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Acetaminophen (APAP) is a widely prescribed analgesic and antipyretic drug. In the present work, we studied the effects of glutamine (Gln) in an in vivo model of APAP-induced nephrotoxicity in male Wistar rats. Renal function, histological characteristics, and Na+,K+-ATPase cortical abundance and distribution were analyzed. The appearance of HSP70 and actin in urine was also evaluated. Myeloperoxidase (MPO) activity in cortical tissue was measured as an index of the inflammatory response. Gln administration 30 min before APAP protected from the renal functional and histological damage promoted by APAP. Rats that received the dual treatment Gln and APAP (Gln/APAP) showed the same level of Na+,K+-ATPase cortical induction as APAP-treated animals, but the enzyme maintained its normal basolateral localization. HSP70 abundance was increased up to the same level in the Gln, APAP, and Gln/APAP groups. Urinary HSP70 and actin were detected only in the APAP-treated animals, reinforcing the protection of renal tubular integrity afforded by the Gln pretreatment. Gln pretreatment also protected from the increment in MPO activity promoted by APAP. Our results support the idea that Gln pretreatment could be a therapeutic option to prevent APAP-induced renal injury. Fil: Brovedan, Marco Alcides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina Fil: Molinas, Sara Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina Fil: Pisani, Gerardo Daniel. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Ciencias Fisiológicas. Área Morfología; Argentina Fil: Monasterolo, Liliana Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina Fil: Trumper, Laura. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina. Universidad Nacional de Rosario. Centro de Investigaciones de la Universidad Nacional de Rosario; Argentina

During ischemic acute kidney injury (AKI), loss of cytoskeletal integrity and disruption of intercellular junctions are rapid events in response to ATP depletion. Angiotensin II type 2 receptor (AT2R) is overexpressed in injury situations and its stimulation by angiotensin II (AngII) is related to beneficial renal effects. Its role on ischemic AKI has not been deeply studied. The aim of the present study was to investigate whether pretreatment with the AT2R agonist, C21, prevents ischemic renal epithelial cell injury. Studies in a model of 40 min of renal ischemia followed by 24 h of reperfusion (IR) in rats demonstrated that C21 pretreatment attenuated renal dysfunction and induced better preservation of tubular architecture. In addition, we studied the expression of Rho GTPases, RhoA and Cdc42, since they are key proteins in the regulation of the actin cytoskeleton and the stability of epithelial intercellular junctions. IR downregulated RhoA and Cdc42 abundance in rat kidneys. C21 pretreatment prevented RhoA reduction and increased Cdc42 abundance compared to controls. We also used an in vitro model of ATP depletion in MDCK cells grown on filter support. Using immunofluorescence we observed that in MDCK cells, C21 pretreatment prevented the ATP depletion-induced reduction of actin in brush border microvilli and in stress fibers. Moreover, C21 prevented membrane E-cadherin reduction, and RhoA and Cdc42 downregulation. The present study describes for the first time a renoprotective effect of the AT2R agonist, C21, against AKI, and provides evidence supporting that stimulation of AT2R triggers cytoprotective mechanisms against an ischemic event. Fil: Fussi, María Fernanda. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina Fil: Hidalgo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina Fil: Buono, Gabriel Marcelo. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina Fil: Marquez, Susana Beatriz. Universidad Nacional de Rosario. Facultad de Ciencias Médicas; Argentina Fil: Pariani, Alejandro Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina Fil: Molinas, Jorge Luis. Universidad Nacional de Rosario. Facultad de Cs.médicas. Escuela de Cs.médicas. Cátedra de Fisiología; Argentina Fil: Larocca, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina Fil: Monasterolo, Liliana Alicia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina Fil: Molinas, Sara Maria. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Area Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina

