Tubular Water Research Articles

Application of Simple Crested Weirs to Control Outflows from Tiles Drainage

Triangular sharp-crested weirs are commonly used to measure low-flow measurements in open channels. The flow over such a V-notch is proportional to the height of water above the weir on the upstream side. Therefore, it is relatively easy to calculate the flow from standard equations by using only recordings of water levels. Thus, these types of weirs can provide inexpensive measurements of flow volumes and resulting nutrient loads from subsurface drainage systems and associated conservation practices. The objective of this study was to develop appropriate weir equations for a 22.5° V-notch weir developed for a new tubular water level control structure in a controlled drainage system (CD). Analyses using this weir, with three typical slope angles of 30°, 45°, and 60°, were also conducted. There were no significant differences in the fitted parameters across the three analyzed slope angles. The coefficient of determination (R2) values were 0.9955, 0.9981, and 0.9980, respectively. However, the best-fitted equation for a 22.5° V-notch weir was for a slope angle of 45°. The flow equation was Q = 0.2235H2.4182, with Q in liters per minute and H in centimeters. This equation can be used for measuring flow through tubular-controlled drainage structures.

Serum sodium as a diabetes risk factor?

Electrolytes play a key role in controlling fluid status, muscle contraction, neurological function, coagulation, and acid base status, as well as multiple enzymatic reactions. Diabetes is associated with multiple significant electrolyte disorders, predominantly affecting serum sodium (Na), potassium, and magnesium.1 In healthy individuals, serum Na levels range between 135–146 mmol/L. Hyponatremia is defined as a serum Na < 135 mmol/L, typically accompanied by a low serum osmolality (<275 mosm/L). It is the most frequently seen electrolyte disorder, present in about 5% of adults and 35% of hospitalized patients.2, 3 In a New York health system analysis of 10 385 patients hospitalized with COVID-19 in 2020, hyponatremia was present in 37.5% of patients.4 Low serum Na may activate the renin-angiotensin-aldosterone system, may cause increased sympathetic nervous system tone, and may be associated with oxidative stress. Insulin, either administered therapeutically or in the setting of hyperinsulinemia from insulin resistance, increases renal tubular water reabsorption via a presumed vasopressin effect and can result in hyponatremia. Chronic kidney disease and diuretic use in hypertension further increase the risk of hyponatremia as well as other electrolyte imbalances such as hypokalemia and hypomagnesemia.7 Serum Na simply may represent the state of hydration. Might some of these mechanisms contribute to effects of even small deviations in serum Na from normal? Should we look more carefully at Na as a biomarker of outcome? Further analysis of large clinical data sets may give answers to these questions.

Features of operation and hydraulic calculations

Issues related to the design and hydraulic calculations of the transit part of a closed tubular water supply structure of the siphon type are considered. The operating conditions of a siphon with rectangular pipes in the transition mode are estimated. Due to the formation of a hydraulic jump, the inlet section of the siphon pipes experiences increased hydrodynamic loads, leading to certain defects and destruction. The design of the siphon with two breaks along the length with a portal and a smooth inlet head or without it was modeled. As a result of modeling studies, the absence of a noticeable effect of the inlet head of the culvert on the length of the free-flow inlet section was established. It was revealed that the conditions of formation, the features of the hydraulic operation of the siphon, and the loads it experiences in the transient mode are largely determined by its design solutions. With the flooding of the inlet head, the flow of air into the pipe is hindered, and a transition mode of the second type is formed with a slight fluctuation in the water level in front of the structure upstream. The dependence of the location of the flow separation point with a decrease in the throughput of water on its value was revealed, which made it possible to obtain a graph of the dependence of the relative length of the free-flow section on the square root of the Froude number. A comparison was made with the results of studies by other authors, which showed an increase in the relative length in tubular structures of the siphon type in sections with reverse slopes at the same Froude numbers. Recommendations are given on the methodology for carrying out hydraulic calculation of tubular culverts for various purposes with minimal flow rates, and ways for further multifactorial studies of siphons on the reclamation network are indicated.

