Effect of cyclosporine A on accumulation of tetraethylammonium and p-aminohippurate, and on lipid peroxidation in rat renal microsomes and cortical slices

The effect of cyclosporine A (CsA) on lipid peroxidation (LPO) was assessed in renal cortical slices and renal microsomes. Cortical slices were incubated with 1500 micrograms/ml CsA and microsomes with 0.5-20 micrograms/ml under identical conditions (pH 7.4, 37 degrees C) for 3 hours, and LPO monitored by the formation of malondialdehyde (MDA). CsA at concentrations of 3 micrograms/ml and higher caused a significant increase MDA in microsomes and renal cortical slices showed a time dependent release of MDA into the incubation medium. The influence of CsA on tetraethammonium (TEA) and p-aminohippurate (PAH) accumulation in renal cortical slices was investigated for up to 3 hours with concentration of CsA from 10 to 1000 micrograms/ml. CsA caused a time- and concentration-dependent decrease of TEA accumulation and higher concentrations of CsA decreased PAH accumulation in renal cortical slices. The results add further evidence to the suggestion that lipid peroxidation participate in CsA-induced impairment of kidney function.     

Amphotericin B and sodium deoxycholate induced impairment of renal p-aminohippurate accumulation (PAH) and effect on lipid peroxidation in the rat kidney.

The influence of amphotericin B on PAH transport as well as on lipid peroxidation in rat renal cortical slices was studied in vitro and ex vivo. In vitro, renal cortical slices were incubated with different amphotericin B (AmB) concentrations (2-60 micrograms/mL) or with the corresponding vehicle concentrations of sodium deoxycholate (NaDo) (1.64-49.2 micrograms/mL) and time dependently (15-30-60 min) with 30 micrograms/mL AmB or 24.6 micrograms/mL NaDo. Ex vivo, PAH transport of renal cortical slices was investigated following a 3-day intravenous AmB administration with 3 mg/kg per day or 2.46 mg/kg/day NaDo, respectively. In vitro AmB as well as NaDo decreased PAH transport dose and time dependently. At the highest AmB concentration of 60 micrograms/mL, PAH uptake decreased to 17.6%. The corresponding NaDo concentration (49.2 micrograms/mL) decreased PAH uptake to 33.3%. Time dependently AmB decreased PAH uptake to 25% after 60 min. NaDo caused a decrease to 69%. Administration of AmB for 3 days resulted in a PAH decline to 81%; NaDO decreased PAH uptake to 77%. In vitro as well as in vivo, AmB or its vehicle did not induce lipid peroxidation in renal cortical tissue. In summary, the results show that AmB and its vehicle, NaDo, decrease PAH uptake by renal cortical cells, reflecting a direct effect of AmB on tubular function. The impairment of the PAH transport is not due to enhanced lipid peroxidation.     

Evidence that alterations in renal metabolism and lipid peroxidation may contribute to cyclosporine nephrotoxicity

This study was designed to investigate aspects of renal xenobiotic metabolism and the renal cellular response to drug-induced injury, in mediating cyclosporine nephrotoxicity. The relation between CsA and renal enzyme activity has not previously been investigated. In this study, CsA induced alterations in rat renal cortical microsomal NADPH cytochrome P-450 reductase activity, microsomal and mitochondrial lipid peroxidation, and renal cortical glutathione levels were investigated. CsA, in vivo (50 mg/kg/day for 4 days), increased in vitro lipid peroxidation in microsomes and mitochondria. CsA produced a significant uncompetitive inhibition of renal NADPH cytochrome P-450 reductase activity. The low activity and maximal enzyme velocity (Vmax) suggest that the amount of renal enzyme available for metabolism may be a rate-limiting step and could contribute to the development of toxicity. CsA in vivo reduced the renal cortical glutathione ratio (GSH/GSSG), which may also reduce the renal cellular response to CsA injury. This study has demonstrated that CsA nephrotoxicity may, in part, be mediated by CsA-induced alterations in renal xenobiotic metabolism.     