Accumulating evidence indicates the association between changes in circulating sex steroid hormone levels and the development of diabetic nephropathy. However, the renal synthesis of steroid hormones during diabetes is essentially unknown. Male Wistar rats were injected with streptozotocin (STZ) or vehicle. After one week, no changes in functional or structural parameters related to kidney damage were observed in STZ group; however, a higher renal expression of proinflammatory cytokines and HSP70 was found. Expression of Steroidogenic Acute Regulatory protein (StAR) and P450scc (CYP11A1) was decreased in STZ kidneys. Incubation of isolated mitochondria with 22R-hydroxycholesterol revealed a marked inhibition in CYP11A1 function at the medullary level in STZ group. The inhibition of these first steps of renal steroidogenesis in early STZ-induced diabetes led to a decreased local synthesis of pregnenolone and progesterone. These findings stimulate investigation of the probable role of nephrosteroids in kidney damage associated with diabetes. Fil: Pagotto, Melina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina Fil: Roldán, María Lorena. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina Fil: Molinas, Sara Maria. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Área Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina Fil: Raices, Trinidad. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Pisani, Gerardo Bruno. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Ciencias Fisiológicas. Área Morfología; Argentina Fil: Pignataro, Omar Pedro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Monasterolo, Liliana Alicia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmaceuticas. Departamento de Ciencias Fisiológicas. Área Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina

Acetaminophen (APAP) is an analgesic-antipyretic drug widely used in children. In the present study, we used an in vivo model of APAP-induced nephrotoxicity in male Wistar rats. We analyzed whether toxic doses of APAP could induce heat shock protein 70 (HSP70) in the kidney and whether HSP70 could be detected in urine. Renal function and histological evaluation of the kidneys were performed at different times after APAP administration (1,000 mg/kg body weight i.p.). Cellular injury was assessed by Triton X-100 solubilization of Na(+)/K(+) ATPase. Renal and hepatic glutathione levels were also measured. Urinary N-acetyl-beta-D glucosaminidase (NAG) excretion increased 4 h after intoxication. At this time, urea and creatinine were at control levels and a slight degree of histological alteration was detected. Kidney microscopic evaluation, Na(+)/K(+) ATPase solubility, creatinine, and urea levels and NAG excretion did not differ from those of controls 48 h after APAP administration. HSP70 was detected in urine obtained from 4 to 24 h after APAP administration. HSP70 abundance in renal cortex was increased at early time points and 48 h after APAP administration. Urinary HSP70 excretion would be a marker of its renal induction combined with the loss of tubule integrity. NAG would be a suitable early biomarker of APAP-induced nephrotoxicity.

In previous works we reported that the administration of a toxic dose of acetaminophen (APAP) induces acute renal failure (ARF) and promotes changes on Na(+), K(+)ATPase distribution in renal proximal plasma membranes. In the present work, we analyzed if APAP could promote the dissociation of Na(+), K(+)ATPase from its membrane anchorage. The participation of calpain activation was also evaluated. We analyzed the Triton X-100 extractability of Na(+), K(+)ATPase in freshly isolated cortical cell suspensions incubated with different APAP concentrations (0.1, 1, 10 and 100 mM). Both alpha(1) and beta(1) subunits were studied by Western blot. APAP promoted the increment of both subunits abundance in the Triton-soluble fraction. Calpain activation was detected in the membrane fractions of cells incubated with APAP. Incubation with APAP 0.1, 1 and 10 mM did not promote an increment in LDH release compared with controls, while APAP 100 mM promoted an increased LDH release. Our results show that incubation of proximal cells with sublethal and lethal APAP concentrations promotes the detachment of Na(+), K(+)ATPase from its membrane anchoring. Inhibition of calpain activation by SJA 7029 protected against APAP-induced membrane damage but not against APAP-induced increase of the Triton X-100 extractability of Na(+), K(+)ATPase.

