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The interaction of a bioengineered serpin (LEX032) with human leukocyte proteinase 3 (PR 3) has been investigated. LEX032 was found to be a time-dependent inhibitor of PR 3, forming a highly-stable enzyme-inhibitor complex (Ki 12 nM).

Acetaminophen (APAP)-induced nephrotoxicity is age dependent in male Sprague-Dawley rats: nephrotoxicity occurs at lower dosages of APAP in 12- to 14-month olds compared with 2- to 3-month olds. The mechanisms responsible for enhanced nephrotoxicity in 12-month-old Sprague-Dawley rats are not entirely clear, but may be related to age-dependent differences in APAP metabolism in liver and/or kidney. Major pathways of hepatic APAP metabolism include sulfation and glucuronidation; glutathione conjugation represents a pathway for detoxification of reactive oxidative APAP metabolites. The present studies were designed to quantify in vitro activity of three Phase II enzyme activities: glutathione S-transferase using 1-chloro-2,4-dinitrobenzene as substrate, UDP-glucuronyl transferase using APAP as substrate, and sulfotransferase using APAP as substrate, in subcellular fractions of liver and kidney of 3-, 12-, 18-, and 30-month-old naive male Sprague-Dawley rats. In liver, glutathione S-transferase, UDP glucuronyl transferase, and sulfotransferase activities were not significantly different in rats from 3 through 30 months of age. Renal UDP glucuronyl transferase and sulfotransferase activities were similar in rats from 3 through 30 months of age. In contrast, renal glutathione S-transferase activity was characterized by a lower Km in 12- and 30-month olds when compared with 3-month olds. These data suggest that the reduced total systemic clearance of APAP in 12-month-old male Sprague-Dawley rats previously observed cannot be attributed to age-dependent differences in hepatic APAP metabolism. In addition, it is unlikely that differences in renal APAP metabolism contribute to age-dependent APAP nephrotoxicity.

Acetaminophen (APAP)-induced nephrotoxicity is age-dependent in male Sprague-Dawley (SD) rats: middle-aged (9-12 months old) rats exhibit nephrotoxicity at lower dosages of APAP than do young adults (2-3 months old). The present study was designed to test the hypothesis that the intrinsic susceptibility of renal tissue to APAP toxicity is increased in middle-aged rats. APAP toxicity was evaluated in renal slices from naive 3- and 12-month-old male SD rats incubated with 0-50 mM APAP for 2-8 h. Renal slice glutathione (GSH) and APAP concentrations were determined; renal function was assessed by organic anion (para-aminohippurate, PAH) and cation (tetraethylammonium, TEA) accumulation; and cell viability was assessed by lactate dehydrogenase (LDH) leakage. At each concentration of APAP tested, accumulation of APAP by renal slices was similar in 3- and 12-month-olds. APAP toxicity in renal slices from both 3- and 12-month-old rats was characterized by concentration-dependent increases in LDH leakage. In contrast to APAP nephrotoxicity in vivo, APAP toxicity in renal slices was accompanied by decreased accumulation of PAH and TEA. Additionally, APAP produced marked reductions in renal slice GSH content in a concentration-dependent manner: however, in contrast to APAP nephrotoxicity in vivo, APAP-induced GSH depletion in vitro did not precede cytotoxicity. No consistent age-dependent differences in the time- and concentration-response curves for APAP nephrotoxicity were observed. These data suggest that APAP cytotoxicity in vitro is not increased in 12-month-old rats. However, since the pattern (and mechanisms) of APAP cytotoxicity in vitro appears to be different from that observed in vivo, extrapolation of in vitro cytotoxicity to in vivo nephrotoxicity is limited. Therefore, age differences in intrinsic susceptibility of the intact kidney cannot be excluded as a mechanism contributing to enhanced APAP nephrotoxicity in middle-aged rats.

