Renin-angiotensin System Levels Research Articles

Renin and angiotensin (1-7) offer predictive value in pediatric sepsis: findings from prospective observational cohorts.

Pediatric sepsis is a common and complex syndrome characterized by a dysregulated immune response to infection. Aberrations in the renin-angiotensin system (RAS) are factors in several infections of adults. However, the precise impact of RAS dysregulation in pediatric sepsis remains unclear. Serum samples were collected from a derivation cohort (58 patients with sepsis, 14 critically ill control subjects, and 37 healthy controls) and validation cohort (50 patients with sepsis, 37 critically ill control subjects, and 46 healthy controls). Serum RAS levels on day of PICU admission were determined and compared with survival status and organ dysfunction. In the derivation cohort, the serum renin concentration was significantly higher in patients with sepsis (3678 ± 4746) than that in healthy controls(635.6 ± 199.8) (p < 0.0001). Meanwhile, the serum angiotensin (1-7) was significantly lower in patients with sepsis (89.7 ± 59.7) compared to that in healthy controls(131.4 ± 66.4) (p < 0.01). These trends were confirmed in a validation cohort. Non-survivors had higher levels of renin (8207 ± 7903) compared to survivors (2433 ± 3193) (p = 0.0001) and lower levels of angiotensin (1-7) (60.9 ± 51.1) compared to survivors (104.0 ± 85.1) (p < 0.05). A combination of renin, angiotensin (1-7) and procalcitonin achieved a model for diagnosis with an area under the receiver operating curve (AUROC) of 0.87 (95% CI: 0.81-0.92). Circulating renin and angiotensin (1-7) have predictive value in pediatric sepsis.

Angiotensinergic effect of β-Caryophyllene on Lipopolysaccharide- induced systemic inflammation

Renin-Angiotensin System (RAS) is a peptidergic system, canonically known for its role in blood pressure regulation. Furthermore, a non-canonical RAS regulates pathophysiological phenomena, such as inflammation since it consists of two main axes: the pro-inflammatory renin/(pro)renin receptor ((P)RR) axis, and the anti-inflammatory angiotensin-converting enzyme 2 (ACE2)/Angiotensin-(1–7) (Ang-(1–7))/Mas Receptor (MasR) axis. Few phytochemicals have shown to exert angiotensinergic and anti-inflammatory effects through some of these axes; nevertheless, anti-inflammatory drugs, such as phytocannabinoids have not been studied regarding this subject. Among phytocannabinoids, β-Caryophyllene stands out as a dietary phytocannabinoid with antiphlogistic activity that possess a unique sesquiterpenoid structure. Although its cannabinergic effect has been studied, its angiotensinergic effect reminds underexplored. This study aims to explore the angiotensinergic effect of β-Caryophyllene on inflammation and stress at a systemic level. After intranasal Lipopolysaccharide (LPS) installation and oral treatment with β-Caryophyllene, the concentration and activity of key RAS elements in the serum, such as Renin, ACE2 and Ang-(1–7), along with the stress hormone corticosterone and pro/anti-inflammatory cytokines, were measured in mice serum. The results show that β-Caryophyllene treatment modified RAS levels by increasing Renin and Ang-(1–7), alongside the reduction of pro-inflammatory cytokines and corticosterone levels. These results indicate that β-Caryophyllene exhibits angiotensinergic activity in favor of anti-inflammation.

Human soluble prorenin receptor expressed in mouse renal collecting duct shows sex-specific effect on cardiorenal function.

