Gentamicin nephrotoxicity in rat: some biochemical correlates

Nephroprotective Effect of the Leaf Extract of Ajuga remota Benth Against Gentamicin-Induced Nephrotoxicity in Swiss Albino Mice

Background

Drug-induced kidney injury was among the most common renal damages, from which gentamicin occupies around 25% of this injury. Gentamicin-induced renal damage is caused by increased free radicals with subsequent amplified inflammation. Ajuga remota leaf extract has many phytochemicals with antioxidant activities, which may improve gentamicin-induced renal damage. Thus, we aimed to investigate the nephroprotective effect of Ajuga remota leaf methanolic extract on gentamicin-induced nephrotoxicity in Swiss Albino Mice.

Methods

An experimental study design was used on 30 experimental mice randomly allocated in six groups: Group I, II, II, IV, and VI, among which mice were given only distilled water, only gentamicin, 600 mg/kg Ajuga remota leaf extract only, gentamicin along with 200 mg/kg extract, gentamicin with 400 mg/kg extract and gentamicin with 600 mg/kg extract, respectively. At the end of the experiment, the mice were sacrificed after being anaesthetized, and blood samples were collected through a cardiac puncture for renal function tests while the kidneys were removed for histopathological evaluation. The data were entered into Epidata version 4.6 and exported to SPSS version 25 for further analysis using one-way analysis of variance. Statistical significance was set at p < 0.05.

Results

Group II mice had significantly higher levels of serum creatinine and blood urea levels compared to group I and III. The body weight of the mice in group V and group VI showed a significant increase compared with Group II. Serum creatinine and blood urea levels were reduced significantly in the Ajuga remota leaf extract administered group of mice compared to group II. Abnormal kidney architectural changes were seen among group II mice; however, those changes were improved after administration of Ajuga remota leaf methanolic extract.

Conclusion

Methanol extract of Ajuga remota leaf provided effective protection against gentamicin-induced oxidative renal damage through its antioxidant effects.

Renoprotective Effect of Fucoidan from Seaweed Sargassum angustifolium C. Agardh 1820 on Gentamicin-Induced Nephrotoxicity: From Marine Resources to Therapeutic Uses

Background: Nephrotoxicity is a major side effect of aminoglycoside antibiotics, caused by oxidative damage and inflammation. Fucoidan, a group of sulfated polysaccharides derived from different species of brown algae, are well recognized for their antioxidant and anti-inflammatory activities. Objectives: In the present study, we aimed to investigate, for the first time, the efficacy of fucoidan extracted from Sargassum angustifolium C. Agardh 1820 against gentamicin-induced nephrotoxicity in rats. Methods: Twenty-eight male Wistar rats were divided into 4 groups of control, gentamicin (100 mg/kg), and gentamicin plus 50- and 100-mg/kg/day fucoidan pretreatment. In the end, all rats were killed, and then urine, blood, and tissue samples were prepared. Kidney weight (KW), body weight (BW), and 24-hour urine volume, as well as serum creatinine (Cr), blood urea nitrogen (BUN), Cr clearance, and malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity, were measured. Kidney samples were also evaluated for histopathological changes. Results: Gentamicin significantly increased KW, KW/BW ratio, 24-hour urine volume, serum Cr, MDA, and BUN levels; however, fucoidan pretreatment, especially at a dose of 50 mg/kg, significantly returned these variables near to the control group values. Gentamicin also decreased BW gain, Cr clearance, SOD activity, and the degree of renal tissue damage compared to the control group, while treatment with fucoidan significantly reversed these alterations. Conclusions: The results show that fucoidan from S. angustifolium C. Agardh 1820 ameliorates gentamicin-induced nephrotoxicity by alleviating oxidative stress and augmenting antioxidant enzymes activity in renal tissue, suggesting the potential use of this fucoidan in a clinical setting.

Nephroprotective role of diosgenin in gentamicin-induced renal toxicity: biochemical, antioxidant, immunological and histopathological approach

Background

Aminoglycoside antibiotics, gentamicin (GM) owns the utmost nephrotoxic potential than other antibiotics from the same category. To the other side, diosgenin (DG) showed the antioxidant and anti-inflammatory property.