Salviae radix extract prevents cisplatin-induced acute renal failure in rabbits.

The present study was carried out to determine if salviae radix extract (SRE) exerts a beneficial effect against cisplatin-induced renal failure in rabbits. Rabbits were pretreated with SRE orally for 7 days, followed by cisplatin injection (5 mg/kg i.p.). Cisplatin injection caused a reduction in GFR, which was accompanied by an increase in serum creatinine levels. The fractional Na+ excretion was increased by cisplatin injection. PAH uptake by renal cortical slices was inhibited by the administration of cisplatin. Such changes were prevented by SRE pretreatment. Cisplatin injection increased lipid peroxidation, which was prevented by SRE pretreatment. The protective effect of SRE was supported by morphological studies. Cisplatin injection reduced renal blood flow that was not affected by SRE pretreatment. Cisplatin treatment in vitro in renal cortical slices increased LDH release and lipid peroxidation, which were prevented by 0.05% SRE. These results indicate that lipid peroxidation plays a critical role in cisplatin-induced acute renal failure. SRE exerts a protective effect against renal cell injury induced by cisplatin, and its effect may be attributed to its antioxidant action. However, the underlying mechanism by which SRE has antioxidant action remains to be defined.     

Elevated serum concentration of cardiotoxic lipid peroxidation products in chronic renal failure in relation to severity of renal anemia

Patients with end-stage renal disease undergoing hemodialysis (HD) are exposed to oxidative stress. Increased levels of malondialdehyde (MDA) and 4-hydroxylnonenal (HNE) were found in plasma of uremic patients indicating accelerated lipid peroxidation (LPO) as a consequence of multiple pathogenetic factors. The catabolism and action of those products was already intensively studied. As highly reactive metabolites they are able to bind to proteins, nucleic acids, and other molecules. Doing so, they exert molecular signal effects in cells and are able to exacerbate tissue and organ damage, e.g. cardiotoxic effects. Since renal anemia was shown to promote oxidative stress as well, the aim of our investigation was to examine its role in HD patients. Therefore, two groups of HD patients were investigated (group I Hb < 10 g/dl, group II Hb > 10 g/dl) and serum concentrations of MDA, HNE, and of protein carbonyls, a marker for protein oxidation, were determined. All HD patients had significantly higher levels of the LPO products MDA and HNE compared with controls. However, group I patients showed higher MDA and HNE concentrations compared to group II patients. The same result could be seen for protein carbonyls. During HD concentration of both LPO products decreased. However, this was not the case for protein carbonyls. These results lead to the conclusion that optimized correction of the renal anemia may result in a significant reduction of oxidative stress and therefore in the reduction of organ tissue damage. In this way correction of renal anemia will reduce the cardiovascular risk and comorbidity of HD patients improving their prognosis.     

Ex vivo stimulation of renal transport of the cytostatic drugs methotrexate,cisplatin, topotecan (Hycamtin) and raltitrexed (Tomudex) by dexamethasone,T3 and EGF in intact human and rat kidney tissue and in human renal cell carcinoma

Previous experiments have shown that both in vivo and in vitro pre-treatment with various hormones increases the renal transport capacity for weak organic acids, such as PAH, in rats. The aim of the present study was to test whether or not accumulation of the anticancer drugs methotrexate (MTX), cisplatin (CP), raltitrexed (Tomudex) and topotecan (Hycamtin) can be increased in intact, healthy rat and human renal cortical slices and in human renal cell carcinoma (RCC). Intact, healthy human tissue was obtained from tumour bearing kidneys of patients suffering from RCC. Experiments were intended as a new approach to overcome so-called multidrug resistance. Kidney tissue slices were incubated for 24 h in William's medium E containing various concentrations of dexamethasone, T(3), or EGF. Thereafter slices were placed in anticancer drug containing Cross-Taggart medium and the drug uptake into kidney tissue was measured for 2 h. In intact rat and human renal tissue slices, the uptake of p-aminohippurate (PAH = reference substance) increased significantly after incubation in dexamethasone containing medium (134% and 156%, respectively). There were no stimulating effects of either T(3) or EGF on PAH accumulation. On the other hand, only the accumulation of MTX, but not of CP, raltitrexed or topotecan, was significantly enhanced after hormone pre-treatment both in intact renal tissue and in RCC. A stimulation of renal PAH accumulation can be performed ex vivo, as reported previously, both in intact rat and human renal cortical slices and in RCC. Discrepancies between the effects of dexamethasone and T(3) or EGF indicate different modes of action of these substances at the cellular level. Unfortunately, with the exception of MTX, the uptake of anticancer drugs can not be stimulated effectively ex vivo in human RCC tissue by the substances used. Evidently the transport of these anticancer drugs out of the kidney cells is more effective than their uptake.     

