGT. ResultsAll parameters consistent with T2D were present in mice after 12–14 weeks on the HFD. Systolic BP increased after 18 weeks in HFD but not NFD mice. Intrarenal ROS and Ang II concentrations were also increased in HFD mice. Remarkably, these changes paralleled the augmentation uAGT excretion (3.66 ± 0.50 vs. 0.92 ± 0.13 ng/mg by week 29; P < 0.01), which occurred in the absence of overt albuminuria. ConclusionsIn HFD-induced T2D mice, increases in uAGT occur in the absence of overt renal injury, indicating that this biomarker accurately detects early intrarenal RAS activation.

The pivotal role of melatonin in ameliorating chronic kidney disease by suppression of the renin–angiotensin system in the kidney

Melatonin is a hormone produced by the pineal gland, predominantly at night, and plays a pivotal role in regulating the circadian rhythm as well as a variety of biological functions, including anti-inflammation, anti-oxidation, inhibition of sympathetic nerve activity, and preservation of endothelial cell function. The intrarenal renin-angiotensin system (RAS) is one of the most important contributors in the pathophysiology of chronic kidney disease (CKD) and hypertension, independent of the circulating RAS, due to sodium reabsorption and inflammation and fibrosis in the kidney. However, the relationship between melatonin secretion and intrarenal RAS activation has remained unknown. It has been recently shown that impaired nighttime melatonin secretion is associated with nighttime urinary angiotensinogen excretion, a surrogate marker of intrarenal RAS activation and renal damage in patients with CKD. Moreover, it has also been indicated that melatonin administered exogenously exercises antioxidant effects that ameliorate intrarenal RAS activation and renal injury in chronic progressive CKD animal models. As a result, the new roles of melatonin in suppressing RAS in the kidney via amelioration of reactive oxygen species have been clarified. Therefore, we review the relationship between melatonin and intrarenal RAS activation and indicate the possibility of a new strategy to suppress CKD, which is a risk factor for cardiovascular and end-stage renal diseases.

Enhanced angiotensinogen expression in neonates during kidney development

We recently demonstrated that preterm neonates have higher urinary angiotensinogen (AGT) levels than full-term neonates. Here, we tested the hypothesis that enhanced neonatal AGT expression is associated with intrarenal renin-angiotensin system (RAS) status during kidney development. We prospectively recruited neonates born at our hospital and healthy children with minor glomerular abnormalities between April 2013 and March 2017. We measured neonatal plasma and urinary AGT levels at birth and 1 year later and assessed renal AGT expression in kidney tissues from neonates and healthy children using immunohistochemical (IHC) analysis. Fifty-four neonates and eight children were enrolled. Although there were no changes in plasma AGT levels, urinary AGT levels were significantly decreased 1 year after birth. Urinary AGT levels at birth were inversely correlated with gestational age, and urinary AGT levels at birth and 1 year later were inversely correlated with estimated glomerular filtration rate 1 year after birth. IHC analysis showed that renal AGT expression in neonates was higher than that in healthy children and inversely correlated with gestational age. Enhanced AGT expression and urinary AGT excretion may reflect intrarenal RAS activation associated with kidney development in utero.

The Intrarenal Renin-angiotensin System Is Activated Immediately after Kidney Donation in Kidney Transplant Donors.

Objective The intrarenal renin-angiotensin system (RAS) is activated in clinical settings, such as chronic kidney disease (CKD), as well as in CKD animal models, and kidney transplant donors have a greater risk of end-stage renal disease than healthy controls. However, whether or not the intrarenal RAS is activated immediately after kidney donation in kidney transplant donors is unclear, and the mechanism underlying intrarenal RAS activation is unknown. Methods We investigated 10 kidney transplant donors (4 men and 6 women, 58.6±9.0 years of age). Their blood pressure (BP), estimated glomerular filtration rate (eGFR), plasma angiotensinogen (AGT) and plasma angiotensin II (AngII) levels (which reflect circulating RAS activation), urinary albumin excretion, and urinary AGT excretion (which reflects intrarenal RAS activation) were evaluated before kidney donation (-1.2±0.40 days) and after kidney donation (7.5±1.7 days). Results The renal function after kidney donation was significantly lower than before donation. There were no significant differences in the BP during 24-h ambulatory BP monitoring, plasma AngII levels, or urinary albumin excretion after kidney donation. In contrast, the levels of plasma AGT and urinary AGT excretion were significantly increased after kidney donation. The urinary AGT excretion after kidney donation did not show a significant relationship with the systolic BP, plasma AGT, plasma AngII, or urinary albumin excretion. In addition, the percentage change in urinary AGT excretion after kidney donation was not associated with the percentage change in other clinical parameters. Conclusion The intrarenal RAS is activated in kidney transplant donors immediately after kidney donation, independent of the systemic BP and filtration of increased plasma AGT, due to augmented inflammation.