Results

The present study was aimed to explore the nephroprotective effect of diosgenin on gentamicin-induced renal toxicity in Wistar rats. Wistar albino rats were divided into six groups (n = 6): Normal control (NC), Nephrotoxicity control (GM), DG (20 mg/kg), DG (40 mg/kg), DG (80 mg/kg), accordingly. After the treatment, the nephroprotective effects of DG were assessed by measuring serum levels of creatinine (Cr), blood urea nitrogen (BUN), total proteins (TP), albumin and urea levels. Urine volume, proteins, electrolyte levels, creatinine clearance were also evaluated in urine samples. Oxidative stress was evaluated through the measurement of antioxidant stress markers in the kidney tissue. Changes in body weight and kidney weight were also recorded along with a histopathological examination of kidney sections. For evaluation of inflammation, TNF-α and IL-1β levels were measured in the blood serum using ELISA kits. GM intoxication induced elevated serum creatinine, BUN, urea, albumin and TP levels, urine electrolytes levels, pro-inflammatory cytokines, antioxidant parameters which were found to be decreased significantly in a dose-dependent manner in rat groups received DG which was also evidenced by the histological observations.

Conclusion

DG showed a significant nephroprotective effect in a dose-dependent manner by ameliorating the GM induced nephrotoxicity in Wistar rats.

Skeletal Muscle-Derived Stem/Progenitor Cells: A Potential Strategy for the Treatment of Acute Kidney Injury

Skeletal muscle-derived stem/progenitor cells (MDSPCs) have been thoroughly investigated and already used in preclinical studies. However, therapeutic potential of MDSPCs isolated using preplate isolation technique for acute kidney injury (AKI) has not been evaluated. We aimed to characterize rat MDSPCs, compare them with bone marrow mesenchymal stem cells (BM-MSCs), and evaluate the feasibility of MDSPCs therapy for gentamicin-induced AKI in rats. We have isolated and characterized rat MDSPCs and BM-MSCs. Characteristics of rat BM-MSCs and MDSPCs were assessed by population doubling time, flow cytometry, immunofluorescence staining, RT-PCR, and multipotent differentiation capacity. Gentamicin-induced AKI model in rat was used to examine MDSPCs therapeutic effect. Physiological and histological kidney parameters were determined. MDSPCs exhibited similar immunophenotype, stem cell gene expression, and multilineage differentiation capacities as BM-MSCs, but they demonstrated higher proliferation rate. Single intravenous MDSPCs injection accelerated functional and morphological kidney recovery, as reflected by significantly lower serum creatinine levels, renal injury score, higher urinary creatinine, and GFR levels. PKH-26-labeled MDSPCs were identified within renal cortex 1 and 2 weeks after cell administration, indicating MDSPCs capacity to migrate and populate renal tissue. In conclusion, MDSPCs are capable of mediating functional and histological kidney recovery and can be considered as potential strategy for AKI treatment.

Gentamicin Induced Nephrotoxicity: The Role of Sex Hormones in Gonadectomized Male and Female Rats

Background. Gentamicin (GM) induced nephrotoxicity may be sex hormones related. The effects of sex hormones on GM induced nephrotoxicity in gonadectomized rats were investigated. Methods. Ovariectomized rats received 0.25, 0.5, or 1 mg/kg/week of estradiol (ES) alone or accompanied with 10 mg/kg/week of progesterone (Pro) for two weeks followed by GM (100 mg/kg/day) for 9 days. Castrated rats were also treated with 10, 50, or 100 mg/kg/week of testosterone (TS) for two weeks and then received GM. In addition, a single castrated group received 0.25 mg/kg/week of ES plus GM. Results. GM increased the serum levels of blood urea nitrogen (BUN) and creatinine (Cr) and kidney tissue damage score (KTDS) (P < 0.05). TS had no effect on the serum levels of BUN and Cr and KTDS, while low dose of ES intensified these parameters in male (P < 0.05). ES (0.5 mg/kg) without Pro ameliorated KTDS in female (P < 0.05) while ES (1 mg/kg) with or without Pro exacerbated the BUN values and Cr values, KTDS, and body weight loss (P < 0.05). Conclusion. ES (0.5 mg/kg) without Pro ameliorated kidney damage induced by GM in female while neither TS nor ES had beneficial effect on nephrotoxicity induced by GM in male, although ES aggravated it.

Subacute administration of crude khat (Catha edulis F.) extract induces mild to moderate nephrotoxicity in rats

BACKGROUND

Although various studies have been conducted to shed light on the pharmacological actions of khat, little or no data are available regarding khat's effect on the renal redox system. The aim of this study was therefore to investigate the potential of nephrotoxicity associated with khat exposure in rats.