In vitro stimulation of renal tubular p-aminohippurate transport by dexamethasone in rat kidneys and in intact kidney tissue of patients suffering from renal cell carcinoma

The aim of this study was to test whether or not the accumulation of p-aminohippurate (PAH) can be increased in intact human renal cortical slices obtained from tumor-bearing kidneys of patients suffering from renal cell carcinoma (RCC). Tissue slices were incubated for 24 h in Williams medium E containing 0.01–50 μM dexamethasone. Thereafter slices were placed in PAH-containing Cross-Taggart medium and PAH uptake into kidney tissue was measured for 2 h. In both rat and human renal tissue slices, PAH uptake capacity increased significantly in a concentration-dependent manner after 24 h of incubation in dexamethasone-containing medium (rat, 136%; man, 156%). The stimulatory effect was already significant after 12 h of incubation. In additional experiments it was shown that incubation in triiodothyronine (T₃)-containing medium has different effects: in man, T₃ does not influence the PAH accumulation capacity of renal cortical slices whereas in rats PAH accumulation is significantly lower after 24 h of incubation with T₃. Thus stimulation of tubular transport capacity can be performed in vitro in human renal cortical slices. Discrepancies between the effects of dexamethasone and T₃ indicate different modes of action of the two hormones at the cellular level. Received: 4 August 1997 / Accepted: 28 October 1997     

Secondary venous ischemic injury associated with neutrophil infiltration and lipid peroxidation: amelioration of injury by cyclosporin A in a rat inguinal island flap

Secondary venous ischemia caused by anastomotic failure is one of the major causes of failure after free tissue transfers and replantations. The effects of cyclosporin A (CsA) on secondary ischemic injury associated with neutrophil infiltration and lipid peroxidation were evaluated in a rat inferior epigastric island skin flap model. Primary ischemia was produced by arteriovenous occlusion for 2 hours. Twenty-four hours later, secondary venous ischemia was produced by 5 hours of venous occlusion. Nonischemic (n = 5), primary ischemic (n = 5), and secondary ischemic control groups (n = 10), and four treatment groups (n = 10) were created. Treatment groups received either 15 or 30 mg per kilogram per day oral CsA for 3 days before flap elevation, or 15 or 30 mg per kilogram intravenous CsA at 4 hours of secondary venous ischemia. Flap survival area, malondialdehyde (MDA) content, and myeloperoxidase (MPO) activity were assayed for each group. The mean flap survival area of the high-dose posttreatment group was significantly higher than the secondary ischemic control group (29% +/- 39% vs. 3% +/- 8%; p < 0.05, Student's t-test). The MDA and MPO levels of each treatment group were significantly lower than the secondary ischemic control group at hours 1 and 24 (p < 0.0001, Student's t-test). The lowest MDA and MPO levels were achieved in the high-dose posttreatment group. Results suggest that CsA may improve flap survival after secondary venous ischemia by attenuating neutrophil infiltration and by reducing lipid peroxidation.     