Abstract P380: Inverse Circadian Pattern in the Renal Generation of Tumor Necrosis Factor-Alpha (TNFå) and Angiotensinogen (AGT) in Salt-Sensitive Hypertension (SSH) Induced by Angiotensin II (AngII) in Mice

Individuals with SSH show a non-dipping blood pressure (BP) during the inactive night period, a phenomenon which is significantly associated with enhanced cardiovascular morbidity and mortality. However, the pathophysiological mechanism for this phenomenon is not yet clearly understood. Chronic AngII administration in mice (reversed circadian rhythm) induced SSH with an increase in intra-renal AGT formation, a response that was exaggerated in TNFα receptor type 1 (TNFR1) knockout mice, indicating that renal AGT formation is suppressed by TNFR1 activation by TNFα. The present study examined the hypothesis that AngII-induced TNFα formation follows a circadian pattern with increases during the active period compared to the inactive period, that facilitates less AGT formation during the active period. Experiments were performed in mice chronically treated with or without AngII (25 ng/min; osmotic mini-pump) + high salt (4% NaCl) intake for 4 weeks that increased BP from 90±2 to 108±3 mmHg (tail-cuff method). Circadian rhythm in urinary parameters was assessed by 12 hour collections of urine using metabolic cages during the active night period (7PM to 7AM) and the inactive day period (7 AM to 7 PM). In normal mice (n=6), urinary excretion of TNFα (uTNFα) was higher (0.5±0.2 vs 0.13±0.08 pg/hour) but urinary excretion of AGT (uAGT) was lower (0.28±0.18 vs 0.46±0.14 ng/hour) during the active period compared to that during the inactive period. This inverse relationship between uTNFα and uAGT was exaggerated in AngII+HS treated mice (n=6). From the baseline (0 week) to the 2nd and 4 th week period, there were marked incremental changes in uTNFα during active periods (0.68±0.20 to 14.2±5.4 and 44.6±14.6 pg/hour) which were less during inactive periods (0.73±0.48 to 10.3±3.3 and 12.1±4.7 pg/hour). Interestingly, uAGT changed minimally during active periods (0.21±0.14 to 0.05±0.04 and 1.42±0.97 ng/hour) but increased significantly during inactive periods (0.32±0.14 to 1.57±0.71 and 3.98±1.67 ng/hour). These data suggest that an increase in TNFα generation suppresses intra-renal AGT formation during active periods but this phenomenon is inversed during inactive periods. The increase in AGT during the inactive period could lead to a non-dipping BP pattern in SSH.

Abstract P306: Preterm Birth is Associated with Increased Blood Pressure and Increased Urinary Angiotensinogen in Young Adults

Introduction: Cardiovascular disease (CVD) is the leading cause of mortality and hypertension (HTN) is a major risk factor for CVD. Preterm birth is an emerging risk factor for both CVD and HTN, but the underlying mechanisms are poorly described. The renin-angiotensin system (RAS) plays a key role in HTN and CVD, and adolescents born preterm have higher blood pressure (BP) with a shift in the balance of the classical and alternative pathways of the RAS exhibited as increased angiotensin II and reduced angiotensin-(1-7) as compared to term-born adolescents. Although numerous factors influence the expression of angiotensins, the precursor protein angiotensinogen in the kidney is implicated in the development of HTN and CVD and may contribute to higher angiotensin II. As the status of renal angiotensinogen in individuals born preterm is unknown, we hypothesized that urinary angiotensinogen is increased in young adults born preterm as compared to their term-born peers. Methods: We compared urinary excretion of angiotensinogen corrected for urine creatinine and systolic and diastolic BP in 142 young adults (mean age 19.9 years) born preterm with very low birth weight (&lt;1500 g) to 32 young adults born term using Wilcoxon Rank-Sum test and t-test. We used generalized linear models to compare the ln(x) urinary angiotensinogen between the preterm and term groups adjusted for the potentially confounding factors race, maternal hypertensive pregnancy, and maternal smoking during pregnancy. Results: Compared to term, subjects born preterm had higher median urinary angiotensinogen (0.02 μg/g, IQR 0.01 to 0.04 vs. 0.01 μg/g, IQR 0.004 to 0.01, p &lt; 0.001) and higher mean systolic BP (111 mmHg, SD 11 vs. 106 mmHg, SD 10, p = 0.03). On crude and adjusted analyses urinary angiotensinogen was associated positively with preterm birth (crude β : 0.82, 95% CI 0.47 to 1.16; adjusted β : 0.79, 95% CI 0.39 to 1.18). Discussion: In addition to higher BP, young adults born preterm demonstrated increased urinary angiotensinogen as compared to their term-born peers. Preterm birth may induce programming of the renal RAS leading to higher angiotensinogen and a higher angiotensin-to-angiotensin-(1-7) ratio, potentially contributing to the increased risk of HTN in individuals born preterm.

