Renal Filtration Research Articles

Novel clearance of muscle proteins by muscle cells

Blood levels of cardiac troponins (cTn) and myoglobin are analysed when myocardial infarction (MI) is suspected. Here we describe a novel clearance mechanism for muscle proteins by muscle cells. The complete plasma clearance profile of cTn and myoglobin was followed in rats after intravenous or intermuscular injections and analysed by PET and fluorescence microscopy of muscle biopsies and muscle cells. Compared with intravenous injections, only 5 % of cTnT, 0.6 % of cTnI and 8 % of myoglobin were recovered in the circulation following intramuscular injection. In contrast, 47 % of the renal filtration marker FITC-sinistrin and 81 % of cTn fragments from MI-patients were recovered after intramuscular injection. In addition, PET and biopsy analysis revealed that cTn was taken up by the quadriceps muscle and both cTn and myoglobin were endocytosed by cultured muscle cells. This local clearance mechanism could possibly be the dominant clearance mechanism for cTn, myoglobin and other muscle damage biomarkers released by muscle cells.

On-demand degradable magnetic resonance imaging nanoprobes

Theranostic nanoprobes can potentially integrate imaging and therapeutic capabilities into a single platform, offering a new personalized cancer diagnostic tool. However, there is a growing concern that their clinical application is not safe, particularly due to metal-containing elements, such as the gadolinium used in magnetic resonance imaging (MRI). We demonstrate for the first time that the photothermal melting of the DNA duplex helix was a reliable and versatile strategy that enables the on-demand degradation of the gadolinium-containing MRI reporter gene from polydopamine (PDA)-based theranostic nanoprobes. The combination of chemotherapy (doxorubicin) and photothermal therapy, which leads to the enhanced anti-tumor effect. In vivo MRI tracking reveals that renal filtration was able to rapidly clear the free gadolinium-containing MRI reporter from the mice body. This results in a decrease in the long-term toxic effect of theranostic MRI nanoprobes. Our findings may pave the way to address toxicity issues of the theranostic nanoprobes.

Recovery of Renal Function following Kidney-Specific VEGF Therapy in Experimental Renovascular Disease

Background: Chronic renovascular disease (RVD) can lead to a progressive loss of renal function, and current treatments are inefficient. We designed a fusion of vascular endothelial growth factor (VEGF) conjugated to an elastin-like polypeptide (ELP) carrier protein with an N-terminal kidney-targeting peptide (KTP). We tested the hypothesis that KTP-ELP-VEGF therapy will effectively recover renal function with an improved targeting profile. Further, we aimed to elucidate potential mechanisms driving renal recovery. Methods: Unilateral RVD was induced in 14 pigs. Six weeks later, renal blood flow (RBF) and glomerular filtration rate (GFR) were quantified by multidetector CT imaging. Pigs then received a single intrarenal injection of KTP-ELP-VEGF or vehicle. CT quantification of renal hemodynamics was repeated 4 weeks later, and then pigs were euthanized. Ex vivo renal microvascular (MV) density and media-to-lumen ratio, macrophage infiltration, and fibrosis were quantified. In parallel, THP-1 human monocytes were differentiated into naïve macrophages (M0) or inflammatory macrophages (M1) and incubated with VEGF, KTP-ELP, KTP-ELP-VEGF, or control media. The mRNA expression of macrophage polarization and angiogenic markers was quantified (qPCR). Results: Intrarenal KTP-ELP-VEGF improved RBF, GFR, and MV density and attenuated MV media-to-lumen ratio and renal fibrosis compared to placebo, accompanied by augmented renal M2 macrophages. In vitro, exposure to VEGF/KTP-ELP-VEGF shifted M0 macrophages to a proangiogenic M2 phenotype while M1s were nonresponsive to VEGF treatment. Conclusions: Our results support the efficacy of a new renal-specific biologic construct in recovering renal function and suggest that VEGF may directly influence macrophage phenotype as a possible mechanism to improve MV integrity and function in the stenotic kidney.

