Renal Venous Blood Research Articles

Abstract P206: Renal hemodynamic and transcriptomic changes in response to salt in Dahl salt-sensitive rats

Introduction: Continuous measurements (24/7) of arterial pressure (AP) and renal blood flow (RBF), along with intermittent sampling of arterial and renal venous blood and urine in freely moving rats, have enabled the determination of sequential changes in global substrate metabolism and their association with physiological responses in the kidney. It was found that salt loading in Sprague-Dawley (SD) rats resulted in an increase in RBF and renal O 2 consumption with minimal changes in AP. At the same time, TCA cycle pathway was downregulated with reduced metabolism of free fatty acids and amino acids, while glycolysis was upregulated, in the kidney cortex (Cx). In contrast, no significant changes were observed in metabolism-related pathways in the outer medulla (OM). (PMID: 37575482). Here, we report transcriptomic responses of Dahl salt-sensitive (SS) rats to the HS diet as compared to the salt-resistant SD rats. Method: Male SS rats were fed a 0.4% NaCl (LS) diet. At 8 weeks of age, the rats were implanted with an RBF probe together with an arterial and a renal venous catheter. RBF and AP were measured continuously, and arterial and renal venous blood and urine were sampled when rats were fed the LS and on days 7, 14, and 21 after switching to the 4.0% NaCl (HS) diet. From separate groups of rats subjected to the same protocol, Cx and OM were removed for mRNAseq analysis (Novogene, Inc). Results: When switching to the HS diet, mean AP of SS rats rose from 122 ± 2 to 164 ± 5 mmHg by HS21. RBF (mL/min/g kidney weight) fell significantly over the 3 weeks of the HS diet averaging 7.2 ± 0.6 (LS) to 4.6 ± 0.7 (HS21). The gene set enrichment analysis (GSEA) of the mRNAseq data revealed that only a few metabolic pathways were enriched in HS7 in Cx such as glycosphingolipid biosynthesis, while metabolic pathways such as linolenic acid and arachidonic acid metabolism and glycosphingolipid biosynthesis were enriched in OM. Downregulation of the lysine degradation and glutathione metabolic pathways was observed in both Cx and OM in HS21. In general, fewer metabolic pathways responded to HS in SS rats compared to SD in Cx (22 in SD vs 7 in SS). Conclusion: The Cx of SS rats appear less capable of adjusting to the increased metabolic needs imposed by a HS diet compared to SD rats in contrast to the OM. The functional implications of this are being examined and the metabolomic analysis of blood, tissue and urine samples is currently in progress at the JAX lab.

Local and Systemic Micro-Rheological Changes during Intestinal Anastomosis Operation: A Metabolic Dependence in an Experimental Model.

Hemorheological factors may show arterio-venous differences. Alterations in acid-base and metabolic parameters may also influence these factors. However, little is known about changes in micro-rheological parameters during abdominal surgery, influencing splanchnic circulation. In anesthetized pigs, the external jugular vein, femoral artery and vein were cannulated unilaterally, and paramedian laparotomy was performed. In the anastomosis group, after resecting a bowel segment, end-to-end jejuno-jejunostomy was completed. Blood samples (from cannulas and by puncturing the portal vein) were taken before and after the intervention. Hematological, acid-base and blood gas parameters, metabolites, red blood cell (RBC) deformability and aggregation were determined. The highest hematocrit was found in portal blood, increasing further by the end of operation. A significant pH decrease was seen, and portal blood showed the highest lactate and creatinine concentration. The highest RBC aggregation values were found in arterial, the lowest in renal venous blood. The RBC aggregation increased with higher lactate concentration and lower pH. Osmotic gradient deformability declined, with the lowest values in portal and renal venous samples. In conclusion, micro-rheological parameters showed arterio-venous and porto-renal venous differences, influenced by oxygenation level, pH and lactate concentration. The intestinal anastomosis operation caused an immediate micro-rheological deterioration with portal venous dominancy in this experiment.

Multi-omics analysis of renal vein serum with Ischemia-Reperfusion injury

BackgroundAcute kidney injury (AKI) is frequently caused by renal ischemia–reperfusion injury (IRI). Identifying potential renal IRI disease biomarkers would be useful for evaluating AKI severity. ObjectiveWe used proteomics and metabolomics to investigate the differences in renal venous blood between ischemic and healthy kidneys in an animal model by identifying differentially expressed proteins (DEPs) and differentially expressed protein metabolites (DEMs). MethodsNine pairs of renal venous blood samples were collected before and at 20, 40, and 60 min post ischemia. The ischemia time of Group A, B and C was 20,40 and 60 min. The proteome and metabolome of renal venous blood were evaluated to establish the differences between renal venous blood before and after ischemia. ResultsWe identified 79 common DEPs in all samples of Group A, 80 in Group B, and 131 in Group C. Further common DEPs among all three groups were Tyrosineprotein kinase, GPR15LG, KAZALD1, ADH1B. We also identified 81, 64, and 83 common DEMs in each group respectively, in which 30 DEMs were further common to all groups. Bioinformatic analysis of the DEPs and DEMs was conducted. ConclusionThis study demonstrated that different pathological processes occur during short- and long-term renal IRI. Tyrosine protein kinase, GPR15LG, Kazal-type serine peptidase inhibitor domain 1, and all-trans-retinol dehydrogenase are potential biomarkers of renal IRI.