The purpose of this study was to assess the effects of the cyclooxygenase inhibitor, indomethacin, and some vasoactive agents on the renal functional parameters during the early liver injury induced by four days bile duct ligation (BDL). Wistar rats with four days-BDL and control-sham operated were used. Renal function was measured in anesthetized rat treated with a single dose of indomethacin (control, 0.3, 1.0, 3.0 mg/kg b.w.; i.v.) one hour before clearance studies. Sulindac effects were also evaluated (5 mg/kg b.w., i.p). Isolated rat kidney preparations from control and BDL donor rats were used to study renal vascular response to noradrenaline, carbachol or sodium nitroprusside. The bile duct ligation promoted a diminished renal cortical plasma flow (RCPF) on the fourth day post surgery accompanied with a diminution in the glomerular filtration rate (GFR), increased filtration fraction and increased fractional excretion of water and sodium. Indomethacin 0.3 mg/kg induced an increase in GFR and RCPF, maintaining the high filtration fraction in BDL rats. The other doses did not alter these parameters as compared with bile duct ligated rats without treatment, but indomethacin 3 mg/kg caused a significant increase in filtration fraction. Indomethacin induced dose-dependent diminution in natriuresis in sham and BDL groups. Sulindac did not modify hemodynamic parameters, but induced antinatriuresis and antidiuresis in both experimental groups. Maximal vascular responses to noradrenaline measured in isolated rat kidneys were statistically diminished in BDL-rats as compared with controls (C, n=7; 35.0+/-2.3 mmHg ml(-1) min; BDL-rats, n=5; 23.8+/-0.7 mmHg ml(-1) min; p0.02), without changes in EC15. Maximal relaxation induced by sodium nitroprusside in the phenylephrine (PHE)-pre-constricted renal vasculature in control preparations did not differ from that observed in BDL group (C: n=6; 49.5+/-2.3%). Values of EC50 were 1.26+/-0.07 microM (n=6) in control preparations and 0.34+/-0.03 microM (n=4) in kidneys from BDL-rats (p0.001). Carbachol induced a biphasic relaxation of PHE-pre-constricted renal vasculature. No differences in maximal responses were found. EC50 value of the second phase in BDL group was significantly decreased compared to control preparations (C: n=6, 0.47+/-0.05 microM; BDL: n=6, 0.22+/-0.03 microM p0.001). The present results show that the altered renal function after a short time post bile duct ligation is determined, at least in part, by increased release of arachidonic derivatives in vascular bed and tubular cells. At this stage of liver injury, the alteration in the renal vascular response to different vasoactive agents is remarkable.

The effects of the in vivo administration of baclofen on renal tubular transport and aquaporin-2 (AQP2) expression were evaluated. In conscious animals kept in metabolic cages, baclofen (0.01-1 mg/kg, s.c.) induced a dose-dependent increment in the urine flow rate (UFR) and in sodium and potassium excretion, associated with an increased osmolal clearance (Closm), a diminished urine to plasma osmolality ratio (Uosm/Posm) and a decrease in AQP2 expression. The above mentioned baclofen effects on functional parameters were corroborated by using conventional renal clearance techniques. Additionally, this model allowed the detection of a diminution in glucose reabsorption. Some experiments were performed with water-deprived or desmopressin-treated rats kept in metabolic cages. Either water deprivation or desmopressin treatment decreased the UFR and increased the Uosm/Posm. Baclofen did not change the Uosm/Posm or AQP2 expression in desmopressin-treated rats; but it increased the UFR and diminished the Uosm/Posm and AQP2 expression in water-deprived animals. These results indicate that in vivo administration of baclofen promotes alterations in proximal tubular transport, since glucose reabsorption was decreased. The distal tubular function was also affected. The increased Closm indicates an alteration in solute reabsorption at the ascending limb of the Henle's loop. The decreased Uosm/Posm and AQP2 expression in controls and in water-deprived, but not in desmopressin-treated rats, lead us to speculate that some effect of baclofen on endogenous vasopressin availability could be responsible for the impaired urine concentrating ability, more than any disturbance in the responsiveness of the renal cells to the hormone. Fil: Donato, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Pisani, Gerardo Bruno. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Trumper, Laura. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Monasterolo, Liliana Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The effects of diazepam were studied in the isolated rat kidney under conditions of constant flow. Kidneys were perfused with modified Ringer-Krebs solution. Diazepam produced a raised fractional excretion of water and sodium without hemodynamic changes, suggesting a direct effect on tubular transport mechanisms. Diazepam decreased renal perfusion pressure in a concentration-dependent fashion when kidneys were pretreated with either noradrenaline or potassium chloride. Similar responses were observed when 7-chloro-5-[4-chloro-phenyl]-1, 3-dihydro-1-methyl-2H-1,4-benzodiazepin-2-one (Ro 5-4864) or clonazepam was used. These data provide evidence for a relaxant effect of benzodiazepines on preconstricted renal vasculature.