Microvascular dysfunction and kidney disease: Challenges and opportunities?

Kidneys are highly vascular organs that despite their relatively small size receive 20% of the cardiac output. The highly intricate, delicately organized structure of renal microcirculation is essential to enable renal function and glomerular filtration rate through the local modulation of renal blood flow and intraglomerular pressure. Not surprisingly, the dysregulation of blood flow within the microvessels (abnormal vasoreactivity), fibrosis driven by disordered vascular-renal cross talk, or the loss of renal microvasculature (rarefaction) is associated with kidney disease. In addition, kidney disease can cause microcirculatory dysfunction in distant organs such as the heart and brain, mediated by mechanisms that remain to be elucidated. The objective of this review is to highlight the role of renal microvasculature in kidney disease. The overview will outline the impetus to study renal microvasculature, the bidirectional relationship between kidney disease and microvascular dysfunction, the key pathways driving microvascular diseases such as vasoreactivity, the cell dynamics coordinating fibrosis, and vessel rarefaction. Finally, we will also briefly highlight new therapies targeting the renal microvasculature to improve renal function.

Clinical laboratory diagnosis of obstructive megaureter in children

Introduction. Currently, there are more than 200 methods of surgical treatment of a megaureter, but none of the methods has achieved universal acceptance. Until now, the issues of differential diagnosis of organic and functional causes of ureteral dilatation in children under 3 years of age have not been sufficiently illuminated, there is no generally accepted algorithm for the management of patients with this pathology.
 Relevance. The relevance of obstructive uropathies is evidenced by the fact that they occupy the third position in the list of the most common causes of chronic kidney disease in children, and account for 15% of cases. The prognosis of the outcome of obstructive uropathy is determined by the nature of the lesion and the degree of involvement in the pathological process of the kidneys, one of the main homeostatic and endocrine organs in humans. The degree of involvement of various markers in the development and progression of kidney damage in children is still insufficiently understood. All this prompts the search for screening, highly sensitive and specific methods for the diagnosis and prediction of nephrosclerotic changes in children against the background of urinary tract obstruction.
 Objective: The study of the clinical and laboratory diagnostic methods, allowing to differentiate functional or organic urodynamic disorders, to determine the tactics of managing patients with obstructive uropathy.
 Materials and methods. Since 2016, a study has been conducted of 174 children aged 0 to 18 years. 3 groups of children were identified: 1) with endoscopic treatment (main group); 2) treated with an open surgical method (control group); and 3) a group of children without urinary tract obstruction (reference group).
 Results. In the course of the study, it was found that the most optimal values of serum cystatin C, close to the reference group (0.048-0.831 mg/ml) were obtained in children treated with endoscopic correction of the intramural ureter (0.217-0.798 mg/ml).
 Conclusions. The tactics of endoscopic treatment of obstructive uropathies in children has advantages in terms of open surgical methods in technical simplicity, minimally invasiveness, maximum physiology, and a decrease in the frequency of postoperative complications. These theses are confirmed by the obtained results of the study of serum cystatin C as a marker of the state of renal filtration. It should be remembered that the effectiveness of endoscopic stenting of the lower ureter depends on the age of the child.

Dynamics of innate immunity parameters in acute kidney injury after coronary artery bypass grafting

