ACE2 activator diminazene aceturate exerts renoprotective effects in gentamicin-induced acute renal injury in rats.

Acute Kidney Injury (AKI) comprises a rapidly developed renal failure and is associated with high mortality rates. The Renin-Angiotensin System (RAS) plays a pivotal role in AKI, as the over-active RAS axis exerts major deleterious effects in disease progression. In this sense, the conversion of Angiotensin II (Ang II) into Angiotensin-(1-7) (Ang-(1-7)) by the Angiotensin-converting enzyme 2 (ACE2) is of utmost importance to prevent worse clinical outcomes. Previous studies reported the beneficial effects of oral diminazene aceturate (DIZE) administration, an ACE2 activator, in renal diseases models. In the present study, we aimed to evaluate the therapeutic effects of DIZE administration in experimental AKI induced by gentamicin (GM) in rats. Our findings showed that treatment with DIZE improved renal function and tissue damage by increasing Ang-(1-7) and ACE2 activity, and reducing TNF-α. These results corroborate with a raising potential of ACE2 activation as a strategy for treating AKI.

Reduced endothelial nitric oxide synthase activation contributes to cardiovascular injury during chronic kidney disease progression.

Major cardiovascular events are a common complication in patients with chronic kidney disease (CKD). Endothelial dysfunction can contribute to the cardiovascular injury observed in CKD. Here, we used a rat model of acute kidney injury to CKD transition to investigate heart alterations in the pathway activating endothelial nitric oxide synthase (eNOS) and its impact on the cardiac injury observed during CKD progression. Fifty male Wistar rats were subjected to sham surgery (n = 25) or bilateral renal ischemia-reperfusion (IR-CKD) for 45 min (n = 25). Rats were studied on a monthly basis up to 5 mo (n = 5). In another set of sham and IR-CKD rats, l-arginine was administered starting on the third month after renal ischemia. CKD development and cardiac alterations were monitored in all groups. CKD was characterized by a progressive increase in proteinuria and renal dysfunction that was evident after the fifth month of followup. Heart hypertrophy was observed starting on the fourth month after ischemia-reperfusion. There was a significant increase in brain natriuretic peptide levels. In the heart, IR-CKD rats had increased eNOS phosphorylation at threonine 495 and reduced eNOS-heat shock protein-90α interactions. l-Arginine administration prevented the heart alterations observed during CKD and increased eNOS coupling/dimerization and activation. In summary, CKD progression is accompanied by cardiac hypertrophy, fibrosis, oxidative stress, and increased brain natriuretic peptide levels. These alterations were associated with limited eNOS activation in the heart, which may result in reduced nitric oxide bioavailability and contribute to cardiac injury during CKD.

Relationship between renal injury and the antagonistic roles of angiotensin-converting enzyme (ACE) and ACE2.

Angiotensin-converting enzyme 2 (ACE2), a newly discovered carboxypeptidase in the renin-angiotensin system (RAS), antagonizes ACE activity and plays an active role during tissue injury. Yet the mechanism of its action is not well known. Using a streptozotocin (STZ)-induced renal injury rat model, we investigated the relationship between renal injury and the antagonism between ACE and ACE2. We assayed the levels of urea nitrogen, urine glucose, creatinine, and protein, Ace2, Ace, angiotensin II type 1 receptor (At1) and Mas receptor mRNA, and renal and plasma angiotensin II (Ang II) in STZ-treated and untreated rats. We also used histology and immunohistochemistry to assess glomerular injury and ACE2 glomerular and cortical expression. The amounts of urea nitrogen, urine glucose, creatinine, and protein were significantly higher in STZ-treated rats than in control rats (P < 0.01). There were significant pathological changes in the kidney upon STZ-treatment. Ace2 and Ace mRNA levels were significantly higher in STZ-treated rats than in control rats (P < 0.05 and P = 0.05, respectively). There was no significant difference in the Mas receptor and At1 mRNA levels in the 2 groups, although At1 levels showed an increase upon STZ-treatment. The Ang II level in the renal cortical tissue and plasma of STZ-treated rats was higher than that of control rats (P < 0.05). The increase in Ace mRNA levels was higher than that of Ace2 mRNA levels, leading to an elevated Ace/Ace2 ratio. Together, these data suggest that the ACE-Ang II-AT1 axis is the dominant axis in severe kidney injury.