Hormonal control of postnatal development of renal tubular transport of weak organic acids

We have postulated that the maturation of the renal transport mechanism for weak organic acids is controlled by thyroid and adrenal hormones. Administration of T₃ and T₄ (20 g/100 g body wt. for 3 days) to immature rats enhanced by 50% the accumulation of p-aminohippurate (PAH) in renal cortical slices of 5- to 30-day-old rats. The effect of T₃ was lower, while T₄ had no effect, in 50- and 105-day-old animals. Enhancement of PAH transport became apparent 24 h and disappeared by 9 days after the end of hormone treatment. Administration of a booster dose of T₃ (1 g/100 g body wt.) on day 9 brought the level of PAH accumulation to values similar to those observed 24 h after the end of the initial 3 days of T₃ administration. Dexamethasone administration (80 mg/100 g body wt. for 3 days) affected PAH uptake only in cortical slices obtained from 5-day-old rats. Changes in PAH accumulation did not correlate with changes in kidney weight or protein synthesis, indicating that they were mediated by the hormones rather than being consquent to growth.     

Does long-term treatment of renal anaemia with recombinant erythropoietin influence oxidative stress in haemodialysed patients?

Background. Patients with end-stage renal failure undergoing haemodialysis (HD) are exposed to oxidative stress. Increased levels of malondialdehyde (MDA) were demonstrated in plasma of uraemic patients, indicating accelerated lipid peroxidation (LPO) as a consequence of multiple pathogenetic factors. The aim of our investigation was to examine the role of renal anaemia in oxidative stress in HD patients. Methods. MDA and 4-hydroxynonenal (HNE) were measured in three groups of patients undergoing HD: group I comprised eight patients with a blood haemoglobin (Hb) <10 g/dl (mean Hb=8.1±1.3 g/dl), and group II were eight patients with a Hb <10 g/dl (mean Hb=12.4±1.9 g/dl); none of these 16 patients had been treated with human recombinant erythropoietin (rHuEpo). Group III comprised 27 patients with a mean Hb of 10.5±1.6 g/dl after long-term rHuEpo treatment. Results. Mean plasma concentrations of both MDA and HNE were significantly higher (P<0.0001) in all 43 HD patients than in 20 healthy controls (MDA 2.85±0.25 vs 0.37± &mgr;M, HNE 0.32± vs 0.10±0.01 &mgr;M). Comprising the three groups, it was shown that HD patients with a Hb <10 g/dl had significantly higher plasma levels of LPO products (MDA 3.81±0.86 &mgr;M, HNE 0.45±0.07 &mgr;M) than HD patients with a Hb > 10 g/dl (MDA 2.77±0.58 &mgr;M, HNE 0.25±0.05 &mgr;M), and than HD patients treated with rHuEpo (MDA 2.50±0.12 &mgr;M, HNE 0.29±0.03 &mgr;M). Furthermore, an inverse correlation between plasma concentration of LPO products and haemoglobin levels was seen (r=0.62, P<0.0001). Conclusion. Radical generation in HD patients might be caused in part by renal anemia itself. Treatment with rHuEpo may decrease radical generation effectively in HD patients due to the increase in the number of red blood cells and blood haemoglobin concentration. Keywords: erythropoietin; haemodialysis; HNE; lipid peroxidation; MDA; renal anaemia      

Oxidative stress in renal anemia of hemodialysis patients is mitigated by epoetin treatment

BACKGROUND/AIMS: Oxidative stress often occurs in chronic hemodialysis (HD) patients. The objective of our study was to investigate the interrelationship between oxidative stress and the degree of renal anemia. METHODS: In 107 consecutive HD patients, serum concentrations of two major aldehydic lipid peroxidation (LPO) products, 4-hydroxynonenal (HNE) and malondialdehyde (MDA), and of protein carbonyls were analyzed as parameters of oxidative stress and related to the degree of renal anemia. Additionally, in 76 patients treated with epoetin long-term changes in the serum levels of aldehydic LPO products were observed. RESULTS: In HD patients, serum levels of HNE, MDA, and protein carbonyls are increased in comparison to controls. The lower the hemoglobin, i.e. the stronger the degree of renal anemia, the higher the serum concentrations of HNE, MDA, and protein carbonyls. The HNE and MDA levels decreased during HD. Long-term studies on the correction of renal anemia by epoetin demonstrated a mitigation of oxidative stress during this therapy. During periods of 1 and 2 years, it was observed that the serum levels of HNE and MDA could be reduced. CONCLUSION: Chronic renal failure is connected with oxidative stress which correlates with the degree of renal anemia, and the serum levels of aldehydic LPO products could be reduced during correction of renal anemia by epoetin.     