Acute kidney injury (AKI) developing after cardiac surgery remains unsolved issue despite the high level of surgical techniques as well as organ and tissue protection during artificial blood circulation. Various publications demonstrate that complications emerge in as many as 42% cases, whereas renal replacement therapy is required in up to 1-8% cases. Systemic inflammatory response syndrome and activation of the blood coagulation system largely underlie developing AKI finally resulting in acute renal failure. Release of large amounts of cytokines is associated with subclinical renal damage, primarily with blocking renal glomerular filtration. Measuring concentration of serum inflammatory markers that could reflect activity of inflammatory events is crucial for predicting and selecting treatment methods as well as for identifying predictors of severe course with opportunity of early onset renal replacement therapy after hospitalization. Objective of our study was to assess diagnostic and prognostic value of innate immunity parameters such as interleukin (IL) 6, 8, 10, 17, tumor necrosis factor alpha (TNFα), growth factor TGF-β1 in patients with acute kidney injury before and after CABG. Blood serum samples collected from 120 patients (males and females) with ischemic heart disease (IHD) were examined before and after CABG. It was found that patients with acute kidney injury had elevated serum level of cytokines IL-6, IL-8, IL-10, IL-17, TNFα, and TGF-β1 in all groups on day 1 and day 2 after surgery. Hence, we provided the data on more detailed investigation of immune alterations in cardiosurgical patients with AKI prepared for planned CABG.

A Frequency-Selective pH-Responsive paraCEST Agent.

Paramagnetic chemical exchange saturation transfer (paraCEST) agents are well-suited for imaging tissue pH because the basis of CEST, chemical exchange, is inherently sensitive to pH. Several previous pH-sensitive paraCEST agents were based on an exchanging Ln3+ -bound water molecule as the CEST antenna but this design often added additional line-broadening to the bulk water signal due to T2 exchange. We report herein a pH-sensitive paraCEST agent that lacks an inner-sphere water molecule but contains one Ln-bound -OH group for CEST activation. The Yb3+ complex, Yb(1), displayed a single, highly shifted CEST peak originating from the exchangeable Yb-OH proton, the frequency of which changed over the biologically relevant pH range. CEST images of phantoms ranging in pH from 6 to 8 demonstrate the potential of this agent for imaging pH. Initial rodent imaging studies showed that Gd(1) remains in the vascular system much longer than anticipated but is cleared slowly via renal filtration.

A Frequency‐Selective pH‐Responsive paraCEST Agent

AbstractParamagnetic chemical exchange saturation transfer (paraCEST) agents are well‐suited for imaging tissue pH because the basis of CEST, chemical exchange, is inherently sensitive to pH. Several previous pH‐sensitive paraCEST agents were based on an exchanging Ln3+‐bound water molecule as the CEST antenna but this design often added additional line‐broadening to the bulk water signal due to T2 exchange. We report herein a pH‐sensitive paraCEST agent that lacks an inner‐sphere water molecule but contains one Ln‐bound −OH group for CEST activation. The Yb3+ complex, Yb(1), displayed a single, highly shifted CEST peak originating from the exchangeable Yb‐OH proton, the frequency of which changed over the biologically relevant pH range. CEST images of phantoms ranging in pH from 6 to 8 demonstrate the potential of this agent for imaging pH. Initial rodent imaging studies showed that Gd(1) remains in the vascular system much longer than anticipated but is cleared slowly via renal filtration.

Serum pre-albumin is prognostic for all-cause mortality in patients with community-acquired and post-operative acute kidney injury.