False positivity of gamma-glutamyl transpeptidase measurement in urine.

Although enzymuria tends to be associated to renal injury, there are no studies that have evaluated the presence of the enzyme gamma-glutamyl transpeptidase (GGT) spectrophotometry in the urine using a non-nephrotoxic agent (Nerium oleander) in order to evaluate the possibility of false positive results. The urinary GGT/urinary creatinine concentration ratio (uGGT/uCr) of 10 healthy dogs was calculated and posteriorly confronted with data from clinical evaluation, hematological and serum biochemical profiles, creatinine clearance (CrC), urinalysis, urine protein/creatinine ratio (UPC), electrocardiogram, systemic blood pressure (SBP) and light and electron microscopy. The results for kidney histology, SBP, UPC and CrC were not significantly different in any of the time-points analyzed. However, uGGT/uCr was significantly higher when measured 4 hours and 24 hours after administration of N. oleander. The measurement of the urinary GGT enzyme, as performed in many studies, yielded false positive results in dogs poisoned by a non-nephrotoxic agent.

Critical illness in energy metabolism genetic disorder: rhabdomyolysis, acute kidney injury, respiratory arrest / Enfermedad crítica por trastorno genético en el metabolismo de la energía: rabdomiolisis, lesión renal aguda, paro respiratorio

In very long-chain acylCoA dehydrogenase deficiency (VLCAD), the activity of this enzyme is either reduced or absent with the inability to use long-chain fatty acids as energy substrates. A 25-year old male with VLCAD was admitted to the Emergency Department of Policlinico Teaching Hospital (Modena, Italy) for generalized weakness and oliguria, after a period of physical and mental stress and inadequate compliance to a long-chain fatty acid free diet. Laboratory tests were compatible with acute kidney injury. Seventy-two hours after admission, the subject had an episode of chest pain with elevated markers of myocardial necrosis. The rapid deterioration of muscular strength and the subsequent worsening respiratory failure necessitated ventilator support within the local Medical Intensive Care Unit. There, the patient showed a prompt normalization of respiratory parameters and a steady improvement of renal function. An inadequate compliance to lifestyle and dietary restriction in VLCAD may trigger severe and potentially lethal crisis. The in-hospital management of these patients calls for early intensive care admission as their conditions may deteriorate without warning.

En el caso de deficiencia de acylCoA deshidrogenasa de cadena muy larga (VLCAD), o bien se reduce la actividad de esta enzima, o la misma se halla ausente con la consiguiente incapacidad para utilizar los ácidos grasos de cadena larga como sustratos de energía. Un hombre de 25 años fue ingresado con VLCAD fue admitido en el Departamento de emergencia del Hospital Policlínico Docente Hospital de Modena, en Italia, a causa de presentar debilidad generalizada y oliguria, después de un período de estrés físico y mental, y por no cumplir adecuadamente con una dieta libre de ácidos grasos de cadena larga. Las pruebas de laboratorio eran compatibles con una lesión renal aguda. Setenta y dos horas después de su ingreso, el sujeto tuvo un episodio de dolor en el pecho con marcadores elevados de necrosis miocárdica. El rápido deterioro de la fuerza muscular, y el posterior empeoramiento de la insuficiencia respiratoria requirieron el apoyo de un ventilador en la Unidad de Cuidados Médicos Intensivos. Una vez allí, el paciente mostró una pronta normalización de los parámetros respiratorios, y una constante mejoría de la función renal. Un inadecuado cumplimiento con las restricciones dietéticas y el estilo de vida en los casos de VLCAD, pueden desatar una crisis grave y potencialmente fatal. El tratamiento intrahospitalario de estos pacientes requiere un ingreso temprano en cuidados intensivos, ya que sus condiciones pueden deteriorarse sin previo aviso.

Involvement of catalase in the protective effect of binaphthyl diselenide against renal damage induced by glycerol.