Differential role of reactive oxygen species in chemical hypoxia-induced cell injury in opossum kidney cells and rabbit renal cortical slices

This study was undertaken to evaluate the role of reactive oxygen species (ROS) and lipid peroxidation in chemical hypoxia in opossum kidney (OK) cells and rabbit renal cortical slices. Chemical hypoxia was induced by incubating cells or slices with antimycin A, an inhibitor of mitochondrial electron transport. Exposure of OK cells to chemical hypoxia resulted in a time-dependent cell death and parallel depletion of intracellular ATP. In OK cells subjected to chemical hypoxia, the generation of ROS was increased, and this was prevented by the H(2)O(2) scavenger catalase, but not by the hydroxyl radical scavenger dimethylthiourea (DMTU). Catalase prevented OK cell death induced by chemical hypoxia, but [Cu, Zn]-superoxide dismutase (SOD) and DMTU were not effective. The iron chelators deferoxamine and phenanthroline prevented chemical hypoxia-induced OK cell death, but the potent antioxidants N,N'-diphenyl-p-phenylenediamine (DPPD) and butylated hydroxyanisole (BHA) showed no beneficial effect. Antimycin A in OK cells increased lipid peroxidation, which was prevented by DPPD and phenanthroline. In rabbit renal cortical slices, antimycin A caused an increase in LDH release and lipid peroxidation, and these effects were prevented by ROS scavengers (SOD, catalase, and DMTU), iron chelator (deferoxamine), and antioxidants (DPPD and BHA). However, in primary cultured rabbit proximal tubular cells the antimycin A-induced cell death was not altered by antioxidants. The extent of ATP depletion was similar in renal cortical slices and primary cultured cells treated with antimycin A. These results indicate that chemical hypoxia-induced cell injury is not directly resulted from lipid peroxidation in OK cells, but this cell injury is mediated by lipid peroxidation in rabbit renal cortical slices. This discrepancy may be due to the difference in cell preparation (freshly prepared tubules and cultured cells).     

Correlation of renal organic anion and cation transport with blood pressure in SHR.

In 1974, we found that sera from SHR suppressed renal PAH transport (PSEBM 145:97, 1974). Since a "natriuretic factor" depresses PAH as well as Na transport, we proposed that "natriuretic factor" was elevated in SHR. Our current investigation amplifies the previous study. On a given day, one spontaneously hypertensive rat (SHR) and one rat from a normotensive strain [Wistar Kyoto (WKY) or Sprague-Dawley (SD]) were examined together. SHR sera compared to WKY/SD sera significantly depress PAH (organic anion) and TEA (organic cation) uptake by rat renal slices. The ability of SHR sera to depress uptake correlated significantly with the BP: the sera with the greatest depressive influence on renal PAH and TEA uptake came from the SHR with the highest BP (PAH r = 0.89, p less than 0.0001; TEA = r = 0.76, p less than 0.01). Subsequent separation of serum on Sephadex 25 localized the factor to the same fraction as "natriuretic hormone". A similar correlation was found between the ability of the fraction to depress the 2 transports and the height of the BP. The serum factor did not inhibit ATPase activity. In contrast to the serum effects, renal slices removed from SHR showed increased rather than decreased PAH and TEA transport which significantly correlated with the BP. The slices with the highest uptakes came from the SHR with the highest BP. The high uptake of organic ions by the SHR renal slices could be an adaptive response to the serum factor or vice versa. We postulate that a serum factor which depresses PAH and TEA transport and is not "ouabain-like" may play a role in the BP elevation of SHR.     