The effects of different acetaminophen (APAP) concentrations (1,5 or 10 mM) on renal function were investigated in the isolated perfused rat kidney (IPK). APAP was added to the perfusion media as a single dose after a equilibration time and control periods. Changes in fractional excretion of sodium (FENa), water \(\left( {FE_{H_2 O} } \right)\), glucose (FEglu) and in glomerular filtration rate (GFR) were measured. The lower concentration used only modified the \(FE_{H_2 O} \). APAP 10 mM induced an increment in \(FE_{H_2 O} \) (72% higher than control preparation), FENa (79% higher than control preparation) and an elevation in glucose excretion (55% higher than control preparation), associated with a decrease in GFR (23% lower than control preparation). The influence of PGE2 on the effects of APAP was also investigated. PGE2 prevented the APAP-induced decrease in GFR and in glucose reabsorption, but did not change the pattern of sodium and water handling. The effects of another vasodilator, verapamil, on APAP-induced renal effects were also tested. Verapamil prevented the glomerular but not the tubular effects of APAP. Urinary APAP excretion data showed a similar availability of APAP to the tubular cells in all the groups. Our data suggest that APAP exerts a direct action in the IPK, affecting hemodynamic and tubular functions, and that the latter are not a consequence of hemodynamic alterations.

Cumulative evidence demonstrated effective downstream metabolism of pregnenolone in renal tissue. The aim of this study was to evaluate the expression and functional activity of cytochrome P450 side chain cleavage enzyme (CYP11A1), which converts cholesterol into pregnenolone, in adult rat kidney. Immunohistochemical labeling for CYP11A1 was observed in renal cortex and medulla, on structures identified as distal convoluted tubule and thick ascending limb of Henle's loop, respectively. Immunoblotting analysis corroborated the renal expression of the protein in inner mitochondrial membrane fractions. The incubation of isolated mitochondria with the membrane-permeant cholesterol analogue 22R-hydroxycholesterol resulted in efficient formation of pregnenolone, the immediate precursor for the synthesis of all the steroid hormones. The low progesterone production rate observed in these experiments suggested a poor activity of 3β-hydroxysteroid dehydrogenase enzyme in renal mitochondria. The steroidogenic acute regulatory protein (StAR), involved in the mitochondrial import of cholesterol, was detected in renal tissue at both mRNA and protein level. Immunostaining for StAR showed similar distribution to that observed for CYP11A1. The expression of StAR and CYP11A1 was found to be higher in medulla than in cortex. This enhanced expression of steroidogenesis-related proteins correlated with a greater pregnenolone synthesis rate and higher steroid hormones tissular content measured in medulla. In conclusion, we have established the expression and localization of StAR and CYP11A1 protein, the ability of synthesizing pregnenolone and a region-specific content of sex hormones in the adult rat kidney. These data clearly show that the kidney is a steroid hormones synthesizing organ. It is proposed that the existence in the kidney of complete steroidogenic machinery would respond to a physiological significance. © 2010 Elsevier Ireland Ltd. Fil: Pagotto, Melina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina Fil: Roldán, María Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Pagotto, Romina María del Luján. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Lugano, Maria C.. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Pisani, Gerardo. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Rogic, Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Molinas, Sara Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Fisiología Experimental. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Fisiología Experimental; Argentina Fil: Trumper, Laura. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina Fil: Pignataro, Omar Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Monasterolo, Liliana Alicia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Renal functions during the early stage of hepatic damage before ascites formation were studied in adult female rats. Tubular and hemodynamic parameters were analyzed for 12 days after common bile duct ligation. The fractional excretion of water, sodium, and potassium increased from control values at every day studied. Glomerular filtration rate and renal plasma flow were found to be diminished on the fourth day. Renal plasma flow remained decreased while glomerular filtration rate was recovered on the sixth day after common bile duct ligation. Filtration fraction in both experimental groups (4 and 6 days) was higher than in control animals. These observations suggested a preferential efferent arteriole vasoconstriction that could be responsible for a blood flow redistribution to the medulla. This fact might cause the sodium diuresis with diminished urine-to-plasma osmolalities ratio. The onset of cortical vasoconstriction was confirmed by dopamine infusion to bile duct-ligated rats 4 days postsurgery. Hemodynamic and tubular parameters recovered to control values during dopamine administration. All the data point out diuresis and natriuresis as the earliest renal abnormalities in bile duct-ligated rats. This phenomenon could be associated not only to the cortical vasoconstriction proposed but also to another systemic modification associated to liver damage.

