Effects of Pentoxifylline on Amikacin-Induced Nephrotoxicity in Rats

Prevention of nephrotoxicity induced by amikacin: The role of misoprostol, A prostaglandin E1 analogue

Amikacin (AK) is an aminoglycoside that is widely used to treat life-threatening Gram-negative infections, especially in intensive care units. Despite its wide clinical indications, AK causes serious side effects such as kidney toxicity. AK was found to lead to tissue damage primarily through apoptosis and oxidative stress. Therefore, it was investigated whether misoprostol (MP), which has antioxidant and antiapoptotic properties, had a beneficial effect on kidney damage caused by AK. It was observed that kidney injury molecule-1 (KIM-1) mRNA, blood urea nitrogen (BUN), creatinine (Cr), NADPH oxidase-4 (NOX-4) and Caspase-3 (CAS-3) levels increased in the AK-treated group in comparison with the control group, while uric acid, albumin, and total protein levels were decreased. In rats that were treated with AK+MP, the levels of KIM-1 mRNA, BUN, Cr, NOX-4 and CAS-3 were significantly decreased in comparison with the AK group, while uric acid, albumin and total protein levels increased. According to the obtained results, MP was found to be quite effective in the protection of kidneys from the toxic effects of AK.

Antioxidative and Anti-Inflammatory Protective Effects of β-Caryophyllene against Amikacin-Induced Nephrotoxicity in Rat by Regulating the Nrf2/AMPK/AKT and NF-κB/TGF-β/KIM-1 Molecular Pathways

Herein, the molecular pathogenic pathways implicated in renal injury triggered by amikacin (AK), together with the alleviating actions of β-caryophyllene (BCP), were investigated. Adult male Wistar rats (n = 32) were disseminated to the four following groups (n = 8/group): normal group, positive control animals (PC) that received AK intraperitoneal injections for 14 days (500 mg/kg/day), and rats that received AK simultaneously with small (200 mg/kg/day) and high doses (400 mg/kg/day) of BCP. The PC renal tissues revealed abnormal histology alongside increased apoptosis and significantly elevated serum creatinine and urea with marked proteinuria and oliguria relative to the normal rats. Moreover, renal tissues from the PC animals also showed substantial upregulations in NF-κB/TGF-β/KIM-1, whilst Nrf2/AMPK/AKT/PCNA declined, at the gene and protein levels in comparison to the normal rats. Additionally, the levels of markers of oxidative stress (MDA/H₂O₂/protein adducts) and inflammation (TNF-α/IL-1β/IL-6/IL-18/TLR/HSP25) were substantially higher in the PC renal specimens, whereas the antioxidants (GSH/GPx/SOD1/CAT) and interleukin-10 decreased, relative to the NC group. Both BCP protocols improved the biochemical markers of renal functions, alleviated renal histopathology and apoptosis, and decreased NF-κB/TGF-β/KIM-1 alongside the concentrations of oxidative stress and proinflammatory markers, whilst promoting Nrf2/AMPK/AKT/IL-10/PCNA and the targeted antioxidants. However, the improving effects in the high-dose regimen were markedly stronger than those observed in animals treated with low dose of BCP. In conclusion, the present report is the first to connect NF-κB/TGF-β/KIM-1 proinflammatory and Nrf2/AMPK/AKT antioxidative stress pathways with the pathogenesis of AK-induced nephrotoxicity. Additionally, the current report is the first to disclose alleviating activities for BCP against AK-triggered nephrotoxicity by modulating multiple antioxidative stress with anti-inflammatory molecular pathways.

Thymoquinone ameliorates amikacin induced oxidative damage in rat brain tissue

We investigated the potential neuroprotective effects of thymoquinone (TQ) on amikacin (AK) induced oxidative damage in rat brain. We used 21 male rats divided randomly into three equal groups. The control group was injected intraperitoneally (i.p.) with 0.5 ml 0.9% aqueous NaCl and given 1 ml 0.9% aqueous NaCl orally. The AK group was administered 1.2 g/kg aqueous AK i.p. as a single dose on the day 3 of the study. The AK + TQ group was given a single 1.2 g/kg dose of AK i.p. on the day 3 of the study plus 40 mg/kg/day TQ by oral gavage daily. Treatment with TQ increased serum ferritin and decreased serum calcium levels significantly. TQ also decreased NADPH oxidase-2, NADPH oxidase-4, and caspase-3 levels. Decreased malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) and catalase (CAT) activities were detected in the AK + TQ group compared to the AK group. TQ administration inhibited lipid peroxide formation and blocked oxidative reactions, which reduced the MDA level and increased SOD and CAT activities induced by AK. Oxidative damage caused by AK was ameliorated by TQ treatment owing to its antioxidative and anti-apoptotic effects. TQ may be a potential therapeutic agent for reducing the severity of AK induced oxidative damage to the brain.