Halothane-dependent lipid peroxidation in human liver microsomes is catalyzed by cytochrome P4502A6 (CYP2A6)

BACKGROUND: Halothane is extensively (approximately 50%) metabolized in humans and undergoes both oxidative and reductive cytochrome P450-catalyzed hepatic biotransformation. Halothane is reduced under low oxygen tensions by CYP2A6 and CYP3A4 in human liver microsome to an unstable free radical, and then to the volatile metabolites chlorodifluoroethene (CDE) and chlorotrifluoroethane (CTE). The free radical is also thought to initiate lipid peroxidation. Halothane-dependent lipid peroxidation has been shown in animals in vitro and in vivo but has not been evaluated in humans. This investigation tested the hypothesis that halothane causes lipid peroxidation in human liver microsomes, identified P450 isoforms responsible for halothane-dependent lipid peroxidation, and tested the hypothesis that lipid peroxidation is prevented by inhibiting halothane reduction. METHODS: Halothane metabolism was determined using human liver microsomes or cDNA-expressed P450. Lipid peroxidation was quantified by malondialdehyde (MDA) formation using high-pressure liquid chromatography-ultraviolet analysis of the thiobarbituric acid-MDA adduct. CTE and CDE were determined by gas chromatography-mass spectrometry. RESULTS: Halothane caused MDA formation in human liver microsomes at rates much lower than in rat liver microsomes. Human liver microsomal MDA production exhibited biphasic enzyme kinetics, similar to CDE and CTE production. MDA production was inhibited by the CYP2A6 inhibitor methoxsalen but not by the CYP3A4 inhibitor troleandomycin. Halothane-dependent MDA production was catalyzed by cDNA-expressed CYP2A6 but not CYP3A4 or P450 reductase alone. CYP2A6-catalyzed MDA production was inhibited by methoxsalen or anti-CYP2A6 antibody. CONCLUSIONS: Halothane causes lipid peroxidation in human liver microsomes, which is catalyzed by CYP2A6, and inhibition of halothane reduction prevents halothane-dependent lipid peroxidation in vitro.     

Halothane-dependent Lipid Peroxidation in Human Liver Microsomes Is Catalyzed by Cytochrome P4502A6 (CYP2A6)

Background: Halothane is extensively (approximately 50%) metabolized in humans and undergoes both oxidative and reductive cytochrome P450-catalyzed hepatic biotransformation. Halothane is reduced under low oxygen tensions by CYP2A6 and CYP3A4 in human liver microsome to an unstable free radical, and then to the volatile metabolites chlorodifluoroethene (CDE) and chlorotrifluoroethane (CTE). The free radical is also thought to initiate lipid peroxidation. Halothane-dependent lipid peroxidation has been shown in animals in vitro and in vivo but has not been evaluated in humans. This investigation tested the hypothesis that halothane causes lipid peroxidation in human liver microsomes, identified P450 isoforms responsible for halothane-dependent lipid peroxidation, and tested the hypothesis that lipid peroxidation is prevented by inhibiting halothane reduction.

Methods: Halothane metabolism was determined using human liver microsomes or cDNA-expressed P450. Lipid peroxidation was quantified by malondialdehyde (MDA) formation using high-pressure liquid chromatography-ultraviolet analysis of the thiobarbituric acid-MDA adduct. CTE and CDE were determined by gas chromatography-mass spectrometry.

Results: Halothane caused MDA formation in human liver microsomes at rates much lower than in rat liver microsomes. Human liver microsomal MDA production exhibited biphasic enzyme kinetics, similar to CDE and CTE production. MDA production was inhibited by the CYP2A6 inhibitor methoxsalen but not by the CYP3A4 inhibitor troleandomycin. Halothane-dependent MDA production was catalyzed by cDNA-expressed CYP2A6 but not CYP3A4 or P450 reductase alone. CYP2A6-catalyzed MDA production was inhibited by methoxsalen or anti-CYP2A6 antibody.     