On the Heat Transfer of a Tubular Water–Water Heat Exchanger and Its Evaluation According to Some Criterial Models

On the Heat Transfer of a Tubular Water–Water Heat Exchanger and Its Evaluation According to Some Criterial Models

Experimental investigation of anion exchange membrane water electrolysis for a tubular microbial electrosynthesis cell design

Tubular water splitting electrolyzer was adapted to neutral pH conditions for the in-situ H2 supplying microbial electrosynthesis design. The electrolyzer was optimized to reduce ohmic losses and provide adequate gas separation. Direct membrane deposition was applied on a thin anionic exchange membrane for the membrane-electrode-assembly fabrication. Although the membrane resistance increased with the increasing membrane thickness from 55 to 165 μm, the contact resistance was reduced by applying stronger compression pressure on the membrane-electrode interface. A durability test was run for 120 h, showing a voltage increase of 134 μV/h. Moreover, the hydrogen permeability coefficient was determined at 10−14 mol/(mˑsˑPa).

Sampling bottles for shallow estuarine waters, constructed using inexpensive recyclable materials

Sampling water from shallow estuaries, rivers, or lakes, particularly where access is difficult, can be problematic. In estuaries at low tide, water depths can be less than a meter, and therefore conventional samplers based on vertical tubes of plastic or metal, such as Nansen and Niskin bottles, are inappropriate. During three consecutive years (2017–2019) whilst studying eutrophication in the shallow waters of the marginal Estero Salado (ES, Gulf of Guayaquil, Ecuador), a range of tubular water samplers were designed, constructed, and tested. Six of these designs are presented here and all use inexpensive recyclable and locally available materials. The sampling bottles were mainly made from readily available plastic components, including non-returnable drinking water bottles, acrylic/PVC pipes, tweezers, elastic bands, discarded gym weight plates, and closures made from plumbing items. Up to 80% of the materials used were recyclable. Costs ranged from 5 to 35 US$, and the time to design and construct was up to two days. The horizontal sampling bottles proved strong enough for rigorous field conditions. Sampling at depths <1 m, the bottles did not show any sign of collapsing due to either the hydrostatic pressure when empty nor the weight of the water sample. Three samplers are submerged with open ends to the depth required, and then moved sideways or allowed to align with the current to flush the interior. Then, a messenger or pulling on a line closes the bottle. A simple tap or direct dispensing is used to transfer the water into storage bottles. Two of the designs (with one end open) can be used to sample right through the very surface layer. Two of the designs that enter the water with closed ends were inter-compared with a standard Niskin water sampler and gave statistically comparable results. The lightest sampler was tested at various depths down to 5 m in a lake with no operational issues, and nutrient data from samples gave a coherent vertical profile. Two of the designs (with one end open) can be used to sample the very surface layer. The water samplers reported here are highly appropriate for laboratories with very limited resources and can be used in very shallow waters under a wide range of environmental conditions. Results from samples collected with the described samplers show that the inner estuarine branches of the ES are now under perennial hypoxic, acidic, and hypereutrophic conditions with extremely high total and fecal coliform loads.

Analysis Of the Effect of Flow Rate and Speed on Four Blade Tubular Water Bulb-Turbine Efficiency Using Numerical Flow Simulation

At the smallest scale, hydropower or pico-hydro can be produced by utilizing water flow at the piping system. This paper discusses about the performance of a water bulb-turbine in a water piping water system using the Computational Fluid Dynamic (CFD) method. This study aims to analyze the effect of flow rate and speed on the efficiency of water bulb-turbine using Solidworks Flow Simulation 2016. The propeller turbine design used in this study has 4 blades and a blade angle of 200, and the static bulb using with a ratio of 0.6 to the pipe diameter. The parameter in flow rate applied in this study is between 7 and 13 L/s and for speed parameter between 100 and 1700 rpm. The final result of this study indicates that the efficiency of the water bulb-turbine is a directly proportional increase of flow rate and the highest efficiency reaches at flow rate 13 L/s and 1300 rpm.