#2848 Persistent albuminuria is a marker of persistent congestion in patients with chronic heart failure

Abstract Background and Aims Albuminuria is prevalent in patients with heart failure (HF) and associated with poor prognosis. Initial reports indicate albuminuria as a congestion marker in HF. Frequency and associations of persistent albuminuria with kidney function, NT-proBNP and venous congestion in this population are not clearly understood. We aimed to evaluate the dynamics of albuminuria and its relationship with congestion and renal function in patients with chronic HF (CHF). Method The study included patients ≥18 years, observed in an outpatient HF center, who signed an informed consent. Patients receiving renal replacement therapy, with cancer or primary kidney diseases were excluded. The visits were carried out with an interval of 3 months. During each visit we performed routine physical examination, laboratory tests (NT-proBNP, urine albumin/creatinine ration (uACR), and serum creatinine) and pulse-wave Dopplerography to assess renal venous blood flow. Persistent albuminuria was defined as maintaining an uACR > 30 mg/g on two visits. Albuminuria level was assessed according to KDIGO guidelines 2012 (A1, A2, A3). The absence of venous congestion was defined as continuous renal blood flow, while venous congestion - as intermittent (biphasic or monophasic) blood flow. A P value <0.05 was considered statistically significant. We prospectively included 103 patients with CHF (46% male, mean age - 70 (61;75) Me (IQR) years, 53% with reduced ejection fraction (EF), mean EF 45(34;53)%, 92% hypertensive, 60% with atrial fibrillation, 34% with diabetes mellitus type 2, 51% with chronic kidney disease (CKD), 43% with coronary heart disease). Results Mean uACR values at the 1st visit was 18(8;56) mg/g, at the 2nd visit - 11(0;35) mg/g. The frequency of albuminuria levels at the 1st visit were A1-66%, A2-26%, A3-8%; at the 2nd visit – A1-73%, A2-23%, A3-4%. Persistent albuminuria was detected in 37 patients (36%). The mean values of albuminuria were higher in the persistent albuminuria group on the 1st visit (76(39;222) vs 10.5(0;19.5) for patients with and without persistent albuminuria, p<0.001) and on the 2nd visit (94(44;176) vs 7(0;13), p < 0.001). The patient groups were comparable in gender, age, frequency of comorbidities, EF. The administration of disease-modifying therapy was the same in the groups, however, the dose of loop diuretic was higher in the group of persistent albuminuria (20 (10;75) vs 10(5;20) mg respectively, p = 0.024 (doses in terms of furosemide)). Serum creatinine level was 95(79;121) mmol/l; GFR (CKD-EPI 2021)- 69(52;88) mL/min/ 1.73 m2 at the 1st visit. Kidney function did not statistically differ in the groups with and without persistent albuminuria (at the 1st visit eGFE - 63(52;87) vs 70 (50;90) mL/min/1.73 m2, p = 0.52 and the 2nd visit eGFR- 68(48;85) vs 66 (48;89) mL/min/1.73, p = 0.65 respectively). The level of NT-proBNP was higher in patients with persistent albuminuria during the 1st (926 (472;1820) vs 550(260;919), pg/ml p = 0.04) and the 2nd visit (1244(987;2000) vs 593(264;1405), pg/ml, p = 0.0008). Intermittent renal veins blood flow on the 2nd visit was observed in 26 patients (25%). In patients with persistent albuminuria persistence of intermittent venous renal blood flow was more frequently than in patients without it (43% vs 7%, p = 0.017, respectively). Figs. 1 and 2 demonstrate that renal venous congestion was more severe in group of persistent albuminuria on visit 1st and 2nd respectively. Conclusion Persistent albuminuria over 3 mounts in patients with stable chronic heart failure is associated with persisting congestion (higher NT-proBNP levels and higher incidence and severity of renal venous congestion). There was no association between changes in albuminuria and changes in renal function.

#2999 Renal venous congestion as a predictor of poor prognosis in patients with acute decompensated heart failure

Abstract Background and Aims Systemic venous congestion in acute decompensated heart failure (ADHF) is associated with a risk of end-organ damage and high in-hospital mortality. We aimed to assess the prevalence and severity of renal venous congestion using venous excess ultrasound (VExUS) protocol in intensive care unit (ICU) patients with ADHF, and to evaluate the association between type of intra-renal venous blood flow, incidence of acute kidney injury (AKI), and in-hospital death. Method A prospective single-center study included 99 patients who were admitted to the ICU with ADHF (mean age 71.1 ± 12.54 years, 56 (56.6%) males). Inclusion criteria: age ≥18 years, ADHF II–IV, signed informed consent. Exclusion criteria: acute coronary syndrome, severe concomitant diseases, refusal to participate in the study. Upon admission, routine clinical, laboratory and instrumental examinations, lung ultrasound using the BLUE protocol, and assessment of venous congestion using the pulse-wave dopplerography were performed. The presence of continuous blood flow was regarded as the absence of renal venous congestion, while intermittent (biphasic and monophasic blood flow) indicated venous congestion. The diagnosis of ADHF and AKI was established based on generally accepted criteria in accordance with modern international recommendations. All patients received optimal drug therapy. The end point was defined as death from cardiovascular causes during hospitalization. Statistical analysis was performed using SPSS Statistics, version 26.0. Results Upon admission, continuous renal venous blood flow was detected in 17 (17.2%) patients, intermittent in 82 (82.8%): biphasic in 47 (47.5%) and monophasic in 35 (35.3%). The patient groups were comparable in gender, age, frequency of coronary heart disease, diabetes mellitus, anemia. Atrial fibrillation was more common in case of monophasic (p < 0.006), and arterial hypertension in patients with continuous venous blood flow (p < 0.001). Patients with renal venous congestion, compared with patients without signs of congestion, had more severe heart failure: swollen neck veins: 5 (29.4%) vs 21 (45%) vs 28 (60%), p < 0.001; hepatomegaly 12 (72.6%) vs 40 (85.1%) vs 31 (88.6%), p < 0.001; edema 8 (47.3%) vs 40 (85.1%) vs 24 (68.6%), p < 0.001; NYHA functional class IV 8 (47.1%) vs 32 (68.1%) vs 26 (74.6%), p < 0.001; more B-lines on lung ultrasound, M+SD 28.82 ± 8.91 vs 34.38 ± 9.64 vs 35.37 ± 8.72, p < 0.001, higher NTproBNP levels, pg/l, Ме(IQR) 2100 (1800;4560) vs 3418 (2300;8434) vs 4100 (2500;9282), p < 0.001, and albuminuria levels mg/g, Ме(IQR) 85 (29;145) vs 127 (49;248) vs 139 (64;245), p < 0.001. The incidence of AKI (4 (23.5%) vs 23 (49%) vs 31 (88.6%), p < 0.001), and in-hospital death (0 (0) vs 11 (23.4%) vs 12 (34.3%), p < 0.003) was also higher in the group of patients with monophasic renal blood flow. The presence of renal venous congestion on admission was associated with an increased risk of death due to heart failure during hospitalization with RR 1.32 (95% CI: 1.16-2.64), p < 0.001, and RR 1.64 (95% CI: 1.48-2.83), p < 0.001 in patients with biphasic and monophasic renal venous blood flow respectively, and with development of AKI RR 3.29 (95% CI: 1.50-7.24), p < 0.003 in patients with monophasic renal venous blood flow. Conclusion In ICU patients with ADHF, the presence of renal venous congestion, assessed on admission with Doppler ultrasound of the intrarenal veins using the VEXUS protocol, is associated with a high risk of developing AKI and in-hospital death.