The nephroprotective properties of taurine-amikacin treatment in rats are mediated through HSP25 and TLR-4 regulation

Amikacin (AMK) is one of the most effective aminoglycoside antibiotics. However, nephrotoxicity is a major deleterious and dose-limiting side effect associated with its clinical use especially in high dose AMK-treated patients. The present study assessed the ability of taurine (TAU) to alleviate or prevent AMK-induced nephrotoxicity if co-administrated with AMK focusing on inflammation, apoptosis, and fibrosis. Male Sprague Dawley rats were assigned to six equal groups. Group 1: rats received saline (normal control), group 2: normal rats received 50 mg kg^-1 TAU intraperitoneally (i.p.). Groups 3 and 4: received AMK (25 or 50 mg kg^-1; i.p.). Groups 5 and 6: received TAU (50 mg kg^-1; i.p.) concurrently with AMK (25 or 50 mg kg^-1; i.p.) for 3 weeks. AMK-induced nephrotoxicity is evidenced by elevated levels of serum creatinine (CRE), blood urea nitrogen (BUN), and uric acid (UA). Histopathological investigations provoked damaging changes in the renal tissues. Heat shock proteins (HSP)25 and Toll-like receptor-4 (TLR-4) elevated levels were involved in the induction of inflammatory reactions and focal fibrosis. The improved activation of TLR-4 may stimulate monocytes to upgrade Interleukin (IL)-18 production rather than IL-10. TAU proved therapeutic effectiveness against AMK-induced renal toxicity through downregulation of HSP25, TLR-4, caspase-3, and IL-18 with up-regulation of IL-10 levels.

Phosphodiesterase (1, 3 & 5) inhibitors attenuate diclofenac-induced acute kidney toxicity in rats

Diclofenac, one of the most commonly used non-steroidal anti-inflammatory drugs, leads to severe adverse effects on the kidneys. The aim of the present study was to investigate the potential pretreatment effect of phosphodiesterase (1, 3 & 5) inhibitors on diclofenac-induced acute renal failure in rats. Rats orally received pentoxifylline (100 mg/kg), vinpocetine (20 mg/kg), cilostazol (50 mg/kg), or sildenafil (5 mg/kg) once per day for 6 consecutive days. Diclofenac (15 mg/kg) was injected on day-4, -5 and -6 in all groups except normal control group. The used phosphodiesterase inhibitors significantly reduced the diclofenac-induced elevation in the serum levels of blood urea nitrogen, creatinine and cystatin C. Moreover, the renal tissue contents of tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB as well as the protein expression of toll-like receptor (TLR) 4 and high mobility group box (HMGB) 1 were markedly reduced by the used phosphodiesterase inhibitors, as compared to the diclofenac control. This was reflected on the marked improvement in histopathological changes induced by diclofenac. Sildenafil showed the best protection regarding TNF-α and NF-κB, while cilostazol showed the best results regarding TLR4, HMGB1 and histopathological examination. This study revealed the good protective effect of these phosphodiesterase inhibitors against diclofenac-induced acute renal failure.

A randomized double-blinded placebo-controlled clinical trial on protective effects of pentoxifylline on gentamicin nephrotoxicity in infectious patients

BACKGROUND AND OBJECTIVE

Renal toxicity has limited gentamicin use in clinical practice. The aim of the present clinical trial was to assess the possible nephroprotective effects of pentoxifylline (PTX) against gentamicin nephrotoxicity.

MATERIALS AND METHODS

A multicenter, randomized, double-blind, placebo-controlled clinical trial was conducted on patients who had the indication for systemic gentamicin for at least 7 days. Sixty people were selected and randomly assigned. For patients in the intervention and control groups, 400 mg PTX sustained release tablet and placebo were given orally three times daily, respectively. Demographic, clinical, laboratory, and therapeutic information of patients were recorded. malondialdehyde (MDA) and tumor necrosis factor-alpha (TNF-α) levels in serum were measured on days 0 and 7.