Acute kidney injury (AKI) is a critical clinical syndrome characterised by a rapid decrease in renal filtration, with the accumulation of products of metabolism such as creatinine and urea. In recent years, the incidence of AKI has increased not only in critically ill hospitalised patients but also in community patients. Also, the prognosis of AKI is poor and treatment is limited in these populations. The increasing incidence and poor prognosis may be the reasons why more investigators are involved in epidemiological and risk factor analysis of AKI. To investigate the effects of these risk factors on outcomes in both community-acquired and hospitalised AKI populations to provide certain guidance for clinics and to explore the prognostic value of prealbumin on all-cause mortality in patients with community-acquired and post-operative AKI. From 2000 to 2010, 477 patients diagnosed with AKI and treated in the Department of Nephrology, Ruijin Hospital, Shanghai Jiaotong University, were enrolled in the community-acquired AKI (CA-AKI) group and 138 patients diagnosed with AKI after an operation were enrolled in the post-operative AKI (PO-AKI) group. Data were collected at AKI onset and 1 year after discharge and analysed retrospectively. Compared with PO-AKI patients, more patients in CA-AKI group had chronic kidney disease, obesity and hyperlipidaemia, and fewer patients had cerebrovascular disease (CVD), anaemia, shock or arrhythmia. Risks for CA-AKI were atherosclerosis, CVD, arrhythmia, multiple organ dysfunction syndrome and usage of vasoactive agents, and risks for PO-AKI were elderly, arrhythmia and requirement of renal replacement therapy. A higher level of serum PA was associated with a better outcome in the CA-AKI group (hazard ratio 0.92, 95% confidence interval 0.85-0.996) and PO-AKI group (hazard ratio 0.91, 95% confidence interval 0.84-0.99). In the CA-AKI group, the cumulative survival rate of patients with a normal PA level (PA >20 mg/dL) was higher than that among patients with a lower PA (PA ≤20 mg/dL; 95.4% vs 88.3%, P = 0.031). Similarly, in the PO-AKI group, a normal PA level was associated with a higher survival rate (74.1% vs 47.6%, P = 0.019). Serum PA may serve as a prognostic marker for CA-AKI and PO-AKI, and further research is warranted to confirm this finding.

Acute Kidney Injury in Patients of Emergency and Surgical Intensive Care Units: Incidence and Risk Factors

Background: Acute kidney injury is an abrupt or rapid decline in renal filtration function. Objective: The study aimed to identify the incidence and analyze the risk factors (age and sex) for acute kidney injury development in patients of emergency and surgical intensive care units. Patients and Methods: This study was carried out at emergency and surgical intensive care units of Zagazig University Hospitals over a period of 6 months. Data collection were1: Peak of serum creatinine level. 2: Peak of decreased urine output. 3: At the peak of AKI: AKIN (Acute Kidney Injury Network) score. Results: Incidence of AKI in patients with normal kidney functions at admission and without history of any previous renal problems equal 7.015% according to AKIN score. Conclusion: our results reported that incidence rate of developing AKI in patients of emergency and postoperative critical care units along the period of 6 months according to the inclusion criteria and AKIN score is 7.015 %. Age and sex weren’t risk factors for AKI.

Evaluation of the pharmacokinetic drug-drug interaction potential of iohexol, a renal filtration marker.

Carboplatin dose is calculated based on kidney function, commonly estimated with imperfect creatinine-based formulae. Iohexol is used to measure glomerular filtration rate (GFR) and allows calculation of a more appropriate carboplatin dose. To address potential concerns that iohexol administered during a course of chemotherapy impacts that therapy, we performed in vitro and in vivo pharmacokinetic drug-drug interaction evaluations of iohexol. Carboplatin was administered IV to female mice at 60mg/kg with or without iohexol at 300mg/kg. Plasma ultrafiltrate, kidney and bone marrow platinum was quantitated by atomic absorption spectrophotometry. Paclitaxel microsomal and gemcitabine cytosolic metabolism as well as metabolism of CYP and UGT probes was assessed with and without iohexol at 300µg/mL by LC-MS/MS. In vivo carboplatin exposure was not significantly affected by iohexol co-administration (platinum AUC combination vs alone: plasma ultrafiltrate 1,791 vs 1920µg/mL min; kidney 8367 vs 9757µg/g min; bone marrow 12.7 vs 12.7µg/mg-protein min). Paclitaxel microsomal metabolism was not impacted (combination vs alone: 6-α-OH-paclitaxel 38.3 versus 39.4ng/mL/60min; 3-p-OH-paclitaxel 26.2 versus 27.7ng/mL/60min). Gemcitabine human cytosolic elimination was not impacted (AUC combination vs gemcitabine alone: dFdU 24.1 versus 23.7µg/mL/30min). Iohexol displayed no relevant inhibition of the CYP and UGT enzymes in human liver microsomes. Iohexol is unlikely to affect the clinical pharmacokinetics of carboplatin, paclitaxel, gemcitabine, or other agents used in combination with carboplatin treatment. Measuring GFR with iohexol to better dose carboplatin is unlikely to alter the safety or efficacy of chemotherapy through pharmacokinetic drug-drug interactions.