NADPH Oxidase 4 Knockout in Dahl Salt-Sensitive Rats Impacts Kidney O2 Consumption and UCP2 Responses to a High Salt Diet

Rationale: The effects of a high salt (HS) diet upon renal metabolism and O2 utilization have not been extensively studied and there is a significant gap in our understanding of the role of oxidative stress in the effciency of energy production and substrate metabolism. The present study compared the effects of a HS diet (4% NaCl) on changes in O2 consumption and transcriptomic profiles in Dahl salt-sensitive (SS) rats to SS rats with a global knockout of NADPH oxidase 4 (NOX4) gene (SS Nox4−/−). Methods: Male SS (n=9) and SS Nox4−/− (n=10) rats were fed a 0.4% NaCl (LS) diet. At 7-8 weeks of age, the rats were implanted with a renal artery ultrasonic flow probe (Transonic) together with a femoral arterial catheter and a renal venous catheter. Renal blood flow (RBF) and mean arterial pressure (MAP) were measured continuously (24/7) and arterial (A) and renal venous (Vr) blood was sampled intermittently when rats were fed the LS and on days 7, 14, and 21 after switching to the HS diet. A and Vr blood O2 content was immediately measured by radiometer. From separate groups of rats subjected to the same protocol, the renal cortical tissue (Cx) and outer medulla (OM) were removed for mRNAseq analysis (Novogene, Inc). Results: When switching to the HS diet, the average 24-hour MAP of SS rats rose from 122 ± 2 to 140 ± 2 on HS7 to 164 ± 5 mmHg by HS21. In contrast, MAP in SS Nox4−/− rats increased from 121 ± 2 at LS to 132 ± 1 at HS7 to 152 ± 3 mmHg at HS21 (p<0.05, compared to SS). RBF, normalized by changes of kidney weights obtained in another group of SS and SS Nox4−/− rats fed the same HS diet, SS rats exhibited a significant reduction of RBF over the 3 weeks of the HS diet averaging LS 7.2 ± 0.6, HS7 5.1 ± 0.5 and HS21 4.6 ± 0.7 mL/min/g kidney weight (gkw). This reduction of RBF was not observed in SS Nox4−/− rats (LS 6.8 ± 0.8, HS7 6.6 ± 0.6, HS21 6.0 ± 0.6 mL/min/gkw). The kidney O2 extraction ratio at LS tended to be lower in SS Nox4−/− (11.2 ± 1.7%) compared to SS (14.0 ± 1.1%) (p=0.10). When switched to the HS diet, O2 extraction was significantly reduced in the SS Nox4−/− rats reaching 8.3 ± 1.0% at HS21 (p<0.05), while it did not change significantly in SS (12.7 ± 1.4%) at HS21. Notably, as determined by RNAseq analysis, Ucp2 expression in cortical tissue was significantly greater in SS fed HS than in SS Nox4−/−rats at HS21 . A gene enrichment analysis of the mRNAseq cortical tissue data (GSEA-KEGG pathways) focused on metabolic pathways indicated that knockout of Nox4 resulted in reduced expression of linoleic acid, lysine, and histidine metabolism pathways at LS when compared to SS. Those differences were not observed after HS feeding. However, upregulation of oxidative phosphorylation pathway was observed at HS21 in SS Nox4−/− when compared to SS rats. In the OM, a greater expression of genes associated with fatty acid degradation and carbon metabolism was observed in SS Nox4−/− rats when fed LS which was observed also at HS21. Conclusion: The preliminary results of this study suggest that reduced extraction of O2 in the SS Nox4−/− rats compared to SS rats may be partially explained by the differential response of Ucp2 to salt. Further studies are needed to determine whether the effciency of ATP production is enhanced in SS Nox4−/− as consequence of reduction of reactive oxygen species (e.g., H2O2) and the related downstream pathways such as phosphorylation of mTORC1. R01 HL151587, AHA 23POST1008714. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A study of size-selective renal elimination using a novel human model

The recently discovered selective glomerular hypofiltration syndromes have increased interest in the actual elimination of molecules in the human kidney. In the present study, a novel human model was introduced to directly measure the single-pass renal elimination of molecules of increasing size. Plasma concentrations of urea, creatinine, C-peptide, insulin, pro-BNP, β2-microglobulin, cystatin C, troponin-T, orosomucoid, albumin, and IgG were analysed in arterial and renal venous blood from 45 patients undergoing Transcatheter Aortic Valve Implantation (TAVI). The renal elimination ratio (RER) was calculated as the arteriovenous concentration difference divided by the arterial concentration. Estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI equations for both creatinine and cystatin C. Creatinine (0.11 kDa) showed the highest RER (21.0 ± 6.3%). With increasing molecular size, the RER gradually decreased, where the RER of cystatin C (13 kDa) was 14.4 ± 5.3% and troponin-T (36 kDa) was 11.3 ± 4.6%. The renal elimination threshold was found between 36 and 44 kDa as the RER of orosomucoid (44 kDa) was −0.2 ± 4.7%. The RER of creatinine and cystatin C showed a significant and moderate positive linear relationship with eGFR (r = 0.48 and 0.40). In conclusion, a novel human model was employed to demonstrate a decline in renal elimination with increasing molecular size. Moreover, RERs of creatinine and cystatin C were found to correlate with eGFR, suggesting the potential of this model to study selective glomerular hypofiltration syndromes.