Soluble prorenin receptor (sPRR), a component of the renin-angiotensin system (RAS), has been identified as a plasma biomarker for hypertension and cardiovascular diseases in humans. Despite studies showing that sPRR in the kidney is produced by tubular cells in the renal collecting duct (CD), its biological actions modulating cardiorenal function in physiological conditions remain unknown. Therefore, the objective of our study was to investigate whether CD-derived human sPRR (HsPRR) expression influences cardiorenal function and examine sex and circadian differences. Thus, we investigated the status of the intrarenal RAS, water and electrolyte balance, renal filtration capacity, and blood pressure (BP) regulation in CD-HsPRR and control (CTL) mice. CD-HsPRR mice were generated by breeding human sPRR-Myc-tag mice with Hoxb7/Cre mice. Renal sPRR expression increased in CD-HsPRR mice, but circulating sPRR and RAS levels were unchanged compared with CTL mice. Only female littermates expressing CD-HsPRR showed 1) increased 24-h BP, 2) an impaired BP response to an acute dose of losartan and attenuated angiotensin II (ANG II)-induced hypertension, 3) reduced angiotensin-converting enzyme activity and ANG II content in the renal cortex, and 4) decreased glomerular filtration rate, with no changes in natriuresis and kaliuresis despite upregulation of the β-subunit of the epithelial Na+ channel in the renal cortex. These cardiorenal alterations were displayed only during the active phase of the day. Taken together, these data suggest that HsPRR could interact with ANG II type 1 receptors mediating sex-specific, ANG II-independent renal dysfunction and a prohypertensive phenotype in a sex-specific manner.NEW & NOTEWORTHY We successfully generated a humanized mouse model that expresses human sPRR in the collecting duct. Collecting duct-derived human sPRR did not change circulating sPRR and RAS levels but increased daytime BP in female mice while showing an attenuated angiotensin II-dependent pressor response. These findings may aid in elucidating the mechanisms by which women show uncontrolled BP in response to antihypertensive treatments targeting the RAS, improving approaches to reduce uncontrolled BP and chronic kidney disease incidences in women.

Aerobic training-mediated DNA hypermethylation of Agtr1a and Mas1 genes ameliorate mesenteric arterial function in spontaneously hypertensive rats.

The imbalance of vasoconstrictor and vasodilator axes of the renin-angiotensin system (RAS) is observed in hypertension. Exercise regulates RAS level and improves vascular function. This study focused on the contribution of RAS axes in vascular function of mesenteric arteries and exercise-induced DNA methylation of the Agtr1a (AT1aR) and Mas1 (MasR) genes in hypertension. Spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats were randomized into exercise or sedentary group. Levels of plasma RAS components, vascular tone, and DNA methylation markers were measured. Blood pressure of SHR was markedly reduced after 12weeks of aerobic exercise. RAS peptides in plasma were all increased with an imbalanced upregulation of Ang II and Ang-(1-7) in SHR, exercise revised the level of RAS and increased Ang-(1-7)/Ang II. The vasoconstriction response induced by Ang II was mainly via type 1 receptors (AT1R), while this contraction was inhibited by Mas receptor (MasR). mRNA and protein of AT1R and MasR were both upregulated in SHR, whereas exercise significantly suppressed this imbalanced increase and increased MasR/AT1R ratio. Exercise hypermethylated Agtr1a and Mas1 genes, associating with increased DNMT1 and DNMT3b and SAM/SAH. Aerobic exercise ameliorates vascular function via hypermethylation of the Agtr1a and Mas1 genes and restores the vasoconstrictor and vasodilator axes balance.