RESULTS

The incidence of nephrotoxicity in the placebo group was 19.6 times higher than that in the PTX group (OR = 19.6, 95%CI = 3.08-114.32; P value = 0.001). The mean ± SD time onset of ATN was 4.00 ± 2.32 and 5.58 ± 1.59 days in PTX and placebo recipients, respectively (P value < 0.001). No significant differences were observed for hypokalemia, hypomagnesemia, potassium and magnesium wasting between the two groups. The mean ± SD levels of serum MDA and TNF-α at day 7 were significantly lower in the PTX compared to those in the placebo group (P value < 0.001 for both indexes).

CONCLUSION

The co-administration of 400 mg PTX orally three times daily along with gentamicin was both well-tolerated and effective in preventing the nephrotoxicity of gentamicin in patients with different infectious diseases.

Thymoquinone protection from amikacin induced renal injury in rats

We investigated whether thymoquinone (TQ) exerts a beneficial effect on renal injury due to amikacin (AK) administration in rats. To generate kidney damage with AK, a single 1.2 g/kg dose of AK was administered intraperitoneally. TQ was administered orally to the AK treated group at a dose of 40 mg/kg for five days. At the end of the experiment, rats were sacrificed and blood samples were used to measure blood urea nitrogen (BUN) and creatinine (Cr) levels. Kidney samples were taken to measure the oxidative stress biomarker, malondialdehyde (MDA), and expression of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT). Because reactive oxygen species (ROS) and apoptosis contribute to tissue damage associated with NADPH oxidase (NOX), we also investigated NOX-2, NOX-4 and apoptosis marker, caspase-3, expression using immunohistochemistry. MDA, BUN, Cr, NOX-2, NOX-4 and caspase-3 production were increased, and SOD and CAT were decreased in the AK treated group compared to controls. MDA, BUN, Cr, NOX-2, NOX-4 and caspase-3 levels were decreased, and SOD and CAT levels were increased in TQ + AK treated rats compared to AK treated animals. TQ appears to protect the kidney from the toxic effects of AK.

Effect of pentoxifylline on kidney damage induced by nitrosamine in male rats

Nitrosamines are well-known carcinogenic agents. Humans are exposed to nitrosamines in various ways, the most important of which is the diet. Pentoxifylline is a xanthine derivative, which is used as a drug that inhibits inflammatory factors, reduces blood viscosity, improves peripheral blood flow, and increases oxygenation of tissue. This study was designed to evaluate the effects of pentoxifylline against damage induced by nitrosamine to the kidneys of rats. In this study, 48 male rats were randomly assigned to 8 groups: control normal group and nitrosamine control treated group (40 mg/kg); pentoxifylline groups (25, 50, 100 mg/kg) and nitrosamine + pentoxifylline treated groups (25, 50, 100 mg/kg). Treatments were administered either intraperitoneally (nitrosamine) or orally (pentoxifylline) on a daily basis for 28 days. The normalized kidney weight, glomeruli characteristics, thiobarbituric acid reactive species, antioxidant capacity, kidney function indicators, and serum nitrite oxide levels were investigated. Nitrosamine administration increased kidney malondialdehyde (MDA) level, kidney weight, blood urea nitrogen (BUN), creatinine, and nitrite oxide levels and decreased significantly glomeruli number and tissue ferric reducing/antioxidant power (FRAP) level compared to the control normal group (P < 0.05). The pentoxifylline and pentoxifylline + nitrosamine treatments reduced BUN, kidney MDA level, creatinine, glomerular diameter, and nitrite oxide levels significantly at all doses and increased the glomeruli number, kidney weight, and tissue FRAP level compared to the nitrosamine control group (P < 0.05). It seems that pentoxifylline administration improved kidney injury induced by nitrosamine in rats.

Protective effect of pentoxifylline on amikacin-induced ototoxicity

We conducted an animal experiment to assess the effect of adding pentoxifylline to amikacin to prevent amikacin-induced ototoxicity. This research was conducted on 24 rats arranged in four groups of 6. One group was injected with 200 mg/kg of intramuscular amikacin once daily for 14 days (AMK-only group). Another received 25 mg/kg of oral pentoxifylline and 200 mg/kg of intramuscular amikacin once daily for 14 days (PTX-AMK 14/14 group). A third group received 25 mg/kg of oral pentoxifylline for 28 days and 200 mg/kg of intramuscular amikacin once daily for 14 days on days 15 through 28 of the pentoxifylline regimen (PTX-AMK 28/14 group). Finally, a control group was administered 1 ml/day of 0.5% carboxymethyl cellulose for 28 days. Transient otoacoustic emissions (TOAEs) were statistically analyzed and serum urea and creatinine levels were measured before and after treatment. We found no significant differences in TOAEs among the groups at the study's onset, but after the experiment, TOAEs disappeared in all frequency bands in the AMK-only and PTX-AMK 14/14 groups. However, TOAEs were preserved in the PTX-AMK 28/14 group. In addition, the serum urea and creatinine levels in the PTX/AMK 28/14 group were significantly lower than the levels in the other two treatment groups (p < 0.05 for all), but not significantly different from those of the control group. We conclude, therefore, that 28 days of pentoxifylline treatment exerted a protective effect against amikacin-induced ototoxicity in rats.