Features of changes in the heart, blood vessels and internal organs in men with hypertension, depending on the value of the body mass index

Objective: study of the features of changes in the heart, blood vessels and internal organs (liver and kidneys) in men with hypertension, depending on the BMI value. Materials and methods: 194 men aged 25 to 63 with hypertension were examined. All the examined patients were divided into 3 groups depending on the BMI value. All patients included in the study were determined by serum creatinine (calculated by GFR), glucose, aspartate aminotransferase, alanine aminotransferase, lipid spectrum, uric acid. In addition, echocardiography, ultrasound of the kidneys with measurement of arterial and venous blood flow through the main vessels of the kidneys, ultrasound of the liver were performed. In the future, the groups were compared with each other according to the studied laboratory and instrumental data. Results: as the BMI values increased, the indicators of alanylaminotransferase, IFDS, RWT LV, MMLV, IMLV, the size of the right lobe of the liver, the incidence of hepatosteatosis significantly increased. Adherence to antihypertensive therapy in the selected groups ranged from 18,9 to 20,5%. Bilateral disorders of outflow through the renal veins were 1,8 times more common among people with normal BMI compared with obesity (p<0.05). Conclusion: among the examined young men with hypertension, there are features of an unfavorable "cardiological" profile and low adherence to antihypertensive therapy, which, as the age and length of the disease increases, is associated with a high risk of developing associated clinical conditions in the future. In male patients with hypertension and obesity, the incidence of hepatosteatosis is 100%, having an additional adverse effect on cardiovascular risk. The revealed features of renal venous blood flow among patients with hypertension deserve further investigation.

Abstract 040: Evidence Of Increased Glycolysis In Renal Cortex Of High Salt Fed Sprague Dawley Rats

To determine whole kidney O 2 and substance metabolism in an unanesthetized state, arterial (A), renal venous (Vr) blood and urine (U) were analyzed together with measurements of renal blood flow (RBF), blood pressure (BP) and GFR in conscious freely moving male SD rats. RBF and BP were measured continuously (24/7) via chronically implanted ultrasonic flow probe and A-line respectively. A and Vr blood through chronically implanted catheters and urine (U) were sampled intermittently when rats were fed a 0.4% NaCl (LS) diet and on days 7, 14, and 21 after switching to a 4.0% NaCl (HS) diet (HS7, HS14, HS21). A and Vr O 2 contents were determined by radiometer and a global metabolomic analysis was performed at the JAX Laboratory (LC-MS-MS). GFR was determined in another group of rats by transcutaneous detection of the attenuation of i.v. injected FITC sinistrin. Cortical (Cx) and outer medullary (OM) tissues were obtained from the other group of rats and underwent metabolomic and mRNAseq analyses (Novogene). From another group of rats, glomeruli (Glo), proximal tubules (PT) and non-PT were isolated for RT-PCR. BP and RBF slightly increased by HS3 (P<0.05) and were sustained at these levels. O 2 extraction rose progressively from 0.10 ± 0.01 at LS to 0.14 ± 0.01 at HS21 (P<0.05). GFR increased from 0.64 to 0.83 mL/min/100 g (P<0.05) at HS7 and sustained. Na + reabsorption and O 2 consumption were positively correlated. Clear distinctions were observed in a sparse partial least squares discriminant analysis of tissue metabolomics among LS, HS14, and HS21. The mRNAseq analysis found that the HS diet resulted in the activation of immune system-related genes in both Cx and OM and the downregulation of genes related to the TCA cycle and metabolism of amino acids and fatty acids in Cx only. In contrast, glycolysis-related genes including hexokinase ( Hk ) and pyruvate kinase ( Pkm ) were upregulated in Cx. Metabolic fluxes (A-Vr-U) showed the increased release of lactate and pyruvate from the kidney when fed HS. Increased mRNA expression of Hk and Pkm in HS21 was observed only in PT but not in Glo and non-PT. In summary, SD rats fed a HS diet underwent changes in RBF, O 2 extraction, and utilization of substrates with evidence of increased glycolysis.

Abstract P214: Impact Of NADPH Oxidase 4 Knockout On Renal O 2 Consumption In Dahl Salt-sensitive Rats