Protein degradation in the kidney occurs mainly in lysosomes, organelles which may also accumulate nephrotoxic chemicals. The goal of this study was to evaluate the effects of intracellular accumulation of gentamicin, cephaloridine and cisplatin on lysosomal digestion of the protein lysozyme. Gentamicin (15 or 30 mg/kg/day for 3 or 5 days), cisplatin (2.5 or 5 mg/kg) or cephaloridine (500, 1000, 2000 or 2500 mg/kg) was administered ip to male Wistar rats. The main site of the nephrotoxic effects of these compounds was the proximal tubule where these agents differentially affected S1, S2 and/or S3 segments. A 2- and 4-fold increase of the excretion of N-acetyl-beta-D-glucosaminidase (NAG) was observed in the urine from cisplatin- and gentamicin-treated rats, respectively; no change in enzyme excretion occurred after cephaloradine. One hour prior to sacrifice, rat were given 0.3 mg of unlabelled lysozyme in combination with 125I-lysozyme in 0.3 mL saline. Renal cortical slices were prepared and incubated for 15, 30, 60 and 90 min. Release of trichloroacetic acid (TCA) soluble radioactivity into the medium was assumed to quantify lysosomal degradation of lysozyme. Accumulation of p-amino-hippurate (PAH) in renal cortical slices and changes in blood urea nitrogen (BUN) concentration were used as indices of renal damage. TCA-soluble radioactivity increased in the medium from kidney slices from control rats to 50% of the total radioactivity after 90 min incubation. In gentamicin-treated rats, lysozyme degradation was significantly decreased by doses of 15 and 30 mg/kg/day after 3 and 5 days of exposure in the absence of any changes in BUN or PAH accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure to polybrominated biphenyls (PBBs) resulted in increased activity of microsomal arylhydrocarbon hydroxylase and ethoxyresorufin-O-deethylase in rat lung. Clearance of 5-hydroxytryptamine (5-HT) and angiotensin 1 by perfused lungs was decreased by PBBs. However, PBBs had no effect on the activity of epoxide hydrolase, monoamine oxidase, or angiotensin-converting enzyme in lung. The only histopathologic change detected in lungs from PBB-treated rats was an increase in alveolar type II cell lamellar bodies. Selective accumulation of certain PBB congeners by lung was not observed in this investigation.

Elevated concentration of aluminum has been reported in serum, whole blood and tissue samples of patients with renal insufficiency. Evidence incriminating aluminum as a neurotoxin among the dialysis population is strong. The source of this aluminum has not been clearly defined, although both gastrointestinal and parenteral routes may be involved. Data from this laboratory suggest that an effect of parathyroid hormone on tissue aluminum burdens may, in part, explain why only certain patients exposed to high dialysate aluminum develop the dialysis encephalopathy syndrome and the occasional occurrence of this syndrome in the absence of dialysis or increased dialysate aluminum.

Preincubation of renal cortical slices with chloroform (CHCl3) from male, but not female, mice resulted in a subsequent decrease of the ability of the slices to accumulate the organic ions, p-aminohippurate (PAH) and tetraethylammonium (TEA). These sex-related differences, the time required for manifestation of this effect (60 to 90 min), and the concentration dependency (0 to 50 mumol, 0 to 4 microliter CHCl3) were similar to in vivo observations on CHCl3 nephrotoxicity in mice. Furthermore, an equimolar concentration of deuterated CHCl3 (CDCl3) in vitro was less effective than CHCl3 in decreasing PAH and TEA accumulation in male renal cortical slices. The effects of CHCl3 on PAH and TEA accumulation could be diminished or blocked by preincubation with CHCl3 in the presence of carbon monoxide or at 0 degrees C, respectively. The nephrotoxicity of CHCl3 in vitro was increased in renal cortical slices from male mice pretreated with diethyl maleate. Thus, this in vitro model with mouse renal cortical slices and the sex-related differences in CHCl3 nephrotoxicity suggests that the kidney may metabolize CHCl3 in situ to a nephrotoxic metabolite.