ASSOCIATION BETWEEN CARDIAC (PRO)RENIN RECEPTOR EXPRESSION AND MYOCARDIAL HYPERTROPHY IN HUMAN

Objective: The (pro)renin receptor [(P)RR] is expressed in vital organs throughout the body, with the highest expression level in the heart, and is thought to regulate the tissue renin-angiotensin system (RAS) through the non-proteolytic activation of prorenin. (P)RR is cleaved by processing enzymes to generate soluble (s)(P)RR, which is secreted into the extracellular space, and blood concentration of s(P)RR is considered to reflect the expression level of tissue RAS. Although it has been suggested that increased expression of (P)RR may be involved in cardiac pathophysiology in experimental studies, the significance of (P)RR expression in human heart remains unclear. Therefore, in the present studies, we investigated association between cardiac (P)RR expression and myocardial hypertrophy in human. Design and method: Study (1): We measured serum s(P)RR concentration and assessed the relationships between serum s(P)RR level and background factors including left ventricular mass index (LVMI) in 135 patients (57 males) of our department. Study (2): We performed immunostaining for (P)RR and atrial natriuretic peptide (ANP) and α-skeletal actin (SKA), markers for myocardial hypertrophy, in left ventricle specimens obtained from 13 autopsy cases. The expression level of (P)RR, ANP, or SKA and cardiomyocyte area were analyzed using an image processing software (ImageJ) and expression level of (P)RR was compared with cardiomyocyte area and expression level of ANP or SKA. Results: Study (1): The patients’ age was 57 (44–67) y.o., serum s(P)RR concentration was 22.8 (21.1–27.7) ng/ml, eGFR was 74.4 (59.4–91.2) ml/min/1.73 m2, and LVMI was 79 (66–90) g/ m2. Serum s(P)RR level was significantly positively correlated with LVMI (β = 0.238, p &lt; 0.01) independent of other related factors. Study (2): (P)RR immunostaining was observed in cytoplasm of cardiomyocytes. The expression level of (P)RR was significantly positively correlated with cardiomyocyte area (ρ = 0.386, p &lt; 0.001) and expression level of ANP (ρ = 0.782, p &lt; 0.001) or SKA (ρ = 0.373, p &lt; 0.001). Conclusions: These data suggested that cardiac (P)RR expression may be associated with myocardial hypertrophy in human. Further studies are needed to determine the underlying mechanism of this association.

The intracellular renin-angiotensin system: Friend or foe. Some light from the dopaminergic neurons.

The renin-angiotensin system (RAS) is one of the oldest hormone systems in vertebrate phylogeny. RAS was initially related to regulation of blood pressure and sodium and water homeostasis. However, local or paracrine RAS were later identified in many tissues, including brain, and play a major role in their physiology and pathophysiology. In addition, a major component, ACE2, is the entry receptor for SARS-CoV-2. Overactivation of tissue RAS leads several oxidative stress and inflammatory processes involved in aging-related degenerative changes. In addition, a third level of RAS, the intracellular or intracrine RAS (iRAS), with still unclear functions, has been observed. The possible interaction between the intracellular and extracellular RAS, and particularly the possible deleterious or beneficial effects of the iRAS activation are controversial. The dopaminergic system is particularly interesting to investigate the RAS as important functional interactions between dopamine and RAS have been observed in the brain and several peripheral tissues. Our recent observations in mitochondria and nucleus of dopaminergic neurons may clarify the role of the iRAS. This may be important for the developing of new therapeutic strategies, since the effects on both extracellular and intracellular RAS must be taken into account, and perhaps better understanding of COVID-19 cell mechanisms.

An evaluation of renin-angiotensin system markers in youth with type 2 diabetes and associations with renal outcomes.

Youth with type 2 diabetes (T2D) have high rates of obesity, hypertension and suboptimal glycemic control. We hypothesized that renin-angiotensin system (RAS) activation is present in youth with T2D and associated with poor glycemic control and renal outcomes. Cross-sectional analysis of 183 youth with T2D and 100 controls from the Improving renal Complications in Adolescents with T2D through REsearch cohort. Diabetes youth stratified by urine albumin:creatinine ratio (ACR) < or ≥2 mg/mmol. RAS levels measured with enzyme-linked immunosorbent assay (ELISA) and enzyme activities by synthetic substrates. In T2D, levels log transformed and Tobit linear regressions evaluated for associations with hemoglobin A1c (HbA1c), mean arterial pressure (MAP), estimated glomerular filtration rate (eGFR), ACR. Youth were 14 to 15 years, with diabetes duration 1.7 to 1.8 years; 21.3% albuminuria. Serum: differences in plasma renin activity (<0.0001), and angiotensin converting enzyme (ACE) activity (P = .003) in T2D vs controls. Urine: higher ACE activity and ACE2 protein/activity (all P < .0001) in T2D, higher levels in T2D with albuminuria. Multivariable regressions: higher serum ACE activity (ß = 0.03, SE 0.01;P < .01), urine ACE activity (ß = 0.44, SE 0.18;P < .01), ACE2 (ß = 0.51, SE 0.19;P < .01) positively associated with HbA1c; urine angiotensinogen (AGT) negatively associated (ß = -0.28 [SE 0.06;P < .01]). Higher serum aldosterone (ß = 0.11 [SE 0.04;P < .01]) and urine AGT (ß = 0.32 [SE 0.07;P < .01]) significantly associated with ACR and urine ACE2 (ß = 0.21 [SE 0.13;P < .03]). No associations between RAS markers and eGFR/MAP. RAS activation present in youth with T2D and associated with higher HbA1c. Higher serum aldosterone and urine AGT associated with albuminuria. The prognostic significance of the combined effect of glycemia and RAS activation on renal outcomes requires additional investigation.