It has been generally thought that in normal Sprague-Dawley (SD) rats, a high salt diet has minimal impact on blood pressure and kidney function. However, as we have recently reported, the kidneys of SD rats fed a 4.0% NaCl diet (HS) exhibit enhanced O 2 consumption (VO 2 ) and marked changes in the metabolic pathways responsible for the generation of ATP and reactive oxygen species (ROS). In the current study, we examined the level of renal VO 2 in Dahl salt-sensitive (SS) rats and those in which the NADPH Oxidase 4 (NOX4) gene was globally knocked out (SS Nox4 -/- ). Male SS (n=9) and SS Nox4 -/- (n=10) rats were fed a 0.4% NaCl (LS) diet. At 7-8 weeks of age, the rats were implanted with a renal artery ultrasonic flow probe (Transonic) together with a femoral arterial catheter and a renal venous catheter. Renal blood flow (RBF) and mean arterial pressure (MAP) were measured continuously (24/7) and arterial (A) and renal venous (Vr) blood was sampled intermittently when rats were fed a LS and on days 7, 14, and 21 after switching to a HS diet. Blood O 2 content was immediately measured by a radiometer. The average 24-hour MAP of SS rats rose after switching to a HS diet from 122 ± 2 on the LS to 140 ± 2 on HS7, and to 164 ± 5 by HS21. In contrast, MAP in SS Nox4 -/- rats increased from 121 ± 2 mmHg at LS to 132 ± 1 mmHg at HS7 and 152 ± 3 mmHg at HS21 (p<0.05). RBF was not significantly changed but tended to progressively rise in both strains of rats with 24-hr flows averaging 7.8 ± 0.7 ml/min when fed LS and 8.9 ± 1.0 ml/min at HS21, and SS Nox4 -/- from 6.9 ± 0.7 to 8.2 ± 0.9. Normalized by changes of kidney weights obtained in another group of SS and SS Nox4 -/- rats, RBF was significantly reduced over the 3 weeks of the HS diet given the increase of kidney weights (SS LS 7.0 ± 0.6, HS7 5.7 ± 0.5, HS21 4.9 ± 0.6; SS Nox4 -/- LS 6.4 ± 0.7, HS7 6.2 ± 0.7, HS21 5.4 ± 0.7). Most importantly, the O 2 extraction ratio at LS was lower in SS Nox4 -/- (10.5 ± 1.0%) compared to SS (14.6 ± 1.0%) (p<0.05). When switched to the HS diet, this was further reduced in the SS Nox4 -/- rats reaching 7.6 ± 0.9% at HS21 (p<0.05), while it did not change significantly in SS (13.3 ± 1.4%) at HS21. We conclude that the elevated levels of renal O 2 consumption observed in SS rats are at least in part a consequence of increased oxidative stress associated with NOX4.

Renal venous Doppler ultrasound – a new parameter for predicting outcomes in patients with decompensated heart failure

Aim. To assess the frequency, dynamics, and prognostic value of renal venous congestion using Doppler ultrasound in patients with decompensated heart failure (DHF).Materials and methods. A prospective, single-center study included 124 patients with DHF (mean age 70 ± 12 years, 51.6% were males), left ventricular ejection fraction (LVEF) 44 [34; 55] %, N-terminal pro B-type natriuretic peptide (NT-proBNP) 1,609 [591; 2,700] pg / ml. All patients underwent a standard physical examination and laboratory and instrumental tests, including the assessment of the NT-proBNP level. Renal venous blood flow was assessed using pulsed-wave Doppler ultrasound. The presence of continuous renal blood flow was considered as the absence of venous congestion, while intermittent blood flow (two-phase and single-phase flow) indicated venous congestion. Rehospitalization for DHF and reaching a composite endpoint (rehospitalization for DHF and cardiovascular mortality) within 12 months after discharge were selected as endpoints.Results. At admission, continuous renal venous blood flow was observed in 34 (27.4%) patients, intermittent renal venous blood flow was found in 90 (72.6%) patients: two-phase flow in 62 (50%) and single-phase flow in 28 (22.6%) patients with DHF. At discharge, 66 (53.2%) patients had intermittent renal venous blood flow: two-phase flow in 50 (40.3%) and single-phase flow in 16 (12.9%) patients. Correlations of renal venous congestion with the levels of NT-proBNP, serum iron, uric acid, creatinine, LVEF, systolic pressure in the pulmonary artery (SPPA), and the development of acute kidney injury (AKI) were revealed. Persistent renal venous congestion at discharge was significantly associated with a higher probability of rehospitalization for DHF (hazard ratio (HR) 1.93 95% confidence interval (CI) (1.017–3.67); p = 0.044) and a composite endpoint (HR 2.66, 95% CI (1.43–4.96); p = 0.002).Conclusion. In patients with DHF, it is necessary to evaluate renal venous blood flow using pulsed-wave Doppler ultrasound to stratify patients with development of cardiovascular complications within 12 months.

Metabolic Responses of Normal Rat Kidneys to a High Salt Intake.

In this study, novel methods were developed, which allowed continuous (24/7) measurement of arterial blood pressure and renal blood flow in freely moving rats and the intermittent collection of arterial and renal venous blood to estimate kidney metabolic fluxes of O2 and metabolites. Specifically, the study determined the effects of a high salt (HS; 4.0% NaCl) diet upon whole kidney O2 consumption and arterial and renal venous plasma metabolomic profiles of normal Sprague-Dawley rats. A separate group of rats was studied to determine changes in the cortex and outer medulla tissue metabolomic and mRNAseq profiles before and following the switch from a 0.4% to 4.0% NaCl diet. In addition, targeted mRNA expression analysis of cortical segments was performed. Significant changes in the metabolomic and transcriptomic profiles occurred with feeding of the HS diet. A progressive increase of kidney O2 consumption was found despite a reduction in expression of most of the mRNA encoding enzymes of TCA cycle. A novel finding was the increased expression of glycolysis-related genes in Cx and isolated proximal tubular segments in response to an HS diet, consistent with increased release of pyruvate and lactate from the kidney to the renal venous blood. Data suggests that aerobic glycolysis (eg, Warburg effect) may contribute to energy production under these circumstances. The study provides evidence that kidney metabolism responds to an HS diet enabling enhanced energy production while protecting from oxidative stress and injury. Metabolomic and transcriptomic analysis of kidneys of Sprague-Dawley rats fed a high salt diet.

The effects of excess salt intake on the kidney metabolism in normal Sprague Dawley rats.