Оценка пропуска минимальных расходов воды сооружениями дюкерного типа мелиоративных систем

Issues related to the design and hydraulic calculation of the transit part of a closed tubular water supply structure of the siphon type is considered. The operating conditions of the siphon with rectangular pipes in the transition mode are evaluated, in which the entrance section of the pipes of the culvert structure experiences increased hydrodynamic loads, often leading to certain destructions. The siphon design was modeled with two breaks along the length with a smooth inlet head and without a head. During the experiments, the absence of infl uence of the inlet head of the tubular HTS on the length of the free-flow section was noted. It has been established that the conditions of formation and features of the hydraulic operation of the siphon in the transient mode are largely determined by its design features. With the flooding of the inlet head, the flow of air into the pipe is hindered and a transition mode of the second type is formed with a slight fluctuation of the water level in the upper pool. The dependence of the location of the point of separation of the flow with a decrease in the passing water flow rate on its value is revealed, which made it possible to obtain a graph of the dependence of the relative length of the non-pressure end section on the square root of the Froude number. A comparison was made with the results of studies by other authors, which showed an increase in the relative length in tubular HTS of the siphon type in sections with reverse slopes at the same Froude numbers. Recommendations are given on the methodology for carrying out hydraulic calculation of tubular structures of the siphon type with minimal flow rates.

Glomerular filtration and diuresis are related to the state of lipids peroxidation in female rats exposed to water-salt loads accompanied by chronic stress

Background. It is known about the existence of close functional link between adequate working kidney nephrons and bone metabolism. Focused monitoring of renal function is able to provide substantial assistance in the organization of preventive measures against latently emerging osteoporosis. Activation of lipoperoxidation is known to inhibit glomerular filtration, whereas antioxidants prevent this. We set ourselves the goal of clarifying correlations between glomerular filtration, as well as tubular water reabsorption and daily diuresis, on the one hand, and lipoperoxidation parameters, on the other hand. Materials and Methods. Experiment was performed on 50 healthy female Wistar rats 240-290 g, both intact and exposed to water-salt loads. By the size of the diuresis and the level of creatinine in plasma and urine, glomerular filtration and tubular reabsorption were calculated. The plasma levels of diene conjugates and malondyaldehide as well as catalase of plasma and superoxide dismutase of erythrocytes were determined. The levels of the first three parameters determined in urine too. Results. In conditions of water-salt loads accompanied by chronic stress, glomerular filtration is downregulated by malondialdehyde and superoxide dismutase; diuresis is also downregulated by malondialdehyde, but upregulated by catalase. Lipoperoxidation parameters determine kidney function by 52,8%. Conclusion. The obtained data indicate the role of lipoperoxidation as a accompaniment of chronic stress in the regulation of kidney functions.

Growth Hormone and IGF1 Actions in Kidney Development and Function.

Growth hormone (GH) exerts multiple effects on different organs including the kidneys, either directly or via its main mediator, insulin-like-growth factor-1 (IGF-1). The GH/IGF1 system plays a key role in normal kidney development, glomerular hemodynamic regulation, as well as tubular water, sodium, phosphate, and calcium handling. Transgenic animal models demonstrated that GH excess (and not IGF1) may lead to hyperfiltration, albuminuria, and glomerulosclerosis. GH and IGF-1 play a significant role in the early development of diabetic nephropathy, as well as in compensatory kidney hypertrophy after unilateral nephrectomy. Chronic kidney disease (CKD) and its complications in children are associated with alterations in the GH/IGF1 axis, including growth retardation, related to a GH-resistant state, attributed to impaired kidney postreceptor GH-signaling and chronic inflammation. This may explain the safety of prolonged rhGH-treatment of short stature in CKD.