Various ketonic agents potentiate the hepatic and renal toxicity of halogenated solvents in mice and rats. Characteristics of CHCl3 nephrotoxicity and of 2-hexanone potentiation were evaluated in adult male Fischer 344 rats pretreated with vehicle (oil, 10 ml/kg, po) or 2-hexanone (10 mmol/kg, po) 18 hr prior to CHCl3 exposure. In contrast to the liver, little metabolism of 14CHCl3 by renal cortical microsomes from vehicle- or 2-hexanone-pretreated rats was detected. However, CHCl3 produced a concentration-related dysfunction when added to renal cortical slices from Fischer 344 or Sprague-Dawley rats. The degree of CHCl3 toxicity in vitro was not altered when renal cortical slices were preincubated with CHCl3 (8.5 microliter) under an atmosphere of carbon monoxide. In renal cortical slices, deuterated-CHCl3 was less toxic than CHCl3. Although 2-hexanone pretreatment increased renal slice metabolism of 14CHCl3 twofold, this increase was not associated with an increase in nephrotoxicity after direct exposure of slices to CHCl3 (0 to 10 microliter) in vitro. CHCl3 (0.5 ml/kg, ip) did not alter renal cortical glutathione concentrations in vehicle or 2-hexanone pretreated rats. The association of 14CHCl3-derived radiolabel was increased over control by 2-hexanone pretreatment in protein, lipid, and acid soluble fractions from the renal cortex by approximately two-, two-, and fivefold, respectively. In conclusion, renal cytochrome P-450 did not appear to mediate CHCl3 metabolism and nephrotoxicity in the rat to the extent observed previously in mice. 2-Hexanone appeared to potentiate nephrotoxicity by a mechanism different than that observed in rat liver.

Penicillin pretreatment enhanced the rate of PAH uptake into separated proximal tubules (collagenase digestion) from 2-week New Zealand white rabbits. A double reciprocal plot of these data suggests that penicillin increases the maximal velocity of PAH uptake. Na, K-ATPase was less in adult tissue but was unaffected by penicillin. No ultrastructural changes could be attributed to the treatment. Thus substrate stimulation of PAH transport does not involve Na, K-ATPase and probably involves soluble, rather than structural proteins.

The pulmonary vasculature has been implicated in the clearance of several vasoactive substances from the circulation including angiotensin I (AI). In view of the previously reported age-related differences in angiotensin-converting enzyme (ACE) activity of lung homogenates, it was of interest to examine the ability of intact perfused lungs to metabolize AI. Lungs from newborn and adult rats were perfused with Krebs bicarbonate buffer containing 1.0 ng/ml AI in a single-pass, nonrecirculating system. The rate of perfusion was normalized to lung mass. Removal of AI was determined from the transpulmonary difference in radioimmunoassayable AI. Lungs from 7-day-old rats removed a smaller fraction of AI from the circulation than did adult lungs. The age-related increase in AI clearance was accompanied by an increase in pulmonary ACE content; however, enzyme content alone could not account for the observed differences. The increased metabolism of AI by the pulmonary vasculature during development may contribute to the age-related increase in circulating angiotensin II concentrations.

Polybrominated biphenyls (PBBs) have produced a variety of effects including alterations in the endocrine system and in the activity of microsomal mixed-function oxidases (MFOs). Because steroid hormones are substrates for MFOs, effects of PBBs on the endocrine system may be a consequence of enhanced steroid hormone catabolism. Therefore, as a first step in evaluating the effect of PBBs on steroid hormone catabolism. Therefore, as a first step in evaluating the effect of PBBs on steroid hormone metabolism, it was of interest to determine effects of perinatal exposure to PBBs on the response to exogenously adminstered steroid hormones. Rats were exposed to 0, 10, or 100 ppm PBBs from d 8 of gestation until d 28 postpartum, when experiments were conducted. Responses to labeled steroid hormones were generally modified in a manner directly related to PBB dose and were correlated with changes in serum and target tissue retroactivity. Stimulated metabolism of steroid hormones may account, at least in part, for endocrine-related alterations produced by PBBs. Although the potential for decreased reproductive capacity following PBBs cannot yet be accurately predicted, these experiments suggest that fertility may be reduced following PBBs as a consequence of accelerated steroid hormone metabolism and/or excretion.