Inhibition of gluconeogenesis and <Emphasis Type="Italic">p</Emphasis>-aminohipuric acid accumulation in rat renal cortical slices by ionic and nonionic contrast media

Background. Renal dysfunction is a well-recognized complication induced by contrast media (CM). Nonionic CM have been introduced into clinical use to replace conventional ionic CM in an effort to reduce toxicity. However, the nephrotoxic effects of nonionic CM have not been fully evaluated. We previously determined the activities of N-acetyl--d-glucosaminidase and -glutamyltransferase released from rat and human renal slices incubated with contrast media. Dose-dependent enzyme release from renal slices was observed, but there was no statistical difference in the increase of enzyme activities between ionic and nonionic CM. The present experiment was conducted to compare the effects of ionic and nonionic CM on the metabolic function of rat renal slices.Methods. Rat renal cortical slices were incubated with ionic CM (diatrizoate, iothalamate) and nonionic CM (iopamidol, iohexol) at 37°C for 90min. To examine the dose–response effects of CM on gluconeogenesis and p-aminohipuric acid (PAH) accumulation in the rat renal slices, slices were incubated with 30, 60, and 90mgI/ml of CM. The inhibitory effects of nonionic CM on gluconeogenesis and PAH accumulation were compared with those of ionic CM in an independent experiment, in which slices were incubated with CM at a concentration of 60mgI/ml. In addition, rat renal slices were incubated with mannitol instead of CM to investigate the effects of osmotic pressure on gluconeogenesis and PAH accumulation.Results. A dose-dependent reduction of gluconeogenesis in rat renal slices was demonstrated by both ionic CM and nonionic CM. The inhibition of PAH accumulation was dose-dependent with nonionic CM, but not with ionic CM. Gluconeogenesis and PAH accumulation within the renal slices were both inhibited according to the increase in osmotic pressure produced by mannitol. The reduction in gluconeogenesis and PAH accumulation within the rat renal slices incubated with 60mgI/ml of nonionic CM were significantly less than those resulting from the same concentration of ionic CM.Conclusions. Nonionic CM is less nephrotoxic than ionic CM with regard to gluconeogenesis and PAH accumulation in rat renal slices. These differences in nephrotoxic effect between ionic and nonionic CM may in part be attributable to differences in osmotic pressure.     

Changes of cerebral energy metabolism and lipid peroxidation in rats leading to mitochondrial dysfunction after diffuse brain injury.

The effect of mild closed head trauma, induced by the weight-drop method (450 g from a 1-m height), on lipid peroxidation and energy metabolism of brain tissue was determined at various times after cerebral injury in spontaneously breathing rats (1, 10, 30 minutes and 2, 6, 15, 24, 48, and 120 hours). Animals were continuously monitored for the evaluation of blood pressure, blood gases, heart rate, and intracranial pressure. Analysis of malondialdehyde (MDA) as an index of lipid peroxidation, ascorbic acid, high-energy phosphates, nicotinic coenzymes, oxypurines, and nucleosides was performed by high-performance liquid chromatography (HPLC) on neutralized perchloric acid extract of the whole brain. Data showed that MDA, undetectable in control, sham-operated rats, was already present within 1 minute of trauma (1.77 nmol/g wet weight; SD = 0.29) and reached maximal values by 2 hours (72.26 nmol/g w.w.; SD = 11.26), showing a progressive slow decrease thereafter. In contrast, ATP, GTP, and nicotinic coenzyme (NAD and NADP) concentrations showed significant reduction only by the second hour postinjury. Maximal decrease of the ATP and GTP concentrations were seen at 6 hours postinjury, whereas NAD and NADP concentrations showed maximum decline by 15 hours. Values recorded in mechanically ventilated rats did not differ significantly from those obtained in spontaneously breathing animals. These findings, supported by the absence of blood gas and blood pressure changes in the spontaneously breathing rats, strongly support the premise that biochemical changes (primarily lipid peroxidation) are not caused by secondary ischemic-hypoxic phenomena but rather are triggered by these forces acting on the brain at the time of impact. In addition, these results suggest that depression of energy metabolism might be caused by peroxidation of the mitochondrial membrane with a consequent alteration of the main mitochondrial function-that is, the energy supply.     