Water flow regulator for irrigation canals

A distinctive feature of the irrigated systems of the Russian Federation is a large area of irrigated areas and a significant length of irrigation canals. With a large area of the irrigated massif on small canals, the use of electricity to regulate the throughput of network hydraulic structures is economically ineffective. Preference is given to means of hydraulic automation of water supply. Regulation of the throughput of a hydraulic structure is based on the laws of fluid flow within it. On irrigation canals in Russia, as in world practice, water-operated gates are widely used. One of the disadvantages of such gates is moving metal parts and sensors, which reduce the operational reliability of structures. A new regulator of throughput is proposed, the action of which is based on the injection effect. Compression of the flow by physical elements was replaced by the circulation of surplus water supply between the outlet section of the water supply structure and the downstream. The regulator is built into the pressure drop between the high and low order channels. Regulating the throughput of the tubular water outlet automatically begins after shutting down one or more sprinklers that take water from the lower order canal. After turning the sprinklers into operation, the regulator automatically restores the original throughput. Using the theory of jet pumps, a new method has been developed for the theoretical determination of the main hydraulic characteristics of the regulator. These include the size of the nozzle and the velocities of the injection and injection streams. The derivation of theoretical dependencies was based on the classical equations of fluid mechanics; the flow within the structure was considered quasi-one-dimensional. The obtained calculated dependencies were verified using numerical and physical modeling. The data of the physical and numerical experiment were in good agreement with the theoretical dependences. Further optimization of the controller can be performed by changing its geometric parameters.

Purinergic signaling is enhanced in the absence of UT-A1 and UT-A3.

ATP is an important paracrine regulator of renal tubular water and urea transport. The activity of P2Y2, the predominant P2Y receptor of the medullary collecting duct, is mediated by ATP, and modulates urinary concentration. To investigate the role of purinergic signaling in the absence of urea transport in the collecting duct, we studied wild‐type (WT) and UT‐A1/A3 null (UT‐A1/A3 KO) mice in metabolic cages to monitor urine output, and collected tissue samples for analysis. We confirmed that UT‐A1/A3 KO mice are polyuric, and concurrently observed lower levels of urinary cAMP as compared to WT, despite elevated serum vasopressin (AVP) levels. Because P2Y2 inhibits AVP‐stimulated transport by dampening cAMP synthesis, we suspected that, similar to other models of AVP‐resistant polyuria, purinergic signaling is increased in UT‐A1/A3 KO mice. In fact, we observed that both urinary ATP and purinergic‐mediated prostanoid (PGE2) levels were elevated. Collectively, our data suggest that the reduction of medullary osmolality due to the lack of UT‐A1 and UT‐A3 induces an AVP‐resistant polyuria that is possibly exacerbated by, or at least correlated with, enhanced purinergic signaling.

P0020THE NEPHRO-PROTECTIVE ROUTE OF CGMP DOES NOT COMPENSATE NPRHOGENIC DIABETES INSIPIDUS, BOTH CONDITIONS MEDIATED BY RENAL INTEGRIN LINKED KINASE (ILK)