METHODS

Sprague Dawely rats were randomly assigned into eight experimental groups. Animals were treated with Tween80, gentamicin 100 mg/kg and khat at various doses (100, 200 and 400 mg/kg) alone or in combination with gentamicin for ten days. The animals were then sacrificed to obtain blood and renal tissues for subsequent analysis. Renal markers, including creatinine, blood urea nitrogen, antioxidant enzymes as well as markers for lipid peroxidation were determined using established protocols. In addition, histopathological changes were evaluated with hematoxilin and-eosin staining technique.

RESULTS

Lower and moderate doses of khat did not alter the measured parameters compared to controls. By contrast, higher dose (400 mg/kg) of khat not only increased levels of serum creatinine and blood urea nitrogen (p < 0.001) but also levels of malondialdehyde (p < 0.01). Moreover, 400 mg/kg of khat significantly decreased enzymatic activities of superoxide dismutase (p < 0.01) and catalase (p < 0.001). When khat was administered with gentamicin, it was again the higher dose that significantly accentuated gentamicin-induced alterations in the renal system.

CONCLUSIONS

Khat treatment at high dose is demonstrated to induce mild to moderate renal damage. Moreover, it creates synergy when combined with nephrotoxic drugs such as gentamicin.

Activation of renal haeme oxygenase-1 alleviates gentamicin-induced acute nephrotoxicity in rats

Objectives

This study aimed to investigate whether activation of haeme oxygenase (HO)-1 enzyme by haemin would have beneficial effects on the functional and histological outcome against gentamicin-induced renal damage in rats and sought to elucidate the underlying mechanisms of the therapeutic action.

Methods

Nephrotoxicity was induced by injection of gentamicin (80 mg/kg, i.p.) once daily for seven days. Haemin (50 μmol/kg, i.p.) was given to the control and gentamicin-treated rats in the presence or absence of a HO-1 inhibitor, zinc protoporphyrin IX (ZnPP, 50 μmol/kg per day, i.p.).

Key findings

Haemin treatment prevented gentamicin-induced elevated serum creatinine, urinary protein levels and ameliorated the impaired creatinine clearance. Haemin compensated the deficits in antioxidant enzyme activity and attenuated lipid peroxidation along with decreased reactive oxygen species (ROS) production in renal tissues due to gentamicin. Moreover, haemin pre-administration evoked increased renal HO-1 activity. Additionally, haemin significantly attenuated elevated renal tumour necrosis factor-α (TNF-α), nuclear factor-kappaB (NF-κB) levels and caspase-3 activity alongside ameliorating glomerular pathology. These therapeutic effects were abolished by ZnPP pretreatment.

Conclusions

Here is the first evidence demonstrating the protective effect of HO-1 against gentamicin-associated nephrotoxicity. Suppression of oxidative/inflammatory insults alongside the corresponding decline of apoptosis were presumably responsible for this renoprotection.

Renoprotective effects of the crude extract and solvent fractions of the leaves of Euclea divinorum Hierns against gentamicin-induced nephrotoxicity in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Euclea divinorum Hierns (Ebenaceae) is used in Ethiopian folklore medicine to treat scabies, inflammation of the skin, eczema, abdominal pain, gonorrhea, and kidney problems. However, the claim has not been scientifically validated.

AIM OF THE STUDY

To assess the renoprotective effects of the crude extract and solvent fractions of E. divinorum leaves against gentamicin-induced nephrotoxicity in rats.

MATERIALS AND METHOD

Rats of either sex were divided into seven experimental groups, each comprising six animals. Group I served as control and given vehicle (Tween 80, 2%, v/v in water) and Group II were treated with gentamicin intraperitoneally (100mg/kg/day) for eight days. Group III-V received crude extract at three different doses 100mg/kg, 150mg/kg and 200mg/kg, respectively. Group VI received 100mg/kg of the methanolic fraction and Group VII 100mg/kg of the aqueous fraction. The extract was administered orally two days before and eight days concomitantly with gentamicin. Following treatment, blood and renal tissue were used to assess creatinine, blood urea nitrogen (BUN), malondialdehyde (MDA), antioxidant enzymes and tubular necrosis using recommended procedures. In addition, free radical scavenging activity was determined using in vitro methods.

RESULTS

Gentamicin significantly increased serum creatinine and BUN, MDA and tubular necrosis in rats. It also decreased activity of catalase and superoxide dismutase as well as levels of gluthatione. Pre- and co-treatment with the crude extract and solvent fractions of Euclea divinorum leaves reversed gentamicin-induced alterations as evidenced by a decrease in tubular necrosis, serum and oxidant markers as well as by an increase in antioxidant molecules. Effect was found to decrease with dose when the crude extract was used and maximum protection was conferred by 100mg/kg of the methanolic fraction in both in vivo and in vitro studies.