Introduction: This study aimed to determine the effects of a high salt diet upon the metabolism of O 2 and substances in the kidney in normal Sprague Dawley (SD) rats. Methods were developed enabling the intermittent collection of renal arteriovenous (A-Vr) blood and urine samples and to measure renal blood flow (RBF) and arterial pressure (BP) in conscious freely moving rats with GFR determined in a separate group of conscious rats. Other groups were studied to obtain cortical (Cx) and outer medullary (OM) tissue samples for associated transcriptomic and metabolomic profiles. Methods: SD rats were instrumented with a renal arterial ultrasonic flow probe, a femoral arterial and renal venous catheters, and RBF and BP measured continuously (24/7). Arterial (A) and renal venous (Vr) blood and urine were collected repeatedly before and 7, 14, and 21 days after increasing the salt diet from 0.4% (LS) to 4% (HS) NaCl. GFR was measured in age-matched rats and used as control shams for normalization. Blood O 2 content was determined by radiometry. A global metabolomic analysis was performed on plasma and Cx and OM tissue samples at JAX laboratories (Thermo Q-Exactive Orbitrap coupled to Vanquich UPLC system) and together with mRNAseq analysis for Cx and OM by Novogene Inc. Results: BP increased less than 5 mmHg by day 3 of the HS diet while RBF rose nearly 20% (P<0.05) and both were sustained at this level throughout the study. O 2 delivery, O 2 consumption (VO 2 ) and O 2 extraction rose over the 21 days of the HS diet (P<0.05). Total GFR increased from 0.64 to 0.83 mL/min/100 g bw (P<0.05) at HS 7 and remained elevated at HS 21. Whole kidney Na + reabsorption and kidney VO 2 were highly correlated positively (r=0.99). A sparse partial least squares discriminant analysis (sPLS-DA) of metabolomics for each of the 4 modes (C18 +/- and HILIC +/-) revealed clear distinctions between LS, HS14, and HS21 within Cx and OM. The mRNAseq tissue analysis found that the HS diet resulted in reduced expression of genes related to the TCA cycle and metabolism of amino acids and fatty acids. This was consistent with the metabolomic data showing a reduction of tissue citrate and succinate levels. In contrast, glycolysis-related genes including hexokinase, pyruvate kinase and lactate dehydrogenase were upregulated in the Cx tissue by HS. Minimal changes in metabolic pathways were observed in the OM tissue. A-Vr x RBF enabled metabolomic flux determination which showed the release of glucose on LS fed rats which was not evident with the HS diet. Uptake of citrate which was seen on LS was less evident on HS but there was a clear tendency observed for increased release of lactate, pyruvate, and α-ketoglutarate. Conclusions: Normal SD rats fed a HS underwent changes of RBF, O 2 extraction and utilization of metabolic substrates, most notably transitioning ATP production predominantly driven from TCA cycle to non-TCA cycle pathways which we are currently exploring more deeply. HL-116264, HL-151587 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Additional effects of diosmin in the treatment of arterial hypertension in patients with impaired renal venous blood flow

Objective: to estimate of the effect of diosmin in complex antihypertensive therapy on renal function in patients with hypertension and impaired renal venous blood flow.Materials and methods: we observed 147 patients with hypertension aged 40.86±8.27 with signs of bilateral impairment of venous blood flow in the kidneys, which, depending on the amount of therapy, were divided into 2 groups and 2 subgroups. The comparison group consisted of 57 AH patients with unchanged venous blood flow in both kidneys.Results: in the presence of impaired venous blood flow in the renal veins, the use of additional administration of diosmin allows maintaining or improving the filtration capacity of the kidneys. Additional monitoring of patients with impaired venous blood flow in the kidneys is required to assess the effectiveness of antihypertensive therapy with individual drugs with and without venoactive agents.Conclusion: the additional inclusion of diosmin in the complex antihypertensive therapy of patients with arterial hypertension and impaired venous blood flow to the kidneys can preserve and improve kidney function with normalization of GFR.

RENAL EXTRACTION EFFICIENCY FOR PAH IS COMPARABLE IN ESSENTIAL HYPERTENSION AND RENAL FIBROMUSCULAR DYSPLASIA

Objective: Previously, we demonstrated that intrarenal blood flow in most patients with renal fibromuscular dysplasia (FMD) does not differ from that of patients with essential hypertension and patent renal arteries. In the present study, we assessed whether the renal extraction of para-aminohippurate (PAH) as a marker of tubular function was affected by the presence of FMD. Design and method: We studied 136 hypertensive patients who were scheduled for diagnostic renal angiography with arterial and renal venous blood sampling. In all of them, a continuous infusion of PAH was started two hours before the procedure to obtain steady state plasma levels at the time of sampling. Blood was collected simultaneously from the arterial and venous catheter prior to the administration of contrast material. Mean renal blood flow (MRBF) was measured simultaneously using the 133Xenon washout technique. Results: Altogether, 21 patients were diagnosed with renal FMD, 45 with atherosclerotic renal artery stenosis (ARAS) and 70 with essential hypertension (EH). Extraction ratio of PAH (ER-PAH) in the patients with renal FMD averaged 72 + 4% which did not differ significantly from that in patients with EH (74 + 3%). MBRF did not differ between these two groups either. Per contra, in patients with ARAS both MRBF and ER-PAH were significantly lower as compared to the other groups. ER-PAH in FMD patients was not modified by age, sex, height of blood pressure or MBRF. Conclusions: The ER of PAH in patients with renal FMD does not differ from that in EH. Thus, both flow and tubular function are well preserved in FMD when is EH is taken as control. This suggests that the pathophysiological mechanism which contribute to hypertension in FMD are different from those which are active in ARAS.