Correlation between the 24-h urinary angiotensinogen or aldosterone level and muscle mass: Japan shimanami health promoting program study

Our previous report indicated that sarcopenia is associated with arterial stiffness and cardiovascular death. The renin-angiotensin system (RAS) plays an important role in cardiovascular disease and its activation may be correlated with sarcopenia according to basic research. However, few clinical studies have assessed the correlation between skeletal muscle loss and RAS component concentrations in healthy subjects. The purpose of this study was to investigate the relationships between the excretion of angiotensinogen (AGT) and aldosterone (Ald) in 24-h urine samples and clinical and sarcopenic indices. A total of 344 people participated in a voluntary medical check-up program, "Anti-Aging Doc", and underwent measurement of their sarcopenia-related indices. Urine samples were collected for 24-h within 8 weeks after a medical check-up using a partition cup and a proportional sampling method. Urine AGT and Ald levels were evaluated by enzyme-linked immunosorbent assay (ELISA). After compensating for possible confounding parameters, including baPWV, the 24-h urinary excretion of AGT was independently and negatively associated with the thigh muscle cross-sectional area. On the other hand, urinary Ald excretion was not associated with sarcopenia-related indices after compensation, even though it showed a modest but significantly positive association with sarcopenic indices in single regression analysis. Urinary AGT was related to sarcopenic indices and may be involved in the pathogenesis of sarcopenia. On the other hand, urinary Ald was not related to sarcopenic indices when considering other risk factors.

Night-time activation of the intrarenal renin-angiotensin system due to nocturnal hypertension is associated with renal arteriosclerosis in normotensive IgA nephropathy patients.

Intrarenal renin-angiotensin system (RAS) activation plays an important role in the development of hypertension and renal damage. However, the association between daytime and night-time intrarenal RAS activation and renal structural damage in normotensive IgA nephropathy patients is unclear. We investigated the relationships between urinary angiotensinogen (U-AGT) excretion, which reflects intrarenal RAS activity, and renal structural damage (i.e., endocapillary and mesangial cell hypercellularity, arteriolar hyalinosis and arteriosclerosis levels, and global glomerulosclerosis and tubulointerstitial fibrosis percentages) in 27 normotensive IgA nephropathy patients (age 39.2 ± 13.6 years, 10 men and 17 women, estimated glomerular filtration rate (eGFR) 74.0 ± 17.3 ml/min/1.73 m2, urinary protein excretion 0.58 ± 0.50 g/day, and U-AGT excretion 64.9 ± 100.6 μg/day). The arteriosclerosis level had a significant positive association with the daytime and night-time U-AGT excretion levels. By contrast, the endocapillary and mesangial cell hypercellularity and arteriolar hyalinosis levels and global glomerulosclerosis and tubulointerstitial fibrosis percentages did not correlate with the daytime and night-time U-AGT excretion levels. The daytime and night-time U-AGT excretion levels were higher in patients with arteriosclerotic changes than in patients without these changes. Multiple linear regression analysis revealed that the arteriosclerosis levels had a significant positive association with the U-AGT excretion levels at night after adjusting for age, sex, body mass index, and the eGFR. However, when diastolic BP was added as an independent variable, the relationship between U-AGT excretion and arteriosclerosis at night disappeared. In normotensive IgA nephropathy patients, intrarenal RAS activation at night due to nocturnal hypertension may be associated with arteriosclerosis.