CONCLUSIONS

Euclea divinorum reversed gentamicin-induced nephrotoxicity, probably via its antioxidant activity. The fact that the methanol fraction conferred maximum protection suggests that semi-polar antioxidant principles might be responsible for the observed effect.

Influence of Spironolactone Treatment on Gentamicin-Induced Nephrotoxicity in Rats

The effect of treatment of rats with gentamicin (80 mg/kg/day for 6 days), oral doses of spironolacatone (20 mg/kg/day for 6 days), and the combined treatment (spironolactone + gentamicin) on renal histology and reduced glutathione (GSH) concentration, and some serum constituents indicative of kidney function were studied. The serum concentrations of creatinine and urea were not significantly affected by spironolactone treatment, but were significantly elevated (P<0.05) by gentamicin administration. The antibiotic treatment also reduced GSH concentration and caused a moderate renal cortical necrosis. However, rats exposed to spironolactone + gentamicin revealed drastic increases in the serum urea and creatinine concentrations amounting to about 1.8 and 2.1 times those of rats treated with gentamicin alone, respectively. The histological examination of slides of the renal cortex of rats exposed to the combined drugs exhibited more extensive necrosis in the tubules when compared to those treated with gentamicin alone. The reduction in GSH induced by gentamicin was unaffected by the concomitant treatment of gentamicin and spironolactone. The concentration of gentamicin accumulated in the renal cortex was significantly larger (twofold) in rats treated concomitantly with spironolactone + gentamicin than in rats treated with gentamicin alone. The present results indicate that spironolactone aggravates gentamicin-induced nephrotoxicity in the rat.

Effect of dimethyl sulfoxide on gentamicin-induced nephrotoxicity in rats

Nephrotoxicity of gentamicin (GM) has been suggested to be mediated by the generation of reduced oxygen metabolites. The present study investigated the possible protective role of the free radical scavenger dimethyl sulfoxide (DMSO) on some indices of GM nephrotoxicity in rats. The antibiotic was injected intramuscularly (i.m.) at a dose of 100 mg/kg for six consecutive days, either with or without treatment with DMSO (12.5%, 25% or 50% in saline) at an intraperitoneal (i.p.) dose of 2 ml/kg 4 days before GM, and concomitantly with GM treatment thereafter. DMSO (25% in saline) was also given as above to rats treated with GM at i.m. doses of 25, 50 or 100 mg/kg for six consecutive days. GM caused dose-dependent significant increases in the concentrations of urea and creatinine in plasma, and in thiobarbituric acid reactive substances (TBARS) level in the kidney cortex and also caused significant decreases in the concentrations of reduced glutathione (GSH) and superoxide dismutase (SOD) activity. In GM-treated rats, DMSO dose-dependently lowered the elevated plasma urea and creatinine concentrations, and the rise in cortical TBARS. It also restored the levels of GSH and SOD activity to near normal. DMSO (25%) was effective in completely preventing the development of signs of nephrotoxicity of G (50 mg/kg). Treatment of the rats with DMSO alone, at any of the above doses, did not alter significantly any of the renal or hepatic function tests studied, and did not appear to adversely affect the kidney or liver histology. However, the efficacy and safety of DMSO require further studies. It is suggested that DMSO has potential protective effect against GM nephrotoxicity in rats.