Changes in Oxygen Consumption and Metabolomic Profiles in the Kidney of Sprague‐Dawley Rat fed a High‐Salt Diet

The metabolism of oxygen and substrates in the kidney under normal conditions and in salt‐sensitive hypertension is still not well understood. A novel method was developed to collect renal arteriovenous blood and urine from conscious freely moving rats, while measuring renal blood flow (RBF) and blood pressure (BP). As such, global renal O2 consumption and metabolic profiles can be studied in response to various stimuli such as changes in salt diet. We report here changes observed in male Sprague‐Dawley rats (SD; 10 wk age) before and after 21 days switching from a 0.4% NaCl (LS) diet to a 4.0% NaCl diet (HS). Rats were surgically instrumented with a renal ultrasonic artery flow probe (Transonic), a femoral arterial catheter, and a renal venous catheter and placed in a movement response caging system. After 7 days recovery, control levels of RBF and BP (24 hr/day) were obtained, and arterial and renal venous blood were sampled. Rats were then switched to the HS diet and blood sampled at days 7, 14 and 21 while RBF and BP were recorded continuously throughout the study. Blood O2 content was measured by radiometer immediately after blood collection and plasma samples frozen for global metabolomic analysis by the Jackson laboratory. The metabolomic analysis (Thermo Q‐Exactive Orbitrap coupled to a Vanquich UPLC system) was performed in 4 modes (C18 positive, C18 negative, HILIC positive and HILIC negative). Average 24 hr mean arterial pressure (MAP) of the SD rats increased slightly over the 21 days of the HS diet from 111 ± 2 to 119 ± 5 mmHg (p<0.05; n=7). Average 24 hr RBF rose from 9.2 ± 0.6 to 11.7 + 0.6 ml/min (p<0.05). O2 consumption increased significantly from 0.17 ± 0.03 to 0.26 ± 0.03 ml/min (p<0.05) as did O2 extraction which increased from 10.8 ± 1.1 % to 15.0 ± 1.2 % by Day 21 of HS diet. Of a total 1205 named metabolites detected, we present here those that differed between arterial and renal venous blood by more than 2‐fold and significantly (p<0.05; Benjamini‐Hochberg corrected). At the time of this report, in rats fed the LS diet, 33 compounds were found more abundant in arterial blood than in venous blood. 10 compounds were found more abundant in venous blood. The HS diet increased the arterial / venous ratio of some compounds progressively throughout the 21 days while others decreased. No evidence of anaerobic respiration was obtained with lactate, pyruvate, glutamate and TCA cycle related metabolites remaining unchanged throughout the study. Interestingly, some gut microbiome generated compounds were found to differentially altered by the HS diet. Despite no changes in arterial concentrations, a progressive reduction was observed in Triethylamine in the renal venous blood at each time point, while a progressive elevation was observed in Hexanoic acid. Venous levels of Cis‐4‐Decenedioic acid and Succinylacetone, known to be altered in some metabolic diseases were significantly increased by the HS diet. Urine measurements and cortical and outer medullary tissue measurements are currently under way which together with the RBF will enable calculation of metabolic fluxes of these various metabolites. We conclude that a high‐salt diet increases oxygen consumption and alters the metabolomic profiles of the kidney.

Exosomes from miR-374a-5p-modified mesenchymal stem cells inhibit the progression of renal fibrosis by regulating MAPK6/MK5/YAP axis

ABSTRACT Chronic kidney disease (CKD) in clinical is defined as a gradual loss of kidney function for more than 3 months. The pathologic course of CKD is characterized by extensive renal fibrosis; thus, preventing renal fibrosis is vital for the treatment of CKD. It has been reported that microRNA (miR)-374a-5p was under-expressed in renal venous blood samples from patients with CKD. In addition, it exhibited anti-apoptotic effects in renal tissues suggesting that miR-374a-5p may play an important role in CKD. However, it is not clear whether miR-374a-5p could be delivered to renal cells by exosomes and exerts anti-renal fibrosis effects. To mimic renal fibrosis in vitro, human renal tubular epithelial cell lines (HK-2 cells) were treated by transforming growth factor-β (TGF-β) 1. Reverse transcription-quantitative polymerase-chain reaction (RT-qPCR) or Western blot was carried out to evaluate the mechanism by which miR-374a-5p regulated the development of renal fibrosis. Next, exosomes were isolated using with ultracentrifugation method, and the relationship between miR-374a-5p and MAPK6 was evaluated using dual-Luciferase a reporter assay system. The results indicated TGF-β1 significantly down-regulated the expression of miR-374a-5p in HK-2 cells and miR-374a-5p agomir remarkably inhibited the progression of fibrosis in vitro. In addition, exosomal miR-374a-5p could be internalized by HK-2 cells and obviously enhanced the level of miR-374a-5p in HK-2 cells. Furthermore, exosomal miR-374a-5p prevented the progression of renal fibrosis in vivo by regulating MAPK6/MK5/YAP axis. In conclusion, exosomal miR-374a-5p inhibited the progression of renal fibrosis by regulating MAPK6/MK5/YAP axis.

Neutrophil gelatinase-associated lipocalin does not originate from the kidney during reperfusion in clinical renal transplantation

BackgroundAcute Kidney Injury (AKI) is a common clinical complication. Plasma/serum neutrophil gelatinase-associated lipocalin (NGAL) has been proposed as a rapid marker of AKI. However, NGAL is not kidney-specific. It exists in three isoforms (monomeric, homo-dimeric and hetero-dimeric). Only the monomeric isoform is produced by renal tubular cells and plasma NGAL levels are confounded by the release of all NGAL isoforms from neutrophils. Our aim was to investigate whether NGAL is released into blood from injured renal tubules.MethodsKidney transplantation (n = 28) served as a clinical model of renal ischaemic injury. We used ELISA to measure NGAL concentrations at 2 minutes after kidney graft reperfusion in simultaneously taken samples of renal arterial and renal venous blood. Trans-renal gradients (venous–arterial) of NGAL were calculated. We performed Western blotting to distinguish between renal and non-renal NGAL isoforms. Liver-type fatty acid binding protein (LFABP) and heart-type fatty acid binding protein (HFABP) served as positive controls of proximal and distal tubular damage.ResultsSignificant renal release of LFABP [trans-renal gradient 8.4 (1.7–30.0) ng/ml, p = 0.005] and HFABP [trans-renal gradient 3.7 (1.1–5.0) ng/ml, p = 0.003] at 2 minutes after renal graft reperfusion indicated proximal and distal tubular damage. NGAL concentrations were comparable in renal venous and renal arterial blood. Thus, there was no trans-renal gradient of NGAL. Western blotting revealed that the renal NGAL isoform represented only 6% of the total NGAL in renal venous blood.ConclusionsIschaemic proximal and distal tubular damage occurs in kidney transplantation without concomitant NGAL washout from the kidney graft into blood. Plasma/serum NGAL levels are confounded by the release of NGAL from neutrophils. Present results do not support the interpretation that increase in plasma NGAL is caused by release from the renal tubules.