The Renal Extraction and the Natriuretic Action of GLP-1 in Humans Depend on Interaction With the GLP-1 Receptor.

The natriuretic effect of glucagon-like peptide-1 (GLP-1) in humans is independent of changes in renal plasma flow (RPF) and glomerular filtration rate (GFR) but may involve suppression of angiotensin II (ANG II) and a significant (~45%) renal extraction of GLP-1. The current study was designed to investigate the consequences for the renal extraction and the natriuretic effect of blocking GLP-1 receptors with the specific GLP-1 receptor antagonist, Exendin 9-39 (Ex 9-39). Under fixed sodium intake for 4 days before each study day, 6 healthy male participants were recruited from our recent study where GLP-1 or vehicle was infused (1). In the present new experiments, participants were examined during a 3-hour infusion of GLP-1 (1.5 pmol/kg/min) together with a 3.5-hour infusion of Ex 9-39 (900 pmol/kg/min). Timed urine collections were conducted throughout the experiments. Renal extraction of GLP-1 as well as RPF and GFR were measured via Fick's principle after catheterization of a renal vein. Arterial plasma renin, ANG II, and aldosterone concentrations were measured. Co-infusion of Ex 9-39 significantly reduced renal extraction of GLP-1 to ~25% compared with GLP-1 infusion alone (~45%). Urinary sodium excretions remained at baseline levels during co-infusion of Ex 9-39 as well as vehicle. By contrast, GLP-1 infusion alone resulted in a 2-fold increase in natriuresis. Ex 9-39 abolished the GLP-1-induced decrease in arterial ANG II concentrations. RPF and GFR remained unchanged during all experiments. Renal extraction of GLP-1 and its effect on natriuresis are both dependent on GLP-1 receptor activation in healthy humans.

Hepatorenal syndrome: pathophysiology, diagnosis, and management

Hepatorenal syndrome (HRS), the extreme manifestation of renal impairment in patients with cirrhosis, is characterized by reduction in renal blood flow and glomerular filtration rate. Hepatorenal syndrome is diagnosed when kidney function is reduced but evidence of intrinsic kidney disease, such as hematuria, proteinuria, or abnormal kidney ultrasonography, is absent. Unlike other causes of acute kidney injury (AKI), hepatorenal syndrome results from functional changes in the renal circulation and is potentially reversible with liver transplantation or vasoconstrictor drugs. Two forms of hepatorenal syndrome are recognized depending on the acuity and progression of kidney injury. The first represents an acute impairment of kidney function, HRS-AKI, whereas the second represents a more chronic kidney dysfunction, HRS-CKD (chronic kidney disease). In this review, we provide critical insight into the definition, pathophysiology, diagnosis, and management of hepatorenal syndrome.

Evaluation of designs for renal drug studies based on the European Medicines Agency and Food and Drug Administration guidelines for drugs that are predominantly secreted.

Dose adjustment for drugs eliminated by the kidneys generally assume a linear relationship between renal drug clearance (CLR ) and glomerular filtration rate (GFR). This assumption may not hold for drugs that undergo extensive tubular secretion where nonlinearity in drug handling is expected. The aim of this study is to determine if renal drug study designs recommended by the European Medicines Agency (EMA) and Food and Drug Administration (FDA) could distinguish linear from nonlinear renal drug handling. In this simulation and estimation study, the study designs based on the EMA and FDA guidelines for Phase I renal drug studies were evaluated for their ability to discriminate a linear from a nonlinear relationship between CLR and GFR. The number of subjects for each simulated study ranged from 4 to 960. Power, relative standard error and bias were calculated. Study designs under the EMA and FDA guidelines required ≥8 and ≥48 subjects, respectively, to achieve ≥80% power to discriminate a linear from nonlinear relationship between CLR and GFR. The relative standard error of estimated parameters were 13-37 and 17-44% for the designs with 24 subjects under the EMA and FDA guidelines, respectively. The bias in parameter estimates under the EMA designs were not evident, however, they were biased (13-21%) under the FDA designs. The EMA design was found to require fewer subjects (n = 8) compared to the FDA (n = 48) to discriminate linear from nonlinear drug renal handling at ≥80% study power while both the designs perform poorly for the parameter precision.