Magnesium transport in the renal distal convoluted tubule

The distal tubule reabsorbs approximately 10% of the filtered Mg(2+), but this is 70-80% of that delivered from the loop of Henle. Because there is little Mg(2+) reabsorption beyond the distal tubule, this segment plays an important role in determining the final urinary excretion. The distal convoluted segment (DCT) is characterized by a negative luminal voltage and high intercellular resistance so that Mg(2+) reabsorption is transcellular and active. This review discusses recent evidence for selective and sensitive control of Mg(2+) transport in the DCT and emphasizes the importance of this control in normal and abnormal renal Mg(2+) conservation. Normally, Mg(2+) absorption is load dependent in the distal tubule, whether delivery is altered by increasing luminal Mg(2+) concentration or increasing the flow rate into the DCT. With the use of microfluorescent studies with an established mouse distal convoluted tubule (MDCT) cell line, it was shown that Mg(2+) uptake was concentration and voltage dependent. Peptide hormones such as parathyroid hormone, calcitonin, glucagon, and arginine vasopressin enhance Mg(2+) absorption in the distal tubule and stimulate Mg(2+) uptake into MDCT cells. Prostaglandin E(2) and isoproterenol increase Mg(2+) entry into MDCT cells. The current evidence indicates that cAMP-dependent protein kinase A, phospholipase C, and protein kinase C signaling pathways are involved in these responses. Steroid hormones have significant effects on distal Mg(2+) transport. Aldosterone does not alter basal Mg(2+) uptake but potentiates hormone-stimulated Mg(2+) entry in MDCT cells by increasing hormone-mediated cAMP formation. 1,25-Dihydroxyvitamin D(3), on the other hand, stimulates basal Mg(2+) uptake. Elevation of plasma Mg(2+) or Ca(2+) inhibits hormone-stimulated cAMP accumulation and Mg(2+) uptake in MDCT cells through activation of extracellular Ca(2+)/Mg(2+)-sensing mechanisms. Mg(2+) restriction selectively increases Mg(2+) uptake with no effect on Ca(2+) absorption. This intrinsic cellular adaptation provides the sensitive and selective control of distal Mg(2+) transport. The distally acting diuretics amiloride and chlorothiazide stimulate Mg(2+) uptake in MDCT cells acting through changes in membrane voltage. A number of familial and acquired disorders have been described that emphasize the diversity of cellular controls affecting renal Mg(2+) balance. Although it is clear that many influences affect Mg(2+) transport within the DCT, the transport processes have not been identified.

Aminoglycosides inhibit hormone-stimulated Mg2+uptake in mouse distal convoluted tubule cells

The clinical use of aminoglycosides often leads to renal magnesium wasting and hypomagnesemia. Of the nephron segments, both the thick ascending limb of Henle's loop and the distal tubule play significant roles in renal magnesium conservation but the distal convoluted tubule exerts the final control of urinary excretion. An immortalized mouse distal convoluted tubule (MDCT) cell line has been extensively used to study the cellular mechanisms of magnesium transport in this nephron segment. Peptide hormones, such as parathyroid hormone (PTH), glucagon, calcitonin, and arginine vasopressin (AVP) stimulate Mg2+uptake in MDCT cells that is modulated by extracellular polyvalent cations, Ca2+and Mg2+. The present studies determined the effect of aminoglycosides on parathyroid hormone (PTH)-mediated cAMP formation and Mg2+uptake in MDCT cells. Gentamicin, a prototypic aminoglycoside, illicited transient increases in intracellular Ca2+from basal levels of 102 ± 13 nM to 713 ± 125 nM, suggesting a receptor-mediated response. In order to determine Mg2+transport, MDCT cells were Mg2+-depleted by culturing in Mg2+-free media for 16 h and Mg2+uptake was measured by microfluorescence after placing the depleted cells in 1.0 mM MgCl2. The mean rate of Mg2+uptake, d([Mg2+]i)/dt, was 138 ± 24 nM/s in control MDCT cells. Gentamicin (50 µM) did not affect basal Mg2+uptake (105 ± 29 nM/s), but inhibited PTH stimulated Mg2+entry, decreasing it from 257 ± 36 nM/s to 108 ± 42 nM/s. This was associated with diminished PTH-stimulated cAMP formation, from 80 ± 2.5 to 23 ± 1 pmol/mg protein·5 min. Other aminoglycosides such as tobramycin, streptomycin, and neomycin also inhibited PTH-stimulated Mg2+entry and cAMP formation. As these antibiotics are positively charged, the data suggest that aminoglycosides act through an extracellular polyvalent cation-sensing receptor present in distal convoluted tubule cells. We infer from these studies that aminoglycosides inhibit hormone-stimulated Mg2+absorption in the distal convoluted tubule that may contribute to the renal magnesium wasting frequently observed with the clinical use of these antibiotics.Key words: intracellular Mg2+, Mg2+uptake, aminoglycosides, gentamicin, tobramycin, streptomycin, neomycin, parathyroid hormone, microfluorescence, cAMP measurements.

The protective effect of taurine against gentamicin-induced acute tubular necrosis in rats

BACKGROUND

Taurine, which is the major intracellular free beta-amino acid, is known to be an endogenous antioxidant and a membrane-stabilizing agent. In this study, we wished to know whether taurine altered the concentration of gentamicin in kidney tissue and could protect against gentamicin-induced acute proximal tubular injury.