Abstract Background and Aims Renal ILK transgenic deletion on mice (cKD-ILK) address basal polyuria compatible with nephrogenic diabetes insipidus (NDI), due to disrupted tubular water channel aquaporin 2 (AQP2) AQP2 expression and vesicular trafficking to the apical membrane [Cano-Peñalver JL et al. FASEB J. 2014; Mamuya FA et al. Am J Physiol Renal Physiol. 2016]. An early symptom of chronic renal diseases (CKD) is NDI. ILK depletion also have a nephron-protective effect in renal damage in mice due to the increase in cGMP [Cano-Peñalver JL et al. Mol Med. 2016; de Frutos S et al. Biochim Biophys Acta Mol Basis Dis. 2019], the latter an alternative anti-NDI mediator. Here we demonstrate that ILK-mediated regulation of AQP2, under basal or CKD contexts, does not depend on cGMP. Method cKD-ILK and controls (WT) were treated orally with a NO donor, as precursor of cGMP formation (IDN, 300mg / Kg / day) for 24 hours. Urine volume was determined as a measure of tubular functionality. Fresh kidneys from non-treated mice were cultured ex vivo with precursors of cGMP (NO donor SNP, 1 µM or cGMP analogue 8Br-cGMP, 0.2 mM) for 30 minutes. AQP2 in the apical membrane of the tubules was quantified by immunohistochemistry. More cKD-ILK and WT were subjected for 6 weeks to a diet supplemented with 0.2% adenine (A) as CKD inducer or baseline standard diet. Urine volume and total ranal AQP2 levels were determined. Results Compared to WT, cGMP axis activation in vivo did not compensate the basal NDI present in cKD-ILK and the activation ex vivo did not improve the apical presence of AQP2 in cKD-ILK. Both WT and cKD-ILK subjected to CKD showed exacerbated polyuria and decreased levels of renal AQP2, but no differences were observed between groups. Conclusion ILK regulates AQP2, both in a basal and pathological context (CKD) independent of cGMP which otherwise is nephron-protective. Our results probably explain the co-existence of cGMP increase together with AQP2 decrease observed in the cKD-ILK kidneys.

Prostaglandin E2 stimulates the epithelial sodium channel (ENaC) in cultured mouse cortical collecting duct cells in an autocrine manner.

Prostaglandin E2 (PGE2) is the most abundant prostanoid in the kidney, affecting a wide range of renal functions. Conflicting data have been reported regarding the effects of PGE2 on tubular water and ion transport. The amiloride-sensitive epithelial sodium channel (ENaC) is rate limiting for transepithelial sodium transport in the aldosterone-sensitive distal nephron. The aim of the present study was to explore a potential role of PGE2 in regulating ENaC in cortical collecting duct (CCD) cells. Short-circuit current (ISC) measurements were performed using the murine mCCDcl1 cell line known to express characteristic properties of CCD principal cells and to be responsive to physiological concentrations of aldosterone and vasopressin. PGE2 stimulated amiloride-sensitive ISC via basolateral prostaglandin E receptors type 4 (EP4) with an EC50 of ∼7.1 nM. The rapid stimulatory effect of PGE2 on ISC resembled that of vasopressin. A maximum response was reached within minutes, coinciding with an increased abundance of β-ENaC at the apical plasma membrane and elevated cytosolic cAMP levels. The effects of PGE2 and vasopressin were nonadditive, indicating similar signaling cascades. Exposing mCCDcl1 cells to aldosterone caused a much slower (∼2 h) increase of the amiloride-sensitive ISC. Interestingly, the rapid effect of PGE2 was preserved even after aldosterone stimulation. Furthermore, application of arachidonic acid also increased the amiloride-sensitive ISC involving basolateral EP4 receptors. Exposure to arachidonic acid resulted in elevated PGE2 in the basolateral medium in a cyclooxygenase 1 (COX-1)-dependent manner. These data suggest that in the cortical collecting duct, locally produced and secreted PGE2 can stimulate ENaC-mediated transepithelial sodium transport.