RNA Nanoparticles as Rubber for Compelling Vessel Extravasation to Enhance Tumor Targeting and for Fast Renal Excretion to Reduce Toxicity.

Rubber is a fascinating material in both industry and daily life. The development of elastomeric material in nanotechnology is imperative due to its economic and technological potential. By virtue of their distinctive physicochemical properties, nucleic acids have been extensively explored in material science. The Phi29 DNA packaging motor contains a 3WJ with three angles of 97°, 125°, and 138°. Here, the rubber-like property of RNA architectures was investigated using optical tweezers and in vivo imaging technologies. The 3WJ 97° interior angle was contracted or stretched to 60°, 90°, and 108° at will to build elegant RNA triangles, squares, pentagons, cubes, tetrahedrons, dendrimers, and prisms. RNA nanoarchitecture was stretchable and shrinkable by optical tweezer with multiple extension and relaxation repeats like a rubber. Comparing to gold and iron nanoparticles with the same size, RNA nanoparticles display stronger cancer-targeting outcomes, while less accumulation in healthy organs. Generally, the upper limit of renal excretion is 5.5 nm; however, the 5, 10, and 20 nm RNA nanoparticles passed the renal filtration and resumed their original structure identified in urine. These findings solve two previous mysteries: (1) Why RNA nanoparticles have an unusually high tumor targeting efficiency since their rubber or amoeba-like deformation property enables them to squeeze out of the leaky vasculature to improve the EPR effect; and (2) why RNA nanoparticles remain non-toxic since they can be rapidly cleared from the body via renal excretion into urine with little accumulation in the body. Considering its controllable shape and size plus its rubber-like property, RNA holds great promises for industrial and biomedical applications especially in cancer therapeutics delivery.

Long-term outcomes after pyeloplasty for pelvi-ureteric junction obstruction in adults associated with renal congenital anomalies: Age, sex and renal function matched analysis

ABSTRACT Objective: To assess the long-term outcomes after pyeloplasty for pelvi-ureteric junction obstruction (PUJO) associated with renal anomalies. Patients and methods: Data were collected for patients after pyeloplasty for PUJO associated with renal anomalies and analysed retrospectively. Long-term functional success was evaluated by comparing the renographic split renal function (SRF) and glomerular filtration rate (GFR) at last follow-up with baseline values. A change of 5% in SRF was considered significant. Factors affecting functional outcome were assessed. The outcomes were compared to an age, sex and renal function matched group with PUJO in otherwise normal kidneys (Group 2) to evaluate the pattern of difference in functional recoverability in both groups. This was assessed using repeated-measures analysis of variance. Results: The study initially included 70 adult patients, with a mean age of 31.8 years. At a median of 44 months, 55 patients completed follow-up (Group 1) and no statistically significant changes in GFR (P = 0.7) and SRF (P = 0.06) were found. In all, 17, four and 34 patients showed a decrease, increase and static SRF (functional success rate was 69%). Higher preoperative SRF (P = 0.02) and Anderson–Hynes (A–H) pyeloplasty (P = 0.003) were associated with functional preservation. In the comparison with the other matched group (Group 2), the patients in Group 2 had better functional recoverability after pyeloplasty than patients with associated anomalies [GFR (P = 0.001), SRF (P = 0.002) and functional success (P = 0.001)]. Conclusion: Functional preservation after pyeloplasty in associated renal anomalies could be achieved in 69% of patients, which was significantly lower than those with otherwise normal kidneys. A–H pyeloplasty and higher preoperative SRF were associated with better functional outcomes. Abbreviations: A–H: Anderson–Hynes; HSK: horseshoe kidneys; OR: odds ratio; PUJO: PUJ obstruction; SRF: split renal function; T1/2, half-time