Abstract 41: Changes In Renal Oxygen Consumption With High-salt Diet Differ Between Sprague Dawley And Dahl Salt Sensitive Rats.

It has appeared evident that blood flow to the renal cortex which is required for glomerular filtration far exceeds the delivery of O 2 required for tubular metabolic needs. Yet, the metabolic needs of kidneys are second only to the heart per gram tissue and changes in O 2 extraction and utilization have not been directly measured in face of enhanced workloads such those imposed by high salt (HS) diets. We have developed techniques enabling continuous 24 hr/d monitoring of renal blood flow (RBF; Transonic flow probe) together with blood pressure (BP, 24hr/d) and intermittent sampling of arterial and renal venous blood over 21 days. O 2 content (mL/dL) was determined as 1.31 х Hemoglobin (Hb) (g/dL) х HbO 2 (%) + 0.003 х PaO 2 (mmHg); O 2 consumption (ml/min) was determined as RBF (ml/min) х (arterial-renal venous O 2 content difference). Sprague Dawley rats (SD; n=7; 10 wk age) were compared to Dahl salt-sensitive (SS; n=6; 8 wk age) rats fed 0.4% NaCl and during the 21 days of 4.0% NaCl (HS) diet. Beginning 7 days following surgery, RBF and BP were recorded 24 hr/day, and arterial and renal venous blood sampled for determination of blood gases (ABL800 FLEX radiometer) at 7, 14 and 21 of the HS diet. Average 24 hr mean BP of SD rats increased with the HS diet from 111±2 to 119±5 mmHg and SS rats rose from 121±5 to 155±9 mmHg (p<0.05); average 24 hr RBF of SD rats rose from 9.2±0.6 to 11.7 + 0.6 ml/min (p<0.05) while SS rats exhibited little change (7.0±0.6 to 7.0 + 0.9). RBF when expressed per gram kidney weight (gkw; determined in separate groups of rats) remained unchanged in both SD and SS rats in response to the HS diet. SS rats exhibited lower levels of RBF gkw than SD rats (p<0.05). Expressed either as absolute values or gkw, O 2 extraction and consumption was increased significantly in SD rats but not SS rats fed the HS diet. The results of the study indicate that despite high levels of RBF per tissue weight, increased metabolic work imposed by a HS diet resulted in a significant increase of RBF, O 2 extraction and consumption in normal rats. In contrast, SS rats exhibited lower levels of RBF but failed to increase either O 2 delivery or extraction. This failure may contribute importantly to altered metabolic substrate utilization in SS rats fed a HS diet, progression of ischemic related injury and hypertension.

High Salt Diet Increases Renal Oxygen Consumption in Sprague‐Dawley Rats

The physiological relationships between kidney O2 delivery and consumption and metabolism have been studied only under conditions of anesthesia and stressful surgical procedures. We report here techniques developed in our laboratory enabling determination of kidney O2 utilization over many days in instrumented unanesthetized rats in which the effects of a high salt diet were determined in normal Sprague Dawley (SD) rats. Male SD rats (10 weeks of age) fed a 0.4% NaCl diet were instrumented with a left renal artery flow probe (Transonic) for continuous (24 hr/day) measurement of renal blood flow (RBF). An indwelling intra-renal vein catheter (MRE 025) was inserted through the femoral vein and tip fixed close to the renal pelvis. An aortic catheter inserted though the femoral artery was implanted to sample blood and continuously (24 hr/day) measure arterial blood pressure (BP). Catheters and flow probe cables which exited from the neck were attached to a custom designed swivel and a servo-controlled circular cage system (BASi cage) enabling the rat to move freely throughout the study. Following 7 days of recovery from surgery, continuous monitoring of RBF and BP began and continued throughout the study. Following a 3 day control period with rats fed a 0.4% NaCl diet, renal venous and arterial blood were samples (250 ul) and blood gas was measured immediately by a radiometer (ABL800 FLEX). The diet was switch to 4% NaCl and blood sampling was performed at days 7, 14 and 21 of the high salt diet. O2 content, O2 consumption, and O2 extraction were determined as: O2 content (mL/dL): 0.31 × Hemoglobin (Hb) (g/dL) × HbO­2 (%) + 0.003 × PaO2 (mmHg). O2 consumption (ml/min): RBF (ml/min) × (arterial-renal venous O2 content difference). O2 extraction (% of arterial supply): 1-(renal venous O2 content/arterial O2 content) × 100. Daily average mean arterial pressure (MAP) increased moderately soon after switching to the 4% NaCl diet from 113 ± 2 to 120 ± 2 mmHg by day 3 (p=0.03, n=9) and remain elevated at this level throughout the study (120 ± 3 mmHg at day 13). Renal blood flow also rose soon after switching to the 4% salt diet from 9.4 ± 0.8 to 10.3 ± 0.8 ml/min during day 2 (p=0.03, n=9) . Thereafter, it also remained elevated throughout the study (10.7 ± 0.8 ml/min at day 13). Changes in O2 consumption occurred more gradually increasing from 0.21 ± 0.04 and rising to 0.27 ± 0.03 (ml/min) at day 14 of 4% salt diet (p=0.02, n=5). The calculated O2 extraction ratio remained unchanged ranging from 12.1 ± 0.1 (%) to 12.8 ± 0.1 (%) (p=0.48, n=5) throughout the study. It appears that in normal SD rats, the increased tubular metabolic work associated with a high salt diet is initially accommodated by increased perfusion (RBF) and a gradual increase of O2 consumption while extraction remains unchanged for a two-week period.