Protective effect of dexpanthenol against nephrotoxic effect of amikacin: An experimental study

BACKGROUND

Amikacin has the largest spectrum among aminoglycosides, its nephrotoxic effect limits its utilization. Our purpose in this study is to review the protective effect of dexpanthenol against the nephrotoxic effect of amikacin, accompanied with histopathological and biochemical parameters.

METHODS

32 rats were randomly separated into four groups with eight in each (amikacin (1.2mg/kg/day), amikacin (1.2mg/kg/day)+dexpanthenol (500mg/kg/day), dexpanthenol (500mg/kg/day) and control). In order to assess the oxidative balance and renal damage between groups, biochemical parameters (total antioxidant capacity (TAS), total oxidant stress (TOS), catalase (CAT), paraoxonase (PON), arylesterase (ARES), urea, and creatinin) were studied from the blood samples. At the end of the 14th day, renal tissues were reviewed blindly by a pathologist.

RESULTS

TOS and oxidative stress index (OSI) values were significantly lower in the group which was administered with dexpanthenol+amikacin compared to the group which only received amikacin (respectively, p=0.001, p=0.002). Antioxidant biochemical parameters (TAS, CAT, PON, and ARES) were significantly higher in the group which was administered with dexpanthenol+amikacin compared to the group administered only with amikacin (respectively, p=0.007, p=0.001, p=0.003, p=0.003). Urea and creatitin values were found to be significantly lower in the group which was administered with dexpanthenol+amikacin compared to the group administered only with amikacin (respectively, p=0.002, p=0.001). Histopathologic changes such as glomerular and tubular epithelium changes and interstitial edema were clearly observed in the group administered only with amikacin, such findings were insignificant in the group administered with dexpanthenol+amikacin.

CONCLUSION

It was revealed with biochemical and histopathologic data that nephrotoxic effects created by amikacin administration can be limited with dexpanthenol by using them together, and further advanced clinical studies are required.

Effects of pentoxifylline and alpha lipoic acid on methotrexate-induced damage in liver and kidney of rats

The aim of the current study was to investigate the probable protective effects of Pentoxifylline (PTX) and Alpha Lipoic Acid (ALA), which display anti-oxidative efficacy against hepatotoxicity and nephrotoxicity, those being the major side effects of Methotrexate (MTX). Rats were divided into four groups: a control group; MTX (20mg/kg/day) group; MTX+PTX (20mg/kg/day+50mg/kg/day) group; and an MTX+ALA (20mg/kg/day+100mg/kg/day) group. At the end of the experiment, biochemical, histochemical and immunohistochemical analyses were performed on liver and kidney tissues of rats. We determined Glutathione Peroxidase (GSH-Px), Superoxide Dismutase (SOD), Catalase (CAT), Malondialdehyde (MDA), Nitric Oxide (NO) and Xanthine Oxidase (XO) levels in the liver and kidney. Moreover, Gamma Glutamyl Transferase (GGT), Direct Bilirubin (DBil), Blood Urea Nitrogen (BUN), and urea levels were measured in the serum. The histochemical evaluation revealed a significant decrease in MTX caused damage in the PTX- and ALA-treated groups (especially in ALA group). On the other hand, the immune staining of iNOS and TNF-α were observed most densely in the MTX group, while the density decreased in the PTX- and ALA-administered groups. We determined increased GGT, BUN, urea and levels of CAT, MDA, NO, and XO values in both groups, while GSH-Px (an increase in liver tissue) and DBil levels were decreased in the group that received MTX. However, we determined decreased SOD levels in liver tissue. In the PTX and ALA groups, the levels of GGT, BUN and urea as well as the levels of CAT, MDA, NO and XO decreased (SOD increased in the liver tissue), and the levels of GSH-Px and DBil increased. In conclusion, it can be stated that, although ALA is more effective in preventing the toxic effects of MTX on the liver and kidney, PTX also has a preventive effect. As a result, we can readily suggest that ALA and PTX can have protective effects by decreasing MDA, NO, BUN and urea values as antioxidants against MTX-induced damage in liver and kidney of rats.