In the present study, the protective effect of binapthyl diselenide [(NapSe)(2)] was investigated on glycerol-induced renal damage in rats. Adult male Wistar rats were treated with (NapSe)(2) (50 mg/kg, orally) or vehicle. After 24 h (NapSe)(2) treatment, the animals received an intramuscular injection of glycerol (8 ml/kg, dissolved in saline) or vehicle as a divided dose into the hind limbs. Twenty-four hours afterwards, rats were euthanized and the levels of urea and creatinine were measured in plasma. Non-protein thiol (NPSH) levels and catalase (CAT) activity were evaluated in renal homogenates. Histopathological evaluations were also performed in kidneys of rats. The rats exposed to glycerol presented swelling of the proximal and distal tubules with evidence of cell damage and death. Glycerol-exposed rats presented an increase in renal failure markers (plasmatic urea and creatinine levels) and a reduction in renal CAT activity. No change was observed in NPSH levels in kidneys of rats exposed to glycerol. (NapSe)(2) protected against the alterations caused by glycerol in rats. (NapSe)(2) increased per se NPSH levels (33%) in kidneys of rats. In conclusion, the results demonstrated that treatment with (NapSe)(2) protected against renal damage induced by glycerol in rats, probably due to its antioxidant effect.

Cisplatin-induced nephrotoxicity is associated with oxidative stress, redox state unbalance, impairment of energetic metabolism and apoptosis in rat kidney mitochondria.

The clinical use of cisplatin (cis-diamminedichloroplatinum II) is highly limited by its nephrotoxicity. The precise mechanisms involved in cisplatin-induced mitochondrial dysfunction in kidney have not been completely clarified. Therefore, we investigated in vivo the effects of cisplatin on mitochondrial bioenergetics, redox state, and oxidative stress as well as the occurrence of cell death by apoptosis in cisplatin-treated rat kidney. Adult male Wistar rats weighing 200-220 g were divided into two groups. The control group (n = 8) was treated only with an intraperitoneal (i.p.) injection of saline solution (1 ml per 100 g body weight), and the cisplatin group (n = 8) was given a single injection of cisplatin (10 mg/kg body weight, i.p.). Animals were sacrificed 72 h after the treatment. The cisplatin group presented acute renal failure characterized by increased plasmatic creatinine and urea levels. Mitochondrial dysfunction was evidenced by the decline in membrane electrochemical potential and the substantial decrease in mitochondrial calcium uptake. The mitochondrial antioxidant defense system was depleted, as shown by decreased GSH and NADPH levels, GSH/GSSG ratio, and increased GSSG level. Moreover, cisplatin induced oxidative damage to mitochondrial lipids, including cardiolipin, and oxidation of mitochondrial proteins, as demonstrated by the significant decrease of sulfhydryl protein concentrations and increased levels of carbonylated proteins. Additionally, aconitase activity, which is essential for mitochondrial function, was also found to be lower in the cisplatin group. Renal cell death via apoptosis was evidenced by the increased caspase-3 activity. Results show the central role of mitochondria and the intensification of apoptosis in cisplatin-induced acute renal failure, highlighting a number of steps that might be targeted to minimize cisplatin-induced nephrotoxicity.

The role of heme oxygenase 1 in rapamycin-induced renal dysfunction after ischemia and reperfusion injury.

Ischemia and reperfusion injury (IRI) is the main etiology of acute renal failure in native and transplanted kidneys. In the transplantation field, immunosuppressive drugs may play an additional role in acute graft dysfunction. Rapamycin may impair renal regeneration post IRI. Heme oxygenase 1 (HO-1) is a protective gene with anti-inflammatory and anti-apoptotic actions. We investigated whether HO-1 played a role in rapamycin-induced renal dysfunction in an established model of IRI. Rapamycin (3 mg/kg) was administered to mice before being subjected to 45 min of ischemia. Animals subjected to IRI presented with impaired renal function that peaked at 24 h (2.05+/-0.23 mg/dl), decreasing thereafter. Treatment with rapamycin caused even more renal dysfunctions (2.30+/-0.33 mg/dl), sustained up to 120 h after reperfusion (1.54+/-0.4 mg/dl), when compared to the control (0.63+/-0.09 mg/dl, P<0.05). Rapamycin delayed tubular regeneration that was normally higher in the control group at day 5 (68.53+/-2.30 vs 43.63+/-3.11%, P<0.05). HO-1 was markedly upregulated after IRI and its expression was even enhanced by rapamycin (1.32-fold). However, prior induction of HO-1 by cobalt protoporphyrin improved the renal dysfunction imposed by rapamycin, mostly at later time points. These results demonstrated that rapamycin used in ischemic-injured organs could also negatively affect post-transplantation recovery. Modulation of HO-1 expression may represent a feasible approach to limit rapamycin acute toxicity.

