Renoprotective effect of N-acetylcysteine depends upon the severity of the ischemia reperfusion injury

Acute kidney injury (AKI) is a common complication in seriously ill patients, while renal ischemia-reperfusion (I/R) injury is the most frequent event in this oxidative renal injury. N-acetylcysteine (NAC) is a small molecule containing a thiol group that has antioxidant properties, promoting detoxification and acting directly as a free radical scavenger. In this study, the protective effect of NAC was investigated in short-term (30 min) and long-term (45 min) ischemic AKI. This was achieved via clamping of the renal artery for 30 or 45 min in Wistar rats to induce I/R injury. AKI worsened with a longer period of ischemia (45 compared to 30 min) due to probable irreversible damage. Preconditioning with NAC in short-term ischemia improved renal blood flow and increased creatinine clearance by reducing oxidative metabolites and increasing antioxidant capacity. Otherwise, NAC did not change these parameters in the long-term ischemia. Therefore, this study demonstrated that the period of ischemia determines the severity of the AKI, and NAC presented antioxidant effects in short-term ischemia but not in long-term ischemia, confirming that there is a possible therapeutic window for its renoprotective effect.

Endothelin-1 receptor antagonists protect the kidney against the nephrotoxicity induced by cyclosporine-A in normotensive and hypertensive rats

Cyclosporin-A (CsA) is an immunosuppressant associated with acute kidney injury and chronic kidney disease. Nephrotoxicity associated with CsA involves the increase in afferent and efferent arteriole resistance, decreased renal blood flow (RBF) and glomerular filtration. The aim of this study was to evaluate the effect of Endothelin-1 (ET-1) receptor blockade with bosentan (BOS) and macitentan (MAC) antagonists on altered renal function induced by CsA in normotensive and hypertensive animals. Wistar and genetically hypertensive rats (SHR) were separated into control group, CsA group that received intraperitoneal injections of CsA (40 mg/kg) for 15 days, CsA+BOS and CsA+MAC that received CsA and BOS (5 mg/kg) or MAC (25 mg/kg) by gavage for 15 days. Plasma creatinine and urea, mean arterial pressure (MAP), RBF and renal vascular resistance (RVR), and immunohistochemistry for ET-1 in the kidney cortex were measured. CsA decreased renal function, as shown by increased creatinine and urea. There was a decrease in RBF and an increase in MAP and RVR in normotensive and hypertensive animals. These effects were partially reversed by ET-1 antagonists, especially in SHR where increased ET-1 production was observed in the kidney. Most MAC effects were similar to BOS, but BOS seemed to be better at reversing cyclosporine-induced changes in renal function in hypertensive animals. The results of this work suggested the direct participation of ET-1 in renal hemodynamics changes induced by cyclosporin in normotensive and hypertensive rats. The antagonists of ET-1 MAC and BOS reversed part of these effects.

O uso de fitoterápicos orientais nas lesões renais: revisão integrativa / The use of oriental herbal medicines in acute kidney injury: an integrative review

RESUMO As disfunções renais constituem um problema de saúde global com alta prevalência e custos com internações hospitalares. A fitoterapia chinesa possui tradição milenar na prevenção e tratamento dessas disfunções e conta com o incentivo da OMS às práticas integrativas e complementares; o número de pesquisas experimentais cresceu substancialmente. Esta revisão tem como objetivo levantar os estudos que relacionem o tratamento das disfunções renais com fórmulas fitoterápicas pertencentes à medicina tradicional chinesa; identificar os modelos de lesão renal adotados, as ervas e as doses empregadas, bem como a eficácia do tratamento. Os artigos foram selecionados nas bases Pubmed e Lilacs com os seguintes termos: medicina tradicional chinesa, rim, e erva, em modelos animais no período de 10 anos. Foram selecionados 12 estudos sendo que em 11 o fitoterápico conseguiu prevenir ou melhorar a lesão renal; em 6 estudos foram utilizadas fórmulas contendo associação de plantas; e em outros 6, o medicamento alopático foi o controle. Os modelos de lesão mais utilizados foram de nefrectomia e nefrotoxicidade enquanto a administração foi a via gavagem. A fitoterapia pode atuar como terapia complementar no tratamento das lesões renais, possui baixo custo e pode ser associado a intervenções alopáticas. Porém, é preciso conhecer profundamente os riscos, as possíveis interações, a toxicidade, e os mecanismos de ação, além dos possíveis efeitos adversos do uso dessas ervas.

ABSTRACT Kidney dysfunction consists in a global healthcare problem with high prevalence and hospitalization costs. Chinese phytotherapy is part of ancient tradition used to treat and prevent renal injury. As a result of WHO incentives for integrative and complementary practices, the number of experimental researches has increased substantially. The aim of this review is to make a survey of studies that related traditional Chinese medicine, phytotherapy and kidney injuries; and identify methodology, plants, doses and their efficacy. Articles were selected using Pubmed and Lilacs database with the following terms: traditional Chinese medicine, kidney and in animal models for a period of 10 years. In 11 of the 12 studies selected, Chinese herbal medicine could prevent or improve kidney disease. 6 researches used combined herbs formulas and in the other 6 ones allopathic medicine were the control group; nephrectomy and nephrotoxicity were the most frequently used lesion models and the medicines administration was through oral gavage method. Phytotherapy can be used as a complementary therapy in kidney injuries treatments, shows low cost and can be associated with allopathic therapies. However it is necessary to know the risks, interactions, toxicity, mechanisms of action and adverse effects of medicinal plants.

Effect of cyclooxygenase inhibitors on gentamicin-induced nephrotoxicity in rats

The frequent use of nonsteroidal anti-inflammatory drugs (NSAID) in combination with gentamicin poses the additional risk of nephrotoxic renal failure. Cyclooxygenase-1 (COX-1) is the main enzyme responsible for the synthesis of renal vasodilator prostaglandins, while COX-2 participates predominantly in the inflammatory process. Both are inhibited by non-selective NSAID such as indomethacin. Selective COX-2 inhibitors such as rofecoxib seem to have fewer renal side effects than non-selective inhibitors. The objective of the present study was to determine whether the combined use of rofecoxib and gentamicin can prevent the increased renal injury caused by gentamicin and indomethacin. Male Wistar rats (250-300 g) were treated with gentamicin (100 mg/kg body weight, ip, N = 7), indomethacin (5 mg/kg, orally, N = 7), rofecoxib (1.4 mg/kg, orally, N = 7), gentamicin + rofecoxib (100 and 1.4 mg/kg, respectively) or gentamicin + indomethacin (100 and 5 mg/kg, respectively, N = 8) for 5 days. Creatinine clearance and alpha-glutathione-S-transferase concentrations were used as markers of renal injury. Animals were anesthetized with ether and sacrificed for blood collection. The use of gentamicin plus indomethacin led to worsened renal function (0.199 ± 0.019 ml/min), as opposed to the absence of a nephrotoxic effect of rofecoxib when gentamicin plus rofexicob was used (0.242 ± 0.011 ml/min). These results indicate that COX-2-selective inhibitors can be used as an alternative treatment to conventional NSAID, especially in situations in which risk factors for nephrotoxicity are present.