Abstract P004: Endothelial Function In Rat Juxtamedullary Afferent Arterioles After Renal Ischemia-reperfusion Injury

Renal ischemia-reperfusion (IR) induced kidney injury exhibits reduced renal blood flow (RBF) and glomerular filtration rate (GFR). Both RBF and GFR are regulated by renal microvascular function. Our previous study showed that IR caused impaired afferent arteriole autoregulatory capability via excess ROS accumulation and inflammation in renal microvessels. Other mechanisms contributing to renal microvascular dysfunction in IR have not been fully defined. In this study, we conducted acetylcholine (ACh) concentration-response experiments (n=5-7/each group) to assess endothelial function using the in vitro blood-perfused juxtamedullary nephron preparation. IR was induced by 60 minutes of bilateral renal artery occlusion followed by 24 hours or 7 days of reperfusion. Renal microvessels (RMV) were collected at either 24 hours or 7 days post-surgery for mRNA analysis. Systolic blood pressure was normal in IR rats vs. sham ranging from 126-136 mmHg (>0.05) over 7 days. IR markedly increased plasma creatinine concentration (Cr) to 3.9±0.2 mg/dL at 24 hours post-IR ( P <0.05 vs. 0.9±0.1 mg/dL in sham). Plasma Cr remained elevated in IR rats by day 7 of reperfusion (1.5±0.2 vs. 1.0±0.0 mg/dL in sham, P <0.05). Baseline afferent arteriole diameter was smaller in IR rats 24 hours post-IR and averaged 11.1±0.7 μm (P<0.05 vs. 14.2±0.7 μm in sham). Superfusion of ACh (10 -8 to 10 -4 M) caused concentration-dependent vasodilation in sham rats, increasing diameter to 23.5±2.6 μm (169±14% of the control, P <0.05) at 10 -4 M ACh. The ACh-induced vasodilation was not altered by IR insult and was indistinguishable from the sham responses. IR diameter reached a maximum of 19.7±0.9 μm (179±8% of the control) at 10 -5 M ACh. The ACh responses were also similar between sham and IR rats on day 7 post-IR. mRNA expression of endothelial markers, iCAM and vCAM, were not statistically different in RMV collected at 24 hours post-surgery between two groups, but was markedly elevated in IR RMV on day 7 post-IR (4-fold in iCAM and 2-fold in vCAM, P<0.05 vs. sham). In conclusion, upregulation of iCAM and vCAM mRNA expression in RMV 7 days post-IR suggests renal microvascular inflammation, but rat juxtamedullary afferent arterioles still maintain normal endothelium-dependent reactivity to ACh.

Abstract P147: Attenuation Of Diuretic And Natriuretic Responses To Acute Saline Volume Expansion In Mice Pre-treated With Tumor Necrosis Factor-alpha (TNFα) Inhibitor, Etanercept.