The serum level of the components of the renin-angiotensin system correlates with its tumor tissue expression in kidney cancer patients.

e17068 Background: To date, it has not been decided whether the locally-generated components of the renin-angiotensin system (RAS) involved in the pathogenesis of kidney cancer and arterial hypertension, and are local and systemic RAS related? The aim was to assess the relationship of the level of RAS in the tumor tissue and peripheral blood in patients with localized kidney cancer with arterial hypertension. Methods: In patients with localized kidney cancer T1N0M0 (KС) and arterial hypertension of the I-II stage (AH), tissue and serum levels of angiotensin I, angiotensin II, angiotensin (1-7), as well as angiotensin converting enzymes (ACE and ACE2) were determined in the following groups: patients with KC without AH (n = 35, KC) and with concomitant AH (n = 30; KC+ AH). The normative values of peripheral blood indices were revealed in healthy donors (n = 30). Results: The level of all studied RAS peptides in the serum of patients with KC was increased in comparison with healthy donors regardless of concomitant hypertension, and the activity of both circulating angiotensin-converting enzymes, on the contrary, was increased only in patients with hypertension. The level of AT1 exceeds the control indicators by 1.7 times (KC) and 2.8 times (KC + AH). The formation of AT2 is higher in the KC + AH compared to KC (2.2 times versus 1.7 times, at p &lt; 0.05). The content of AT (1-7) significantly exceeds the control (1.3 times on average, p &lt; 0.05) and higher in the KC + AH. Increased enzyme activity was detected in KC + AG: increased by 1.5 times (p &lt; 0.05) and 1.7 (p &lt; 0.05) compared with the control for ACE and ACE2, respectively. The pair correlation coefficients between the serum RAS and the studied tissues in the KC were: for AT1 -0.78/0.65; АТ2-0.64/0.59 and АТ (1-7) - 0.56/0.51; ACE2 0.55/0.65 (for tumor/peritumoral tissue: in all cases at p &lt; 0.05). In the KC+AH, these ratios were: for AT1 -0.85/0.81; АТ2-0.72/0.74 and АТ (1-7) - 0.65/0.59; ACE2 0.61/0.52 (for tumor / peritumoral tissue: in all cases at p &lt; 0.05). Conclusions: The serum content of RAS peptides had positive statistical relationships with the corresponding parameters in tumor and peritumoral tissues of kidney cancer pts. However, in hypertensive patients with kidney cancer the correlations found had a tightness of higher strength. Positive correlations of the level of locally generated tumor parameters of RAS with their circulating analogues indicate the possibility of their use as diagnostic markers of the development of kidney cancer.

Losartan prevents the elevation of blood pressure in adipose-PRR deficient female mice while elevated circulating sPRR activates the renin-angiotensin system.