The ability of newborn and adult rats to eliminate p-aminohippuric acid and inulin from plasma was determined. The pattern of development is similar to that observed in vitro using renal cortical slices. The fact that function increases to a peak and then declines over the developmental period while organ weight and histology mature progressively suggests a divergence of functional and antomical maturation. Inulin elimination, unlike PAH, increased over the ages tested, and is apparently more closely related to organ growth.

This study was undertaken to investigate the effects of pre- and/or postnatal maternal protein deprivation (PD) on renal functional development in the offspring. Pregnant rats were fed either a control (24% protein) or low (8 or 10%) protein diet during gestation and lactation. Progeny of these dams were cross-fostered at birth, yielding four experimental groups: pups born of control dams and nursed by PD or control dams and pups born of PD dams and nursed by control or PD dams. While the effects of prenatal PD on body and kidney growth were negligible, PD during the nursing period appeared to have a more profound effect on body and kidney weight. Renal transport functions, quantified in vitro, were differentially affected by these dietary manipulations. Renal transport capacity for organic acids and bases was depressed in pups nursed by PD dams. Maturation of the renal organic acid transport system was also delayed in these pups. alpha-Aminoisobutyric acid accumulation by renal cortical slices was enhanced only in 10-day old rats stressed by pre- and postnatal maternal PD. Renal gluconeogenic and ammoniagenic capacity was not impaired by these dietary manipulations. No differences in protein or water content of renal cortical slices were observed.

The effect of tolmetin on prostaglandin synthesis by minces of rat renal medulla and on prostaglandin cyclooxygenase of rabbit renal medulla was determined in vitro. The effect of tolmetin was compared to the effects of indomethacin and ibuprofen. Pretreatment of rats in vivo with tolmetin, indmethacin or ibuprofen reduced prostaglandin synthesis by minces of renal medulla. Incubation of medullary tissue in medium containing tolmetin or indomethacin also decreased prostaglandin production. Both drugs reduced O2 consumption by prostaglandin cyclooxygenase from rabbit renal medulla. In addition, the effect of tolmetin, indomethacin and ibuprofen on renal blood flow and the intrarenal distribution of renal blood flow was measured in anesthetized dogs. Tolmetin and ibuprofen resemble indomethacin in reducing renal blood flow and in shifting the distribution of renal cortical flow from the inner cortex toward the outer cortex. It is concluded that tolmetin is an effective inhibitor of prostaglandin synthesis and affects renal function in a fashion similar to other prostaglandin synthesis inhibitors.