High salt intake induces an immune response that activates the mononuclear phagocyte system (MPS) cells to produce TNFα. We have previously demonstrated that intravenous infusion of TNFα in mice induces diuresis and natriuresis by inhibiting renal tubular sodium reabsorption. We hypothesize that the intravenous saline infusion can also induce the production of TNFα from MPS cells and such increase in TNFα influences saline induced natriuresis in the kidney. To examine this hypothesis, we measured the changes in TNFα levels in plasma and in urinary excretion rate (U TNFα V) during intravenous infusion of isotonic saline (0.9% NaCl), first at euvolemic condition (3 μL/min for 60 min; Baseline period) and then at an enhanced infusion rate (12 μL/min for 90 min; Volume expansion period) in anesthetized mice (n=5). Renal blood flow (RBF) and glomerular filtration rate (GFR) were measured by PAH and inulin clearances respectively. TNFα concentration in plasma and urine samples were determined using ELISA kit (Ebioscience, Woburn, MA). TNFα level in plasma collected during baseline period was undetectable, however, TNFα was increased to 3.7±1.3 pg/mL during volume expansion (VE) period. Baseline U TNFα V level was 0.01±0.002 pg/min/g (kidney wt), which was increased to 0.11±0.03 pg/min/g (P<0.05) during VE period. VE increased urine flow (V, 5.4±0.5 to 22.0±5.1 μL/min/g; P<0.05) and sodium excretion (U Na V; 0.54±0.19 to 4.84 ±1.16 μmol/min/g; P<0.05) without significant changes in RBF (7.1±1.0 to 6.0±1.8 mL/min/g) and GFR (1.18±0.11 to 0.94±0.28 mL/min/g). Interestingly, the diuretic and natriuretic responses to VE were markedly attenuated in mice (n=5) pretreated with a TNFα inhibitor, etanercept (ETN; 0.5 mg/kg intraperitoneally once daily for 3 days prior to the experiment day). VE induced changes in ETN treated mice are as follows: V, 5.9±0.65 to 7.9 ±1.6 μL/min/g; U Na V, 0.43±0.6 to 1.1±0.28 μmol/min/g; RBF, 5.4±0.4 to 6.6±0.9 mL/min/g and GFR, 0.87±0.09 to 0.98±0.13 mL/min/g. These findings demonstrate for the first time that an intravenous saline volume infusion resulted an increase in TNFα level in plasma and in urine. These results strongly suggest a physiological role for TNFα in regulating renal excretory function during saline volume expansion.

Intrarenal Renin Angiotensin System Imbalance During Postnatal Life Is Associated With Increased Microvascular Density in the Mature Kidney.

Environmental stress during early life is an important factor that affects the postnatal renal development. We have previously shown that male rats exposed to maternal separation (MatSep), a model of early life stress, are normotensive but display a sex-specific reduced renal function and exacerbated angiotensin II (AngII)-mediated vascular responses as adults. Since optimal AngII levels during postnatal life are required for normal maturation of the kidney, this study was designed to investigate both short- and long-term effect of MatSep on (1) the renal vascular architecture and function, (2) the intrarenal renin-angiotensin system (RAS) components status, and (3) the genome-wide expression of genes in isolated renal vasculature. Renal tissue and plasma were collected from male rats at different postnatal days (P) for intrarenal RAS components mRNA and protein expression measurements at P2, 6, 10, 14, 21, and 90 and microCT analysis at P21 and 90. Although with similar body weight and renal mass trajectories from P2 to P90, MatSep rats displayed decreased renal filtration capacity at P90, while increased microvascular density at both P21 and P90 (p < 0.05). MatSep increased renal expression of renin, and angiotensin type 1 (AT1) and type 2 (AT2) receptors (p < 0.05), but reduced ACE2 mRNA expression and activity from P2-14 compared to controls. However, intrarenal levels of AngII peptide were reduced (p < 0.05) possible due to the increased degradation to AngIII by aminopeptidase A. In isolated renal vasculature from neonates, Enriched Biological Pathways functional clusters (EBPfc) from genes changed by MatSep reported to modulate extracellular structure organization, inflammation, and pro-angiogenic transcription factors. Our data suggest that male neonates exposed to MatSep could display permanent changes in the renal microvascular architecture in response to intrarenal RAS imbalance in the context of the atypical upregulation of angiogenic factors.

Pharmacokinetic Characterization to Enable Medicine Use in Pregnancy, the Potential Role of Physiologically-Based Pharmacokinetic Modeling: A Regulatory Perspective.

It is generally recommended that use of medicines should be avoided during pregnancy, sometimes however use of a medicine is essential to safeguard the health of mother and baby. A very limited number of medicines are however specifically licensed for use in pregnancy. This article considers the potential of PBPK modelling as a predictive tool to investigate the expected systemic exposure of medicines in pregnant women and to support possible dosing adjustment to maintain efficacy.