METHODS

Wistar albino rats of both sexes were assigned to three groups, which all received one of the following daily intraperitoneal injections for 8 days: (i) 0.9% sodium chloride (NaCl) alone at the same volume as gentamicin treated rats (group C; n=8); (ii) 100 mg/kg/day gentamicin alone (group G; n=8, four male, four female); or (iii) 100 mg/kg/day gentamicin plus 7.5 ml/kg/day taurine (group G+T; n=9, five male, four female). Urine was collected for 24 h for the determination of urine volume and creatinine. Intracardiac blood was collected for blood urea nitrogen (BUN) and serum creatinine determination. The kidneys were removed, weighed, and the left kidneys were subjected to biochemical analysis for the determination of thiobarbituric acid-reactive substance (TBARS) and lactate levels, and glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities. The right kidneys were divided vertically in half. The upper halves were used for histopathological examination, by light and electron microscopy. The lower halves were used to detect the gentamicin concentration within the kidney tissue, by high-performance liquid chromatography (HPLC). Changes in body weight and normalized kidney weight were recorded.

RESULTS

Taurine treatment reduced gentamicin-induced increases in serum creatinine, 24 h urine volume, BUN and tissue lactate and TBARS levels (0.57+/-0.02 vs 1.06+/-0.08 mg/dl, P<0.001; 9.00+/-1.46 vs 20.9+/-2.73 ml, P<0.001; 25.3+/-1.87 vs 54.1+/-6.99 mg/dl, P<0. 001; 2.56+/-0.10 vs 3.44+/-0.08 micromol/g wet tissue, P<0.001; and 66.4+/-3.41 vs 79.5+/-5.07 nmol/g wet tissue, P>0.05, respectively). Taurine reduced the accumulation of gentamicin within the kidney tissue (233+/-29 vs 494+/-93 microg/g wet tissue, P<0.05). Taurine treatment also prevented body weight loss due to gentamicin administration (17.8+/-1.64 vs -10.0+/-7.08 g, P<0.01) and normalized reduced Gpx and SOD activities (3.46+/-0.16 vs 2.37+/-0. 15 U/g wet tissue, P<0.01; and 15577+/-377 vs 12662+/-577 U/g wet tissue, P<0.01, respectively). Light microscopic examination of the renal tissues from gentamicin-treated rats revealed severe histopathological changes, whereas specimens obtained from taurine-treated rats revealed only mild changes. This finding was supported by electron microscopic examination.

CONCLUSIONS

Our observations suggest that taurine treatment attenuates the accumulation of gentamicin within kidney tissue and counteracts the deleterious effect of gentamicin on renal tubular function. They may have potentially important clinical implications.

Carvedilol: a beta blocker with antioxidant property protects against gentamicin-induced nephrotoxicity in rats

Gentamicin is an antibiotic effective against gram negative infections, whose clinical use is limited by its nephrotoxicity. Since the pathogenesis of gentamicin-induced nephrotoxicity involves oxygen free radicals, the antioxidant carvedilol may protect against gentamicin-induced renal toxicity. We therefore tested this hypothesis using a rat model of gentamicin nephrotoxicity. Carvedilol (2 mg/kg) was administered intraperitoneally 3 days before and 8 days concurrently with gentamicin (80 mg/kg BW). Estimations of urine creatinine, glucose, blood urea, serum creatinine, plasma and kidney tissue malondialdehyde (MDA) were carried out, after the last dose of gentamicin. Kidneys were also examined for morphological changes. Gentamicin caused marked nephrotoxicity as evidenced by increase in blood urea, serum creatinine and decreased in creatinine clearance. Blood urea and serum creatinine was increased by 883% and 480% respectively with gentamicin compared to control. Carvedilol protected the rats from gentamicin induced nephrotoxicity. Rise in blood urea, serum creatinine and decrease in creatinine clearance was significantly prevented by carvedilol. There was 190% and 377% rise in plasma and kidney tissue MDA with gentamicin. Carvedilol prevented the gentamicin induced rise in both plasma and kidney tissue MDA. Kidney from gentamicin treated rats, histologically showed necrosis and desquamation of tubular epithelial cells in renal cortex, whereas it was very much comparable to control with carvedilol. In conclusion, carvedilol with its antioxidant property protected the rats from gentamicin-induced nephrotoxicity.

Effect of superoxide dismutase treatment on gentamicin nephrotoxicity in rats

The effect of administration of superoxide dismutase (SOD) on gentamicin nephrotoxicity was examined in rats. SOD was administered at a dose of 2000 i.u/kg or 8000 i.u/kg for 10 consecutive days, and nephrotoxicity was induced by daily i.m. injections of gentamicin at a dose of 80 mg/kg during the last 6 days of the experimental period. Gentamicin induced significant increases in plasma creatinine and urea and protein urinary concentrations, and significant decreases in creatinine clearance and kidney cortical alkaline phosphatase activity and reduced glutathione (GSH) concentrations. The antibiotic also produced marked necrosis of the renal proximal tubules. SOD treatment (8000 i.u/kg) reversed most of these variables, indicating that it was effective in ameliorating gentamicin nephrotoxicity. However, at a dose of 2000 i.u./kg it was mostly ineffective.