Diabetic nephropathy, one of the major microvascular complications of diabetes, is a leading cause of end-stage renal disease. This pathological entity is morphologically characterized by glomerular hypertrophy and thickening of tubular basal membranes, in association with progressive mesangial expansion. As the disease progresses, clinical manifestations include albuminuria, hypertension and declining glomerular filtration rate. Experimental and clinical studies have demonstrated the significant role of various inflammatory molecules in the setting of diabetic nephropathy, including acute phase reactants, inflammatory cytokines, adhesion molecules and chemokines (for review see Navarro-Gonzalez & Mora-Fernandez, 2008). Current treatment approaches include renin–angiotensin–aldosterone system inhibition, dietary sodium restriction and diuretic therapy. Nevertheless, new strategies are needed to slow down progression of diabetic nephropathy. In this issue of The Journal of Physiology, Chen and colleagues (2014) examined a possible mechanism involved in the beneficial effects of apelin-13 on experimental diabetic nephropathy. The adipokine apelin is a peptide known as the endogenous ligand of the G-protein-coupled receptor APJ. Apelin-13, the most active member of the apelin group, has emerged as a beneficial peptide with anti-obesity and antidiabetic properties, and thus, as a promising therapeutic target in metabolic disorders (for review see Castan-Laurell et al. 2011). Recently, Day et al. (2013) showed, for the first time, that apelin-13 exerts renoprotective effects in diabetic FVB/Ove26 mice. These authors observed that the whole-kidney and glomerular hypertrophy, as well as renal inflammation, was inhibited after treatment with apelin-13. These effects correlated with upregulation of the antioxidant catalase (Day et al. 2013). Chen et al. (2014) have added an important contribution by investigating the role of histone acetylation in apelin-induced effects on the diabetic kidney. Experiments carried out by these investigators demonstrated that apelin-13 inhibits histone hyperacetylation induced by either diabetes in the Akita mouse or high glucose concentration in cultured mesangial cells. This effect is mediated by selective upregulation of the expression of histone deacetylase HDAC1 (Chen et al. 2014). It is known that histone acetylation levels are regulated through the opposing activities of histone acetyltransferases and deacetylases, and that histone acetylation–deacetylation equilibrium plays a critical role in the control of gene expression. The participation of histone acetylation in the pathophysiology of diabetic nephropathy is still not well understood. As Chen et al. (2014) explain in their article (see their Discussion), previous studies demonstrated that histone hyperacetylation induces overexpression of inflammation-associated genes; and on the contrary, evidence has been accumulating that HDAC inhibitors exert renoprotective effects on the diabetic kidney. These controversies remain to be resolved. Probably, the identification of the individual transacetylase/deacetylase enzyme isoform involved in each case could contribute to elucidation of this issue. In the studies performed by Chen et al. (2014), the levels of two HDACs (HDAC1 and HDAC2) and two histone acetyltransferases (PCAF and GCN5) were determined. The expression level of only HDAC1 was affected by apelin-13 treatment in Akita mouse kidneys. In parallel with the diminution in histone acetylation levels, apelin-13 significantly reduced the diabetes-induced increase in renal monocyte chemotactic protein 1, intercellular adhesion molecule 1, inducible nitric oxide synthase and p65 [the active form of the transcriptional subunit of nuclear factor-κB (NF-κB)] phosphorylation levels of Akita mice (Chen et al. 2014). Interestingly, Ashburner et al. (2001) demonstrated that HDAC1 expression represses tumour necrosis factor-induced NF-κB-dependent gene expression. Consistent with this, the authors showed a direct association of HDAC1 with the Rel homology domain of p65. In diabetic nephropathy, an increase in the NF-κB p65 subunit and NF-κB–DNA binding depends on Toll-like receptor protein 2 (TLR2) upregulation (Mudaliar et al. 2013). In this connection, trichostatin A, a histone deacetylase inhibitor, upregulates the expression of both TLR2 mRNA and protein in the human THP-1 cell line (Li et al. 2013). Taking this information into account, it could be interesting to investigate whether the apelin-induced anti-inflammatory effects in diabetic nephropathy are mediated by direct association of the increased HDAC with p65 and/or TLR2 downregulation. In summary, the recently described effects of apelin on whole-body metabolism (for review see Castan-Laurell et al. 2011) and, especially, on the diabetic kidney (Day et al. 2013; Chen et al. 2014) lead to the proposal that apelin may be a novel therapeutic tool for treatment of diabetic nephropathy. The investigation by Chen et al. (2014) showed that apelin-13 alters the histone acetylation–deacetylation balance, exposing a wide spectrum of potential targets for the beneficial effects of this adipokine on diabetes-induced renal injury. Further investigations focused on elucidation of these mechanisms could contribute to evaluation of the risk–benefit ratio of apelin-13 treatment.