Renal denervation in 2019

In the 21st century, hypertension remains a major health threat to the adult population worldwide, despite the phenomenal progress in the development of antihypertensive pharmacotherapy. Currently, the rate of pharmacological control of hypertension barely exceeds 50%. Indeed, pharmacotherapy is fundamentally limited by pharmacological/pharmacokinetic tolerance (adaptation) to the drugs as well as by non-compliance of patients with treatment regimens due to depletion of their psychophysiological function of self-control. Renal denervation (RDN) is a new non-drug treatment of hypertension. Renal denervation consists of a mini-electrosurgery on the renal sympathetic system where a catheter ablation is used to create a permanent block of conduction through the renal nerves. This procedure, in accordance with the function of the renal adrenergic receptors, increases glomerular filtration, reduces tubular water reabsorption, and inhibits glomerular secretion of renin. After the over-disputed failure of the early version of RDN using the first-generation single-electrode catheter system in the SYMPLICITY HTN-3 study, therapy was virtually reinvented with a new three-dimensional multi-electrode design and an anatomically optimized procedure. The new device design ensures deployment of the electrodes in a pre-defined fully circumferential pattern. Moreover, this design provides a radial contact that presses the electrodes against the arterial wall thereby maximizing the efficiency of radiofrequency (RF) tissue heating. Another major improvement of RDN therapy is the anatomical optimization of the procedure by extending the treatment into the segmental branches of the renal artery where the renal nerves concentrate the most around renal vessels. This article presents an analysis of the current state-of-the-development and future perspectives of RDN therapy.

CHRONIC NITRIC OXIDE SYNTHASE INHIBITION INCREASES RENAL VASOPRESSIN EFFECTS IN NORMOTENSIVE RAT

Objective: Nitric oxide is an important modulator of vascular tone but also of the sodium and water balance. These phenomena appear to be of particular relevance in the control of blood pressure and the development of arterial hypertension. Design and method: We evaluated in 4 week-old Wistar Kyoto normotensive rats the effects of chronic inhibition of nitric oxide synthase through NG-nitro-L-arginine methyl ester (L-NAME, 7.5 mg / kg / day per 4 weeks) on water and sodium balance. Results: The dose of L-NAME administered orally for 4 weeks did not generate a significant increase in blood pressure (116 ± 10 vs 112 ± 8). The volume of diuresis was reduced, associated with an increase in urine osmolarity in the group treated with L-NAME. Natriuresis levels were not significantly different between L-NAME treated and untreated rats. Urinary aquaporin2/creatinine ratio was significantly elevated in L-NAME group of rat (p < 0.05). Plasma and urinary metabolites of nitric oxide (NOx) were reduced in L-NAME treated rats as compared to untreated. Conclusions: These results support that nitric oxide synthase inhibition, at subpressor doses, determine a positive water balance by increasing tubular effect of vasopressin that lead to higher tubular water channel (aquaporin2) expression, and subsequently to the shedding in the urine.

Inhibition of inflammation using diacerein markedly improved renal function in endotoxemic acute kidney injured mice

BackgroundInflammation is an important pathogenic component of endotoxemia-induced acute kidney injury (AKI), finally resulting in renal failure. Diacerein is an interleukin-1β (IL-1β) inhibitor used for osteoarthritis treatment by exerting anti-inflammatory effects. This study aims to investigate the effects of diacerein on endotoxemia-induced AKI.MethodsMale C57BL/6 mice were intraperitoneally injected with lipopolysaccharide (LPS, 10 mg/kg) for 24 h prior to diacerein treatment (15 mg/kg/day) for another 48 h. Mice were examined by histological, molecular and biochemical approaches.ResultsLPS administration showed a time-dependent increase of IL-1β expression and secretion in kidney tissues. Diacerein treatment normalized urine volume and osmolarity, reduced blood urea nitrogen (BUN), fractional excretion of sodium (FENa), serum creatinine and osmolarity, and protected renal function in an endotoxemic AKI mice model. In the histopathologic study, diacerein also improved renal tubular damage such as necrosis of the tubular segment. Moreover, diacerein inhibited LPS-induced increase of inflammatory cytokines, such as IL-1β, tumor necrosis factor-α, monocyte chemoattractant protein-1 and nitric oxide synthase 2. In addition, LPS administration markedly decreased aquaporin 1 (AQP1), AQP2, AQP3, Na,K-ATPase α1, apical type 3 Na/H exchanger and Na-K-2Cl cotransporter expression in the kidney, which was reversed by diacerein treatment. We also found that diacerein or IL-1β inhibition prevented the secretion of inflammatory cytokines and the decrease of AQP and sodium transporter expression induced by LPS in HK-2 cells.ConclusionOur study demonstrates for the first time that diacerein improves renal function efficiently in endotoxemic AKI mice by suppressing inflammation and altering tubular water and sodium handing. These results suggest that diacerein may be a novel therapeutic agent for the treatment of endotoxemic AKI.