Anti-inflammatory effects of vinpocetine on the functional expression of nuclear factor-kappa B and tumor necrosis factor-alpha in a rat model of cerebral ischemia-reperfusion injury

OBJECTIVE

The restoration of blood flow to the brain after ischemic stroke prevents further, extensive damage but can result in reperfusion injury. The inflammation response is one of many factors involved in cerebral ischemia-reperfusion injury. This study investigated the use of vinpocetine, a drug used to treat cognitive impairment, to explore its effects on inflammation in a rat model of cerebral ischemia-reperfusion.

METHODS

Wistar rats were randomly assigned to a control group, (n=40) a cerebral ischemia-reperfusion group (n=52) and a vinpocetine cerebral ischemia-reperfusion group (n=52). A model of middle cerebral artery occlusion was induced for 2h followed by reperfusion and the infarct size was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining 6h, 24h, 3 days, and 7 days after reperfusion. The dry-wet weight method was used to measure brain water content and evaluate the extent of brain edema. Immunohistochemistry and in-situ hybridization were used to detect the expression of NF-κB and TNF-α.

RESULTS

The NF-κB levels in ischemic brain tissue increased 6h after reperfusion and the TNF-α levels increased at 24h, both reached their peaks at day 3 then decreased gradually, but remained above the controls at day 7. Vinpocetine decreased the levels of NF-κB and TNF-α 24h and 3 days after reperfusion.

CONCLUSION

NF-κB and TNF-α is associated with changes in brain edema and infarct volume. Vinpocetine decreases the expression of NF-κB and TNF-α and inhibits the inflammatory response after cerebral ischemia-reperfusion.

Effects of pentoxifylline on gentamicin-induced nephrotoxicity

We aimed to investigate the underlying mechanisms responsible for the renoprotective effects of pentoxifylline (PTX) in gentamicin (GEN)-induced nephropathy. On this purpose, 26 female Wistar rats (200-250 g) were included and four groups were formed. The first one was the control group (n:5). The rats in other groups (n:7 for each) received 50 mg/kg twice daily intraperitoneal (i.p.) PTX, 100 mg/kg i.p. GEN and both GEN and PTX at the same doses for consecutive 8 days, respectively. Rats were weighed both at the beginning and end of the study. After the last dose, 24-hour urines were collected and the rats were sacrificed. Blood samples and kidney tissues were obtained for biochemical, histological, oxidative stress, and apoptotic parameters. Body weights were similar in all groups at the beginning of the study. Rats in GEN group had significant weight loss, tubular damage, and increased apoptosis, while GEN + PTX group had significantly better outcomes. Scr, urinary protein/creatinine, and TBARS levels were significantly higher and Ccr and SOD levels were significantly lower in GEN and GEN + PTX groups in comparison to control and PTX groups, but the levels were similar between GEN and GEN + PTX groups. In conclusion, concomitant administration of PTX provides renoprotection via suppressing apoptosis in GEN-induced nephropathy.

Protective effect of pentoxifylline on amikacin-induced ototoxicity in rats

PURPOSE

This experimental study was performed to investigate the possible protective effect of pentoxifylline (PTX) on amikacin-induced ototoxicity in rats.

MATERIALS AND METHODS

In this study, 21 healthy female rats were randomly assigned to 1 of 3 groups: the amikacin group (n = 8), the amikacin + PTX group (n = 8), and the control group (n = 5). The amikacin group received amikacin (200 mg·kg(-1)·day(-1)) intramuscularly once daily for 14 days. The amikacin + PTX group received intramuscular injections of amikacin (200 mg·kg(-1)·day(-1)) once daily for 14 days and PTX (25 mg·kg(-1)·day(-1)) once daily via gastric gavage for 14 days. The control group received saline solution (1 mL·day(-1) intraperitoneal injections) once daily for 14 days. The hearing levels of the rats were evaluated using distortion product otoacoustic emissions before and after treatment.

RESULTS

The distortion product otoacoustic emissions' amplitude levels (decibel, sound pressure levels) measured before and after treatment at frequencies of 4000, 6000, and 8000 Hz revealed that values of the amikacin group dropped significantly at the end of treatment (P < .01). In contrast, the amikacin + PTX and the control groups showed no significant difference at the end of the treatment compared with the initial measurements (P > .05).