Gentamicin nephrotoxicity in humans and animals: some recent research

It would appear from the literature cited in this article, that interest in gentamicin nephrotoxicity is still thriving. Despite extensive studies, the mechanism(s) of the nephrotoxicity is uncertain. Several clinical and experimental strategies have been employed in order to ameliorate or abolish the signs of gentamicin nephrotoxicity. Most of these were unsuccessful, impractical or unsafe. Therefore there is still a need for further studies to elucidate the mechanism(s) of action of the drugs nephrotoxicity, and to discover safe, practical and effective agents to ameliorate the nephrotoxicity in patients at risk.

The effect of thyroxine or carbimazole treatment on gentamicin nephrotoxicity in rats

1. This study examines the effect of treating rats with gentamicin (80 mg kg-1 day-1 intramuscularly (i.m.), for 6 days) alone or with either L-thyroxine or the anti-thyroid drug carbimazole. 2. Gentamicin produced significant increases in serum creatinine and urea concentrations, and significantly reduced the activity of Na+,K+ATPase in renal cortex. The concentration of serum triiodothyronine (T3) was unaffected by graded doses (20, 40 and 80 mg kg-1) of the antibiotic. Histopathologically, gentamicin produced necrosis of proximal tubules in the renal cortical tissues of treated rats. 3. Treatment of rats with either L-thyroxine or carbimazole alone did not significantly affect any of the biochemical variables investigated. Carbimazole alone produced only mild tubular necrosis. 4. Treatment of rats with either L-thyroxine (100 micrograms kg-1 day-1, subcutaneously) for 10 days, and gentamicin (80 mg kg-1, i.m. daily during the last 6 days of treatment significantly reduced the gentamicin-induced increases in serum creatinine and urea concentrations, and increased the activity of cortical N+,K+ATPase to control levels. Histopathologically, the severity of gentamicin-induced tubular necrosis was reduced by L-thyroxine treatment. 5. Carbimazole (12 mg ml-1 in drinking water for 21 days) and gentamicin (80 mg kg-1 i.m.) daily during the last 6 days of treatment, stimulated the increase in serum urea concentration produced by gentamicin, but did not significantly affect the gentamicin-induced changes in serum creatinine or cortical N+,K+ATPase.

Magnesium deficiency: pathophysiologic and clinical overview

Magnesium is an essential cation, involved in many enzymatic reactions, as a cofactor to adenosine triphosphatases. It is critical in energy-requiring metabolic processes, as well as protein synthesis and anaerobic phosphorylation. Serum Mg concentration is maintained within a narrow range by the kidney and small intestine since under conditions of Mg deprivation both organs increase their fractional absorption of Mg. If Mg depletion continues, the bone store contributes by exchanging part of its content with extracellular fluid (ECF). The serum Mg can be normal in the presence of intracellular Mg depletion, and the occurrence of a low level usually indicates significant Mg deficiency. Hypomagnesemia is frequently encountered in hospitalized patients and is seen most often in patients admitted to intensive care units. The detection of Mg deficiency can be increased by measuring Mg concentration in the urine or using the parenteral Mg load test. Hypomagnesemia may arise from various disorders of the gastrointestinal tract, conditions affecting Mg renal handling, or cellular redistribution of Mg. The gastrointestinal causes include the following: protein-calorie malnutrition, the intravenous administration of Mg-free fluids and total parenteral nutrition, chronic watery diarrhea and steatorrhea, short bowel syndrome, bowel fistula, continuous nasogastric suctioning, and, rarely, primary familial Mg malabsorption. The renal causes include Bartter's and Gitelman's syndrome, post obstructive diuresis, post acute tubular necrosis, renal transplantation, and interstitial nephropathy. Many therapeutic agents cause renal Mg wasting and subsequent deficiency. These include loop and thiazide diuretics, aminoglycosides, cisplatin, pentamidine, and foscarnet. Magnesium deficiency is seen frequently in alcoholics and diabetic patients, in whom a combination of factors contributes to its pathogenesis. Hypomagnesemia is known to produce a wide variety of clinical presentations, including neuromuscular irritability, cardiac arrhythmias, and increased sensitivity to digoxin. Refractory hypokalemia and hypocalcemia can be caused by concomitant hypomagnesemia and can be corrected with Mg therapy. The dose and route of administration of Mg in the treatment of hypomagnesemia is dictated by the clinical presentation, the degree of Mg deficiency, and the renal function.