Strain differences in susceptibility of rats to acetaminophen (APAP)-induced nephrotoxicity have been reported previously. Young adult male Fischer 344 (F344) rats are susceptible, whereas weight-matched Sprague-Dawley (SD) rats are not susceptible to APAP nephrotoxicity. Susceptibility to APAP nephrotoxicity is also age dependent, at least in F344 rats. Middle-aged (12-15 months old) male F344 rats are more susceptible to APAP-induced nephrotoxicity than are young adult (2-4 months old) males. APAP nephrotoxicity in aging SD rats has not been evaluated. The present studies were designed to define strain differences in the nephrotoxicity of APAP and p-aminophenol (PAP), a nephrotoxic metabolite of APAP, using 2-, 3-, and 9- to 12-month-old F344 and SD rats. At 2 months of age, F344, but not SD, rats were susceptible to APAP-induced nephrotoxicity. However, at 3 months of age, strain differences were less marked, as susceptibility to APAP nephrotoxicity appeared to increase between 2 and 3 months of age only in SD rats. By 9-12 months of age, susceptibility to APAP nephrotoxicity was comparable in F344 and SD rats. No age- or strain-related differences were observed in the excretory pattern of urinary APAP and metabolites that might explain the increased susceptibility of aging rats to APAP nephrotoxicity. Strain differences in age-matched rats were not marked for PAP-induced nephrotoxicity. Susceptibility of both 3- and 12-month-old F344 and SD rats to PAP-induced nephrotoxicity was greater compared to strain-matched 2-month-old rats. In both F344 and SD rats, PAP nephrotoxicity increased only modestly between 3 and 12 months of age, indicating that increased susceptibility to PAP probably does not play a major role in the age-dependent increase in APAP nephrotoxicity. Thus, strain differences in APAP nephrotoxicity decrease with advancing age. The mechanisms mediating the increased susceptibility to APAP nephrotoxicity in middle-aged rats are not known but may relate, at least in part, to age-dependent differences in pharmacokinetics. The present study highlights the importance of considering the age of rats when evaluating drug toxicity. Even in young adult rats, subtle maturational changes in drug metabolism and/or disposition may occur, making toxicological evaluation in weight-matched rats of different strains and ages inappropriate.

Preparation and incubation of renal cortical slices from adult, female, New Zealand white rabbit depleted tissue citrate concentration. Acetate (10.0 mM) in the incubation significantly increased slice citrate concentration and p-aminohippurate (PAH) accumulation. Physiological concentrations of citrate increased PAH accumulation and final medium pH. increasing concentrations of citrate produced a biphasic effect on PAH accumulation. These data suggested that citrate may act as an intracellular modulator of organic anion transport. This hypothesis was tested with other stimulators of PAH accumulation. Physiological concentrations of alpha-ketoglutarate or succinate increased slice accumulation of PAH. Higher concentrations of either substrate significantly inhibited PAH accumulation. Final medium pH increased with increased medium concentration of both substrates. alpha-Ketoglutarate (0.5 mM) increased PAH accumulation but had no effect on slice citrate concentration. Glucose did not alter either PAH accumulation or slice citrate concentration. Slices incubated without substrate were depleted of citrate but not of alpha-ketoglutarate. Acetate (1.0 mM) significantly increased slice concentration of both alpha-ketoglutarate and citrate. These data suggested that organic anion transport could be modulated by several metabolic intermediates acting through similar but separate mechanisms.

The renal organic anion transport system has been linked to the selective extraction of nonesterified fatty acids (NEFA) from arterial blood. Consequently, p-aminohippurate (PAH) and palmitate may compete for a common intracellular binding site or may be handled by a common enzymatic pathway. The purpose of this study was to identify sites of interaction by correlating alterations in PAH accumulation and palmitate metabolism after selective stimulation of the PAH transport system. Penicillin treatment of immature rabbits increased PAH accumulation by suspensions of proximal tubules prepared nonenzymatically) and altered distribation of incorporated palmitate[14C] within tubule lipid classes. Penicillin increased palmitate[14C] esterified to triglycerides and decreased 14C recovered as NEFA. Administration of iodipamide had no effect on PAH accumulation and did not alter palmitate utilization. Penicillin treatment of mature rabbits did not alter either tubule PAH accumulation or palmitate esterification. These results suggested that palmitate and PAH share a common intracellular binding site and that penicillin enhanced PAH accumulation by removing endogenous inhibitors (NEFA).