Study of Opto-Mechanical Properties of Tubular Water Quenched Polyethylene Films

Tubular Water Quench (TWQ) is commonly used process to make Polypropylene based films (TQPP). This process has been tried for the first time to make Polyethylene films (TQPE) from HDPE-LLDPE blend. Polyethylene inculcates the inherent materialistic property of softness and better feel to the film. The key requirement for TWQ films are Openability and transparency. This paper focuses on novel developmental work done, using Polyethylene blend for making TQPE film, comparing it’s optical and mechanical properties with TQPP films.

Clopidogrel Partially Counteracts Adenosine-5′-Diphosphate Effects on Blood Pressure and Renal Hemodynamics and Excretion in Rats

BackgroundAdenosine-5′-diphosphate (ADP) can influence intrarenal vascular tone and tubular transport, partly through activation of purine P2Y12 receptors (P2Y12-R), but their actual in vivo role in regulation of renal circulation and excretion remains unclear. MethodsThe effects of intravenous ADP infusions of 2-8mg/kg/hour were examined in anesthetized Wistar rats that were untreated or chronically pretreated with clopidogrel, 20mg/kg/24hours, a selective P2Y12-R antagonist. Renal blood flow (transonic probe) and perfusion of the superficial cortex and medulla (laser-Doppler fluxes) were measured, together with urine osmolality (Uosm), diuresis (V), total solute (UosmV), sodium (UNaV) and potassium (UKV) excretion. ResultsADP induced a gradual, dose-dependent 15% decrease of mean arterial pressure, a sustained increase of renal blood flow and a 25% decrease in renal vascular resistance. Clopidogrel pretreatment attenuated the mean arterial pressure decrease, and did not significantly alter renal blood flow or renal vascular resistance. Renal medullary perfusion was not affected by ADP whereas Uosm decreased from 1,080 ± 125 to 685 ± 75 mosmol/kg H20. There were also substantial significant decreases in UosmV, UNaV and UKV; all these changes were attenuated or abolished by clopidogrel pretreatment. Two-weeks’ clopidogrel treatment decreased V while UosmUosmV and UNaV increased, most distinctly after 7 days. Acute clopidogrel infusion modestly decreased mean arterial pressure and significantly increased outer- and decreased inner-medullary perfusion. ConclusionsOur functional studies show that ADP can cause systemic and renal vasodilation and a decrease in mean arterial pressure, an action at least partly mediated by P2Y12 receptors. We confirmed that these receptors exert tonic action to reduce tubular water reabsorption and urine concentration.

Enzymatic sources and physio-pathological functions of soluble (pro)renin receptor.

(Pro)renin receptor (PRR) belongs to type I transmembrane receptor family and binds both prorenin and renin, representing a potential regulator of the activity of the renin-angiotensin system. Soluble form of PRR (sPRR) is generated by intracellular protease-mediated cleavage of full-length PRR. The purpose of this review is to highlight recent advances in understanding the mechanisms of action and production of sPRR. It has recently been demonstrated that site-1-protease (S1P) plays a dominant role in the generation of sPRR. New evidence is also emerging to support a biological function of sPRR in the physiological regulation of fluid homeostasis as well as pathogenesis of chronic kidney disease. sPRR is a 28 kDa product of PRR cleavage via S1P-mediated protease activity. Not only does sPRR regulate renal tubular water transport, but it also mediates pathogenic responses to renal cellular injury. sPRR is likely involved in a wide range of physio-pathological processes.