Effect of nitric oxide synthase inhibition and saline administration on blood pressure and renal sodium handling during experimental sepsis in rats.

Much effort has been made in recent years to clarify metabolic and renal function changes in sepsis. A number of studies performed in different models of sepsis have been described. One such model that is frequently used is cecal ligation and puncture (CLP) in rats. This model resembles human sepsis in several important aspects, such as an early phase of hyperdynamic, hypermetabolic sepsis followed by a late hypodynamic, hypometabolic phase. The present study evaluated the blood pressure (n = 5) and renal function changes during development of CLP renal failure and to determine the effects of NOS inhibition (L-NAME) and 0.15 M NaCl administration on tail blood pressure and renal function in randomly assigned five groups (n = 10 each): (1) Sham-operated, (2) Sham-operated L-NAME-treated, (3) CLP rats, (4) CLP L-NAME-treated, and (5) CLP 0.15 M NaCl-treated rats. The basal tail blood pressure was not significantly different among the four groups. One week later, arterial pressure was significantly increased in sham-operated L-NAME-treated rats (159 +/- 12 mmHg) compare with the other groups (118 +/- 9.0 mmHg in nontreated rats, p < 0.05). Blood pressure shows a slightly and not significant decrease up to 12h in L-NAME and 0.15 M NaCl treated rats, which in turn was followed by a significant reduced arterial pressure 18h after CLP in both groups (L-NAME: 96.0 +/- 3.6 mmHg, p < 0.05) and NaCl: 82.3 +/- 2.4 mmHg, p < 0.05) compared to sham-operated groups. The glomerular filtration rate estimated by CCr decreases significantly in the CLP untreated group (p < 0.001) and did not significantly differ from the sham-operated and L-NAME-treated groups (p = 0.4) during the studies of renal tubule sodium handling. On the other hand, subcutaneous 0.15 M NaCl administration prevented CCr decreases in CLP rats (p = 0.25). CLP increased the FENa in the sham-operated from: 857.2 +/- 85.1 delta%min(-1) to CLP: 1197.8 +/- 119.0 delta%min(-1). The high FENa to CLP was blunted and significantly reduced by previous systemic treatment of animals with L-NAME from sham-operated+L-NAME: 1368.0 +/- 72.0 delta%min(-1) to CLP+L-NAME: 1148.0 +/- 60.4 delta%min(-1) (p < 0.01). The enhanced FENa in the CLP group were accompanied by a significant increase in proximal sodium reabsorption rejection. The salient findings of the present study suggest that a decrease in the blood pressure and creatinine clearance caused by CLP may benefit from L-NAM and fluid resuscitation during initial bacteremia (first 12 h) by promoting an additional increase of tubule sodium reabsorption in the post-proximal segments of nephrons, but these therapies could not prevent acute renal failure after established endotoxemia.

[Isoamylases and isolipases values in the serum from patients wtih renal insufficiency]. / Valoración de isoamilasas e isolipasas en el suero de pacientes con insuficiencia renal.

OBJECTIVE: The aim of this study is to test the utility os serum isoamylases and isolipases as determined from patients with renal insufficiency. MATERIAL AND METHODS: Serum levels of isoamylases and isolipases were determined in a group of sixty-eight patients with renal disease, 32 of them suffering acute insufficiency and 36 with chronic renal failure undergoing regular hemodialysis, results obtained were compared from a population of 44 healthy adults. We used a new method for isolipases determination in serum based on its separation on agarose gel. Two forms of lipase, L1 and L2, were identified by this method and quantitated by densitometry. RESULTS: Were found a significant increase of pancreatic isoamylase P2 and P/S isoenzymatic ratio in acute patients (p < 0.001) as chronic (p < 0.05). In both groups, the isolipase L1 activity and L1/L2 isoform ratio were showed significantly elevated (p < 0.01). We studied the relationship between isoamylases and isolipases establishing the P2/L2 ratio (normal range < 0.6) showing, in the two pathologic groups, significantly elevated values compared with the control group (p < 0.001) and a positive and significant correlation between the P2/L2 and P/S isoform ratios (r = 0.76, p < 0.05 in acute patients; r = 0.58, p < 0.05 in chronic patients). CONCLUSION: The combined study of serum levels of isoamylases and isolipases could be an effective marker for diagnosis and evolution of associated pancreatitis with acute or chronic renal failure.