Female SD rats were maintained for approximately 1 year on diets containing 300 ppm N-2-fluorenylacetamide (2-FAA), 50 ppm polybrominated biphenyls (PBB), or a combination of these chemicals (PBB + 2-FAA). Ingestion of 2-FAA significantly reduced the average survival time of the rats; this effect was virtually blocked by the simultaneous ingestion of PBB. Simultaneous ingestion of PBB also significantly reduced the overall incidence of 2-FAA-induced tumors during the examination period. The lower incidence of tumorigenesis was accompanied by an increase in the latency time for tumor induction; tumors were found in 100% of the animals given 2-FAA after 29 weeks of carcinogen ingestion, whereas only 50% of the PBB + 2-FAA-fed animals had tumors at the end of the experiment (53 wk of carcinogen ingestion). PBB significantly reduced the incidence of 2-FAA-induced tumors at nonhepatic locations (mammary gland and ear duct) but did not affect the incidence of hepatic tumors to a statistically significant extent. PBB ingestion did not significantly increase the incidence of tumors when compared with controls; 1 tumor was found in 1 of 12 rats fed 50 ppm PBB for 57 weeks, and no tumors were detected in 8 controls.

Middle-aged male Sprague-Dawley (SD) rats (9-12 months) are more susceptible to acetaminophen (APAP)-induced nephrotoxicity than are young (2-3 months) adult males. The present studies were designed to evaluate the role of pharmacokinetics and renal and hepatic metabolism of APAP in age-dependent nephrotoxicity. Following 750 mg/kg APAP, ip, a nephrotoxic dosage in 12-month-old but not 3-month-old rats, renal cortical APAP concentrations were significantly greater in 12-month-old compared with 3-month-old SD rats at 3, 4, and 6 hr after treatment. Renal medullary APAP concentrations in 12 month-old rats were significantly greater than in 3-month-old rats at 2, 3, and 5 hr after treatment. Serum APAP concentrations were significantly elevated in 12-month-old compared with 3-month-old rats from 2 through 5 hr after APAP (750 mg/kg ip). However, APAP tissue/serum concentration ratios were similar in 3- and 12-month-old rats, indicating that differences in tissue concentration were secondary to increased serum concentrations in older rats. Conjugated APAP metabolites in blood were similar in 3- and 12-month-olds during the initial 2-3 hr after 750 mg/kg APAP, ip, but began to accumulate in 12-month-old but not 3-month-old rats within 6-8 hr after APAP administration, perhaps secondary to declining renal function. After 500 mg/kg APAP, iv, blood APAP concentrations were markedly elevated in 12-month-old compared with 3-month-old rats during the entire course of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Experiments were performed on newborn piglets 6--96 hr of age. When the respiratory dead space was increased arterial pO2 decreased and pCO2 increased. During this time cardiac output was unchanged (Fig. 1), while heart rate, respiratory rate, and blood pressure increased (Figs. 2 and 3). After 90 min of asphyxia blood flow to the stomach and small and large intestines decreased. Changes in blood flow were associated with dilatation of segments of the small and large intestine with scattered areas of hemorrhage. Pathologic examination revealed scattered areas of mucosal necrosis (Fig. 6).

In mice, only males are susceptible to chloroform (CHCl3) nephrotoxicity and the susceptibility appears to be related to renal mixed function oxidase activity. There were sex-related differences of renal cytochrome P-450 and b5 concentrations and of ethoxycoumarin O-deethylase activity in mouse kidneys; in all cases activity was higher in males. Castration of male mice eliminated susceptibility to CHCl3 nephrotoxicity and reduced renal mixed function oxidases to concentrations observed in female mice. Treatment of male and female mice with testosterone increased the susceptibility to CHCl3 nephrotoxicity and increased renal mixed function oxidases to similar activities in both sexes. Previous data have suggested that CHCl3 is metabolized in situ by the kidney, possibly by a mechanism similar to that occurring in the liver. The data from this investigation are consistent with the concept that CHCl3 is metabolized by a cytochrome P-450-dependent mechanism in the kidney.