正常人和不育者精子膜脂类过氧化反应和精子存活率的关系

为分析精子膜脂类过氧化反应（ＬＰＯ）和精子存活率之间的关系，对１０例不育症患者和１０例正常人的精子分别与０，０．１，０．２，０．４，０．８和１．６ｍｍｏｌ／Ｌ阿魏酸（一种已知的抗氧化剂）温育，以调节精子膜ＬＰＯ率。精子膜ＬＰＯ的测定采用丙二醛（ＭＤＡ）硫代巴比妥酸比色法，精子存活率的测定采用曙红Ｙ染色法。用直线回归分析两个测定值之间的关系。结果不育症患者和正常人精子膜ＬＰＯ和精子存活率之间均存在明显的负相关。特别是不育症组，相关性更为显著，与正常组相比，其精子的ＭＤＡ含量更高，存活率更低。结果提示精子膜ＬＰＯ可能是造成精子存活率降低的主要原因之一，同时为精子功能损伤所致的男性不育症提示了一条可能的临床诊断和治疗途径。     

Tubular PAH transport capacity in human kidney tissue and in renal cell carcinoma: correlation with various clinical and morphological parameters of the tumor

In vitro accumulation ofp-aminohippurate (PAH) was investigated in intact human renal cortical slices of normal kidney tissue and in tissue slices of renal cell carcinoma (RCC). The technique used was established in preliminary experiments on rat kidney tissue slices. In principle, the accumulation capacity is comparable in renal tissue slices of both species (slice to medium accumulation ratios between 4 and 8). In man sex differences in accumulation capacity do not exist. But, as shown in detail for rats, accumulation capacity drops with age. Tissue slices of RCC are unable to accumulate PAH actively; slice to medium ratio reaches about 1 and indicates passive PAH uptake only. Surprisingly, in tumors of stage pTl PAH uptake is lowest, perhaps as a sign of PAH transport out of the cells. There is no difference between peripheral and central parts of RCC. Age and sex are without influence on PAH uptake in RCC tissue slices. Interestingly, the accumulation capacity of intact tissue of kidneys infested with RCC also depends on the severity of the tumor (stage, diameter), but not on grading and formation of metastases.     

Effects of chronic cyclosporine administration on renal blood flow and intrarenal blood flow distribution

Cyclosporine-induced decreases in renal blood flow (RBF) and glomerular function are well documented. Glomerular filtration and tubular function may be affected by changes in both total renal blood flow and cortical blood flow distribution (CBFD). The effect of CsA on RBF, CBFD, glomerular filtration rate, and tubular function was studied in conscious ewes receiving a mean CsA dose of 30 mg/kg/day for 28 days with mean CsA trough levels of 344 +/- 45 ng/ml. RBF and CBFD were determined by the injection of 15 microns radioactive microspheres before and after one month of treatment with CsA or its vehicle, olive oil. RBF decreased by 24% from 7.65 +/- 0.87 to 5.79 +/- 0.42 ml/min/g of kidney in CsA-treated ewes (P = 0.014), while no decrease was noted in the control group (7.92 +/- 1.10 vs. 7.62 +/- 0.71). Intracortical blood flow decreased in proportion to the fall in total renal blood flow--thus CsA treatment did not change the cortical distribution of flow. There was a 25% decrease in GFR, as determined by inulin clearance, in the CsA-treated group (80 +/- 6 vs. 62 +/- 3 ml/min; P = 0.027) while there was a nonsignificant increase in control animals (62 +/- 11 vs. 92 +/- 7 ml/min). There was no evidence of tubular dysfunction in either group. There were also no changes in urinary excretion rates of prostaglandins PGE2, 6-keto-PGF1 alpha or thromboxane B2, nor were there changes in plasma renin activity. CsA induced decreases in RBF occur red without redistribution of cortical blood flow, indicating that altered cortical distribution of blood flow is not responsible for the changes in GFR or tubular function that have been reported. The changes in renal blood flow and glomerular filtration rate are independent of changes in renal prostaglandin production, and are likely not associated with altered plasma renin activity.