Deletion of the prorenin receptor (PRR) in adipose tissue elevates systolic blood pressure (SBP) and the circulating soluble form of PRR (sPRR) in male mice fed a high-fat (HF) diet. However, sex differences in the contribution of adipose-PRR and sPRR to the regulation of the renin-angiotensin system (RAS) in key organs for blood pressure control are undefined. Therefore, we assessed blood pressure and the systemic and intrarenal RAS status in adipose-PRR knockout (KO) female mice. Blockade of RAS with losartan blunted SBP elevation in HF diet-fed adipose-PRR KO mice. ANG II levels were significantly increased in the renal cortex of HF diet-fed adipose-PRR KO female mice, but not systemically. HF diet-fed adipose-PRR KO mice exhibited higher vasopressin levels, water retention, and lower urine output than wild-type (WT) mice. The results also showed that deletion of adipose-PRR increased circulating sPRR and total hepatic sPRR contents, suggesting the liver as a major source of elevated plasma sPRR in adipose-PRR KO mice. To mimic the elevation of circulating sPRR and define the direct contribution of systemic sPRR to the regulation of the RAS and vasopressin, C57BL/6 female mice fed a standard diet were infused with recombinant sPRR. sPRR infusion increased plasma renin levels, renal and hepatic angiotensinogen expression, and vasopressin. Together, these results demonstrate that the deletion of adipose-PRR induced an elevation of SBP likely mediated by an intrarenal ANG II-dependent mechanism and that sPRR participates in RAS regulation and body fluid homeostasis via its capacity to activate the RAS and increase vasopressin levels. NEW & NOTEWORTHY The elevation of systolic blood pressure appears to be primarily mediated by cortical ANG II in high-fat diet-fed adipose-prorenin receptor knockout female mice. In addition, our data support a role for soluble prorenin receptor in renin-angiotensin system activation and vasopressin regulation.

Water metabolism dysfunction via renin-angiotensin system activation caused by liver damage in mice treated with microcystin-RR

Microcystins (MCs) are a group of monocyclic heptapeptide toxins that have been shown to act as potent hepatotoxins. However, the observed symptoms of water metabolism disruption induced by microcystin-RR (MC-RR) or MCs have rarely been reported, and a relatively clear mechanism has not been identified. In the present study, male mice were divided into 4 groups (A: 140μg/kg, B: 70μg/kg,C: 35μg/kg, and D: 0μg/kg) and administered MC-RR daily for a month. On day 8 of treatment, an increase in water intake and urine output was observed in the high-dose group compared with the control, and the symptoms worsened with the repeated administration of the toxin until day 30. In addition, the urine specific gravity decreased and serum enzymes that can reflect hepatic damage increased in the high-dose group compared with the control (P<0.05). The mRNA level of angiotensinogen (AGT) in hepatocytes was upregulated to approximately 150% of the control (P<0.05), and the serum renin-angiotensin system (RAS) was activated in the high-dose group; however, signs of renal injury were not observed throughout the experiment. After the toxin treatment was completed, the high levels of the RAS and vasopressin in group A returned to normal levels within 1 week. As expected, the symptoms of polyuria and polydipsia also disappeared. Therefore, we propose that water metabolism dysfunction occurs via RAS activation caused by liver damage because the increased serum RAS levels in the experiment were consistent with the increased urine output and water intake in the mice during the observation period. In addition, we found for the first time that a RAS blocker could alleviate the observed polyuria and polydipsia and inactivate the high level of the RAS induced by MC-RR in a dose-dependent manner, which further supported our hypothesis.

The correlation between inflammatory injury induced by LPS and RAS in EpH4-Ev cells

Renin–angiotensin system (RAS) plays an important role of regulating inflammatory injury. However, it is not clear about the correlation between renin–angiotensin system (RAS) and inflammation induced by LPS in mammary gland cells. So immunofluorescence was performed to verify the ACE2 expression in mammary gland cells. MTT assay was performed to detect cell viability. ELISA was performed to detect cytokines in cell supernatant. Western Blot was performed to analyze RAS levels and ACE2 level change was observed by immunofluorescence. The TLR4 level and p65 phosphorylation were detected by Western Blot. The ACE2 protein intensively located on the cell membrane. According to the results of MTT assay and TNF-α level, the injury was evidently induced by high concentration LPS after 9h. The TNF-α, IL-6, IL-8, ACE, AT1R and AngII had an increasing expression with the rise of cell injury. In contrast, the MasR, Ang1-7 and ACE2 had a declining expression with the increase of cell injury degree. The TLR4 level and p65 phosphorylation in high concentration LPS group was significantly higher than that of control group. These results suggest that a valid inflammatory injury was induced after the cells were treated by high concentration of LPS for 9h. Meanwhile, the ACE/AngII/AT1R axis was activated and the ACE2/Ang1-7/MasR axis was depressed.