Background/Aims: Contributions to the understanding of acute renal failure (ARF) pathogenesis have not been translated into an effective clinical therapy. We studied the effects of pretreatment with the angiotensin II type 1 (AT1) receptor blocker, losartan, on renal function, tissue injury, inflammatory response and serum aldosterone levels in a model of ischemic ARF. Methods: Rats underwent unilateral renal ischemia followed by 24 h of reperfusion (IR), and were pretreated or not with 8 (IRL8) or 80 (IRL80) mg/kg/day of losartan for 3 days. Results: IR kidneys showed marked renal dysfunction, epithelial damage, capillary congestion, increased myeloperoxidase (MPO) activity and increased TNF-α, IL1-β and IL-6 mRNA levels. IRL80 kidneys showed protection against dysfunction and tissue injury, associated with normal MPO activity and cytokine mRNA levels. The lower dose was not able to achieve the same degree of functional renoprotection and could not prevent an increase of MPO or proinflammatory cytokine mRNA levels. The high losartan dose completely prevented an increase of serum aldosterone levels induced by IR. Conclusion: Renoprotection of the high losartan dose would be mainly mediated by its anti-inflammatory actions. Our results show a potential pathophysiological role of AT1 activation in promoting renal dysfunction, structural injury, inflammation and aldosterone elevation after IR injury.

The effects of the central-type benzodiazepine receptor antagonist flumazenil on renal vascular tone and its ability to reverse the benzodiazepine-induced vasodilation were investigated. The isolated and perfused rat kidney model was used. Flumazenil was unable to modify renal vascular resistance under basal conditions and in noradrenaline-pretreated kidneys. Relaxation induced by diazepam or clonazepam of noradrenaline-preconstricted renal vasculature was blunted by 10 microM flumazenil. These results suggest that central-type benzodiazepine receptors could be involved in benzodiazepine-induced renal vasodilation.

Glutamic acid decarboxylase (GAD) activity was measured in the oviduct of normal rats in diestrous and in rats ovariectomized (OVX) seven days before. OVX induced a significant decrease of GAD activity in the Fallopian tube. This effect was completely reversed by coadministration of estradiol benzoate + progesterone (E + P). Simultaneous injection of atropine, but not of α-methyl-para-tyrosine or labetalol, completely prevented the activation of GAD induced by ovarian sterois. Moreover. prostigmin significantly potentiated the action of E + P on GAD activity in the rat oviduct. These data clearly suggest the participation of acetylcholine in the mecanisms whereby ovarian steroids regulate GAD activity in the rat Fallopian tube.