Effect of gentamicin-induced nephrotoxicity on some carbohydrate metabolic pathways in the rat renal cortex

Rats were injected with gentamicin at doses of 20, 40 and 80 mg/kg per day for 6 consecutive days. The treatment caused nephrotoxicity as evidenced by dose-related increases in serum creatinine concentration and renal tubular necrosis. The nephrotoxicity was accompanied by reduced renal cortical and fasting blood glucose levels, and by increases in serum lactate concentrations. The activities of cortical malate dehydrogenase and alanine transaminase were significantly reduced by the three doses of gentamicin. On the other hand, aspartate transaminase activity was lowered only by the highest dose of antibiotic used. However, the activity of cortical glucose-6-phosphate dehydrogenase was altered by the 20 and 40 mg/kg doses of gentamicin, but not by the 80 mg/kg dose. The two lower doses reduced the lactate content of the cortex but activated lactate dehydrogenase. The activity of isocitrate dehydrogenase was not altered by any of the gentamicin doses used.

Influence of iron, deferoxamine and ascorbic acid on gentamicin-induced nephrotoxicity in rats

1. Nephrotoxicity was induced in rats by injecting gentamicin intramuscularly (i.m.) at a dose of 80 mg/kg for 6 days. Treated animals demonstrated a typical pattern of nephrotoxicity characterized by increased serum creatinine and urea concentrations, and by necrosis of proximal tubular epithelium. 2. Pretreatment of rats with iron (Fe3+) at daily i.m. doses of 2, 4 and 8 mg/kg for 14 days, with gentamicin given during the last 6 days of treatment, significantly potentiated the gentamicin-induced increases in creatinine and urea concentrations and exacerbated renal histological damage. 3. Gentamicin significantly increased serum Fe3+ concentration in rats treated with Fe3+ and gentamicin, compared to Fe(3+)-treated rats. 4. The Fe3+ antidote deferoxamine (100 mg/kg, i.m.) given with gentamicin was ineffective in antagonizing the potentiating effect of Fe3+ on gentamicin-induced nephrotoxicity. 5. Ascorbic acid (50 mg/kg, i.m. for 14 days) was ineffective in altering the nephrotoxicity of gentamicin (80 mg/kg) given during the last 6 days of treatment. At a dose of 100 mg/kg for 14 days, ascorbic acid significantly reduced gentamicin-induced increases in creatinine and urea levels, and ameliorated proximal tubular damage. However, at a dose of 200 mg/kg, ascorbic acid exacerbated gentamicin-induced increases in creatinine and urea levels and increased the severity of the histological damage.

Comparative modulating effects of captopril, diltiazem, dietary calcium and pyridoxal-5'-phosphate on gentamicin-induced nephrotoxicity in the rat

1. Nephrotoxicity was induced in rats by injecting gentamicin intramuscularly (i.m.) at a dose of 80 mg/kg/day for 6 days. Treated animals demonstrated a typical pattern of aminoglycoside nephrotoxicity characterized histopathologically by necrosis of proximal tubular epithelium, and biochemically by increased serum creatinine and urea concentrations. Reduced glutathione (GSH) concentration in renal cortex was significantly decreased by gentamicin. 2. Simultaneous treatment of rats with gentamicin and either captopril or diltiazem significantly potentiated the gentamicin-induced increases in serum creatinine and urea and did not significantly affect the gentamicin-induced decrease in cortical GSH concentration. 3. Concomitant treatment with gentamicin and either Ca2+ or pyridoxal-5'-phosphate decreased serum urea level, did not significantly affect serum creatinine concentration, and significantly increased cortical GSH concentration in comparison to the values of these parameters following gentamicin treatment. 4. Histopathologically, the severity of gentamicin-induced renal damage was exacerbated by captopril, and even more so by diltiazem. Simultaneous treatment with gentamicin and either Ca2+ or pyridoxal-5'-phosphate produced only mild focal atrophy of renal tubular epithelium. Control rats had apparently normal histology. 5. In conclusion, captopril and diltiazem, at the doses used, significantly potentiated gentamicin-induced nephrotoxicity to a broadly similar extent. Although Ca2+ and pyridoxal-5'-phosphate, at the doses used, reduced significantly the severity of some of the manifestations of nephrotoxicity, they were equally ineffective in completely preventing the development of nephrotoxicity.