Natriuretic responses to angiotensin 1‐7 infusion in hypertensive rat models (1088.6)

Anti‐natriuretic properties of Angiotensin II in the kidney are counterbalanced by the opposing actions of Angiotensin 1‐7 (Ang 1‐7) in normal animals. This study investigated whether the response to Ang 1‐7 was altered in models of hypertension where the renin‐angiotensin system (RAS) was either suppressed (Deoxycorticosterone (DOCA) salt hypertensive) or enhanced (2‐Kidney‐1‐clip (2K1C) hypertensive). Hypertensive groups derived from male Wistar rats (n=4) were anaesthetised and prepared for renal interstitial infusion of Ang 1‐7 (3x10‐³ M) at 1ml/h into the left kidney and cannulation of its ureter. Data±SEM were subject to one‐way ANOVA. Ang 1‐7 had no effect on blood pressure, at 139mmHg for 2K1C rats and 154mmHg for DOCA Hypertensive rats. In 2K1C rats, sodium excretion (UVNa) increased from 6.1±1.4 to 8.7±2.2µmol/min and fractional sodium excretion (FENa) from 1.2±0.2 to 1.5±0.2%, similar to normal rats. Intra‐renal infusion of the same dose of Ang 1‐7 in the DOCA model has no effect on the excretory variables showing a statistically significant difference in the response of these two models. These data suggest that the action of Ang(1‐7) correlates with the level of RAS activation.Grant Funding Source: Supported by Science Foundation Ireland (SFI)

Pioglitazone upregulates hepatic angiotensin converting enzyme 2 expression in rats with steatohepatitis

Objective. Angiotensin II, one component of renin-angiotensin system (RAS), is formed from Ang I by the catalysing of angiotensin converting enzyme (ACE). Angiotensin II plays an important role in the development of insulin resistance. ACE2, a homologue of ACE, couterregulate the actions of angiotensin II by facilitating its breakdown to angiotensin-(1–7). RAS has been implicated in the pathogenesis of non-alcoholic steatohepatitis (NASH). Earlier demonstration that thiazolidinediones (TZDs) improve steatohepatitis promoted us to evaluate the change of hepatic ACE2 expression in rats with high fat diet (HFD)-induced NASH and the effects of TZDs on the hepatic ACE2 expression.Material and methods. Rats were divided into normal control group, high fat diet (HFD) group, and pioglitazone group. After 24 weeks of treatment with pioglitazone, a TZD, we evaluated changes in liver histology, insulin sensitivity, lipid metabolism, circulating RAS levels and hepatic ACE2 expression.Results. Compared with normal controls, the concentrations of serum lipid, aminotransaminase, glucose, insulin, ACE, angiotensin II, ACE2, angiotensin-(1–7) and the degree of hepatic ACE2 expression were significantly higher in rats with HFD-induced NASH. Pioglitazone significantly reduced the concentrations of serum lipid, aminotransaminase, glucose, insulin, ACE, angiotensin II while markedly raised the concentrations of serum ACE2, angiotensin-(1–7) and the degree of hepatic ACE2 expression.Conclusion. Hepatic ACE2 expression markedly increased in rats with HFD-induced NASH and was further upregulated by pioglitazone. Hepatic ACE2 may be a new target of pioglitazone treatment for NASH.

Renin–angiotensin system genetic polymorphisms: Lack of association with CRP levels in patients with coronary artery disease

Angiotensin (Ang) II is believed to be a potential pro-inflammatory factor. The capability of Ang II to stimulate C-reactive protein (CRP) production has recently been described. Genetic polymorphisms of renin angiotensin system (RAS) components have been described to be associated with the development of coronary artery disease (CAD). This study investigated the association between six different genetic polymorphisms of RAS and serum CRP levels in a sample of CAD patients. Genotyping of RAS genes polymorphisms in 176 patients with documented CAD was performed by a modified polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Measurement of high-sensitivity (hs)-CRP was performed using standard immunoturbidimetric methods. Results show no significant differences in serum CRP regarding different variants of the six polymorphisms studied (p = 0.41, 0.24, 0.25, 0.19, 0.29, and 0.05 for Ang-converting enzyme (ACE) insertion/deletion (I/D), A-240T and A2350G, angiotensinogen M235T, AT1 receptor A1166C, and AT2 receptor C3123A polymorphisms, respectively). In conclusion, genetic polymorphisms of RAS are not associated with increased serum CRP in CAD. Compensation of an increased activity of ACE through counter-regulation and the secretion of CRP under the influence of Ang II in the vessel being local could explain the lack of association between the studied polymorphisms and CRP levels in CAD patients.