CONCLUSION

The results showed that PTX has protective effects on hearing functions in amikacin-induced ototoxicity in rats.

The effect of grape seed proanthocyanidin extract in preventing amikacin-induced nephropathy

BACKGROUND/AIMS

Nephrotoxicity induced by aminoglycosides (AGs) limits their clinical use. As yet, no molecules have been approved to prevent AG nephropathy. We aim to investigate the effectiveness of grape seed proanthocyanidin extract (GSPE) in the prevention of amikacin (AK)-induced nephrotoxicity.

METHODS

A total of 24 rats were allocated into control, GSPE, AK, and AK + GSPE groups. While 1 mL saline was administered for 6 days in control and AK groups, 100 mg/kg GSPE was administered in GSPE and AK + GSPE groups. On day 7, intraperitoneal (i.p.) saline was administered in control and GSPE groups, while 1.2 g/kg i.p. AK was administered in AK and AK + GSPE groups. The experiment was terminated on day 9. Blood samples were taken for the measurement of renal functions. Renal tissues of the rats were removed for the analysis of malondialdehyde (MDA), total oxidant system (TOS), total antioxidant system, oxidative stress index (OSI), and for histopathological examination.

RESULTS

MDA level was found to be lower in GSPE group compared with other study groups. There was significantly more renal histopathological damage and higher blood urea nitrogen, creatinine, TOS, OSI, and MDA levels in the AK group compared with the control and AK + GSPE groups. The same parameters showed significant improvement in AK + GSPE group compared with AK group.

CONCLUSION

Our findings demonstrate for the first time that GSPE reduces oxidative damage in AK nephropathy and provides biochemical and renal histopathological improvements.

Effects of aspirin and nimesulide on tissue damage in diabetic rats

This study was designed to compare the effect of Aspirin (AS) and Nimesulide (NM) on renal failure and vascular disorder in streptozotocin (STZ)-induced diabetic rats. Rats were divided into four groups; control, diabetic rats, diabetic rats plus AS and diabetic rats plus NM, which are COX inhibitors. The renal and aorta tissues morphology were investigated by light microscopy. Trunk blood was also obtained to determine plasma lipid peroxidation product malondialdehyde (MDA) and plasma activity of antioxidant enzymes. MDA levels were increased in the diabetic rats when compared to the control group. AS and NM administration caused a significant decrease in MDA production. Morphological damage in diabetic rats was severe in the kidney and in the aorta tissue. Treatment of AS reduced these damages, but NM did not exert positive effect on these damages in diabetic rats. As a result, although both AS and NM corrected lipid peroxidation parameters such as MDA via their antioxidant properties, only AS ameliorated pathological alteration in tissues. These findings indicate that there may be another mechanism in beneficial effect of AS in diabetic rats.

Pentoxifylline in ischemia-induced acute kidney injury in rats

Ischemia is an important cause of acute kidney injury (AKI). Pentoxifylline has been shown to improve tissue oxygenation and endothelial function and inhibit proinflammatory cytokine production. The aim of this study was to evaluate a possible renal protective effect of pentoxifylline against ischemia by measuring mitochondrial respiratory metabolism as an index of cell damage. Rats were submitted to right nephrectomy. The left kidney was submitted to ischemia by clamping the renal artery for 45 minutes. Immediately after release of the clamp, 1 mL of a solution containing 20 mg of pentoxifylline/mL was injected intravenously, while a control group received 1 mL of normal saline intravenously. Five minutes after the injection, the left kidney was removed, homogenized, and subjected to refrigerated differential centrifugation. Mitochondrial respiratory metabolism was measured polarographically. The mitochondria isolated from the kidneys of saline-treated rats had an endogenous respiration of 9.20 +/- 1.0 etamol O(2)/mg protein/min compared to 8.9 +/- 1.4 etamol O(2)/mg protein/min in the pentoxifylline-treated rats (p > 0.05). When stimulated by sodium succinate, the respiratory metabolism increased in a similar fashion in both groups of animals: 17.9 +/- 2.3 and 18.1 +/- 2.1 etamol O(2)/mg protein/min in the untreated and pentoxifylline-treated groups, respectively (p > 0.05). In the present study, pentoxifylline was not found to exert any protective effect on the kidney. It is possible that at the time of pentoxifylline administration, the mitochondria had already been damaged by the process of ischemia, and its effect may have been insufficient to reverse cell damage.