To evaluate the hypothesis that cytochrome P-450 mixed-function oxidase (MFO) activity may have a causal role in the production of cephalosporin nephrotoxicity, the effects of the MFO inhibitors cobaltous chloride and piperonyl butoxide on the nephrotoxicity of cephaloridine in the rabbit were examined. Although cobaltous chloride had no effect on cephaloridine nephrotoxicity, piperonyl butoxide had a significant protective effect. However, in correlated studies of the effects on the renal cortical uptake and disappearance of cephaloridine, it was found that piperonyl butoxide significantly reduces (by 50%) the cortical concentrations of the cephalosporin, both decreasing its uptake by and increasing its disappearance from tubular cells. Finally, we evaluated the effect of piperonyl butoxide on the nephrotoxicity of cephaloglycin, a more toxic cephalosporin that lacks the thiophene side-ring proposed as the target of MFO activation in earlier studies with cephaloridine. No protection against cephaloglycin was found. It is concluded that these inhibitors of MFO activity do not reduce cephalosporin nephrotoxicity in general, and that the reduction of cephaloridine toxicity by piperonyl butoxide can be explained by an effect on the intracellular concentrations of that particular cephalosporin.

A 1-year-old child with severe acetaminophen (APAP) poisoning after ingestion of 10 gm APAP demonstrated central nervous system depression, shock, hypothermia, and metabolic acidosis. There was dramatic improvement during treatment with intravenously administered N-acetylcysteine (NAC) and hemodialysis, and the patient recovered without sequelae. A detailed study of APAP metabolism was carried out during the initial 72 hours after ingestion. APAP-sulfate and APAP-glucuronide accounted for 29% and 33%, respectively, of total drug in urine, whereas cysteine and NAC conjugates accounted for only 12%. The low incidence of severe toxicity in children after overdoses of APAP may be related to greater capacity to metabolize APAP via a nontoxic pathway.

To understand the nephrotoxicity of xenobiotics, the species, strain, sex, and the presence of other chemicals must be considered. This review has considered the importance of these factors in determining the nephrotoxic liability of a drug. For example, cephaloridine is more nephrotoxic in rabbit than rats and is least nephrotoxic in mice. This species-dependent susceptibility to cephaloridine nephrotoxicity appears to be related to the degree in which cephaloridine depletes renal cortical glutathione. Additionally, only male mice of certain strains are susceptible to chloroform-induced nephrotoxicity. Lastly, the presence of certain ketones or ketogenic substances such as acetone and hexane enhance chloroform-induced nephrotoxicity in male Sprague-Dawley rats. Knowing which factors can enhance or limit nephrotoxicity of drugs will lend to a better understanding of the mechanism of these toxicities as well as to design compounds with lesser toxicities.

The ability of indoprofen or sodium indoprofen to inhibit phenylquinone-writhing and renal prostaglandin synthesis was determined in mice following a single oral dose of either drug. Male mice (4/group) were treated with 1.5 mg/kg indoprofen or sodium indoprofen. Inhibition of phenylquinone-writhing was determined at 2, 4, 8, 16 and 32 hr post treatment. Animals were sacrificed and blood collected for determination of plasma indoprofen concentration. Kidneys were removed and prepared for determination of renal prostaglandin synthesis by an in vitro technique. Phenylquinone-writhing was significantly depressed by both preparations at 2 and 4 hr post treatment. Sodium indoprofen also significantly depressed writhing at 8 hr post treatment. Renal prostaglandin synthesis, like phenylquinone-writhing, was significantly depressed at 2 and 4 hr after drug treatment. Plasma indoprofen concentration was correlated with both inhibition of phenylquinone-wrighing and inhibition of renal prostaglandin synthesis. When writhes were plotted versus prostaglandin synthesis, a positive correlation was observed suggesting a temporal relationship between inhibition of phenylquinone-writhing and inhibition of renal prostaglandin synthesis.