Prenatal exposure to interleukin‐6 results in hypertension and alterations in the renin–angiotensin system of the rat

Cytokines are emerging as important in developmental processes. They may induce alterations in normal gene expression patterns, activate angiotensinogen transcription, or alter expression of the renin-angiotensin system (RAS). To determine whether prenatal exposure to interleukin-6 (IL-6) influences gene expression of the intrarenal RAS and contributes to renal dysfunction and hypertension in adulthood, we exposed female rats to IL-6 early (EIL-6 females) and late (LIL-6 females) in pregnancy and analysed blood pressure in the offspring at 5-20 weeks of age. Renal fluid and electrolyte excretion was assessed in clearance experiments, mRNA expression by real-time PCR, and protein levels by Western blot. Systolic pressure was increased at 5 weeks in IL-6 females and at 11 weeks in males. Circulatory RAS levels were increased in all IL-6 females, but angiotensin-1-converting enzyme (ACE) activity was increased only in LIL-6 females. LIL-6 males and IL-6 females showed decreased urinary flow rate and urinary sodium and potassium excretion. Dopamine excretion was decreased IL-6 females. In adult renal cortex, renin expression was increased in all IL-6 females, but angiotensinogen mRNA was increased only in LIL-6 females; AT(1) receptor (AT(1)-R) mRNA and protein levels were increased in LIL-6 females, whereas AT(2) receptor (AT(2)-R) levels were decreased in LIL-6 females and EIL-6 males. In adult renal medulla, AT(1)-R protein levels were increased in LIL-6 females, and AT(2)-R mRNA and protein levels were decreased in EIL-6 males and LIL-6 females. Prenatal IL-6 exposure may cause hypertension by altering the renal and circulatory RAS and renal fluid and electrolyte excretion, especially in females.

292 EFFECTS OF ACUTE SALT LOADING ON BLOOD PRESSURE REGULATION IN THE NEWBORN LAMB

The normal newborn has an impaired conservation of sodium; high renin-angiotensin system (RAS) levels; and a decreased pressor responsiveness to angiotensin 11(A-11). The purpose of this study was to determine whether increasing the newborn salt intake would suppress the high RAS levels and alter blood pressure(BP) responsiveness. In Exper 1, 8 newborn lambs were infused with NaCl 10 mEq/kg in 20 ml/kg 5%D/W over 60 min, followed by serial doses of A-11 (0.025, 0.5, 0.1, and 0.25 ug/kg/min), each for 15 min. Mean aortic BP was monitored continuously. In Exper 2 (0.25 ug/kg/min) was infused into 5 newborn lambs after a similar NaCl loading. Plasma renin activity (PRA) was measured before and at 5, 15, and 30 min of the A-11 infusion. In Exper 1, A-11 (0.025 ug/kg/min) increased BP 30 mm Hg in the ewe, caused no change in the control newborn, and increased BP 15 mm Hg in the volume expanded newborn; (0.25 ug/kg/min) increased BP 30 mm Hg in the control newborn and 40 mm Hg in the volume expanded newborn. In Exper 2, PRA decreased from 22.1 ± 2.1 ng/ml/hr (M and SEM) to 10.8 ± 2.1 (p<.05) after the volume expansion alone, and to 5.2 ± 1.0 (p<.05) after 30 min of the A-11 infusion. BP decreased 10 mm Hg after the salt loading alone. In conclusion: Acute salt loading, 1) increases the pressor responsiveness to A-11; 2) suppresses the renin-angiotensin system; and 3) decreases basal BP in the newborn lamb. Therefore, the reninangiotensin system control of BP and A-11 responsiveness may be related to the newborn sodium state.