These experiments were designed to demonstrate that pretreatment of newborn dogs with penicillin will enhance maturation of the renal organic anion transport system in vivo. Littermate pups were injected with procaine penicillin G (300,000 I.U./kg b.i.d. for 3 days) or saline before 2 weeks of age. Animals were surgically prepared on day 16 or 17. Transport of p-aminhippurate (PAH), as an indicator of renal organic anion transport, was quantified by the following procedures: 1) disappearance of a bolus injection from the plasma, 2) renal extraction and 3) rate of secretion in steady-state clearance experiments. The renal handling of insulin was measured simultaneously in all procedures for comparison. Penicillin-treated animals excreted a single intravenous bolus of PAH more rapidly than control animals, with the T1/2 decreased and the constant of elimination (Ke) increased. The extraction of PAH by kidneys of penicillin-treated animals was 165% that of controls. Similarly, the tubular secretion of PAH was increased in treated pups. These data confirm that in newborn animals the renal handling of organic anions in vivo is enhanced by pretreatment with a substrate of the secretory system.

Three divalent platinum compounds, cis-dichlorodiammineplatinum (cis-DDP), trans-dichlorodiammineplatinum (trans-DDP), and ammonium tetrachloroplatinate, were examined for their effects on glucose metabolism in male F-344 rats. Rats were treated with a single iv dose of cis-DDP (0, 2.5, or 5 mg/kg), trans-DDP (0, 5, 7.5, or 15 mg/kg) or tetrachloroplatinate (0, 6, or 18 mg/kg). Glucose tolerance was evaluated 2, 4, 7, and 14 days following platinum treatment by serially measuring plasma glucose before and following an ip glucose load. Administration of 5 mg/kg cis-DDP impaired glucose tolerance on Days 2 and 4, but not on Days 7 and 14. Plasma immunoreactive glucagon (IRG) was elevated at all times following cis-DDP treatment and thus was not correlated with the transient impairment in glucose tolerance. Plasma immunoreactive insulin (IRI) response to a glucose load was deficient relative to the degree of hyperglycemia in cis-DDP-treated (5 mg/kg) animals on Days 2 and 4. However, neither histopathological damage of the pancreas nor pancreatic stores of IRI were affected by cis-DDP treatment. In contrast to cis-DDP, equimolar or greater than equimolar doses of trans-DDP or tetrachloroplatinate did not significantly affect glucose tolerance at any time examined. These results indicate that cis-DDP-mediated glucose intolerance is unique to the geometry of the complex and is related to properties other than the presence of a divalent platinum atom. Furthermore, glucose intolerance following cis-DDP treatment appears to be related to a relative deficiency in insulin secretion.

Renal and hepatic microsomal enzyme activities were measured in ICR male mice treated with phenobarbital (PB), 3-methylcholanthrene (3MC), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or polychlorinated biphenyls (PCB). The effect of these agents on subsequently administered single doses of chloroform (CHCI3) were also determined. 3MC, TCDD and PCB increased renal as well as hepatic microsomal enzyme activities. PB increased hepatic but not renal microsomal enzyme activities. The hepatotoxicity of CHCI3 was increased by pretreatment with PB but decreased by pretreatment with TCDD. 3MC and PCB were without effect on CHCI3-induced liver damage. Pretreatment with 3MC, TCDD or PCB reduced the renal toxicity of CHCI3, but PB had no effect on CHCI3-induced kidney damage. Since at least one product of enzymatic metabolism of CHCI3 is believed to be a toxic, reactive intermediate the differential effects of inducers of microsomal drug-metabolizing enzyme activities on the renal and hepatic toxicities of CHCI3 strongly suggest that the CHCI3 metabolite(s) ultimately responsible for renal and hepatic damage are not generated at a common site. That is the metabolite responsible for hepatic is probably generated in the liver and the metabolite responsible for renal damage is probably generated in the kidney.

The effects of renal development on the response of newborns to acetazolamide were determined in an animal model, 5- and 20-day-old piglets. Increasing doses of acetazolamide increased both sodium and potassium excretion in 5-day-old piglets. Sodium excretion increased from 1.89 muEq/min during control periods to 15.7 muEq/min during infusion of acetazolamide (75 mg/kg/h). Potassium excretion increased to 20 muEq/min during acetazolamide infusion and urine pH increased from 5.7 to over 8.0. Sodium excretion by 20-day-old piglets given acetazolamide was similar to that of 5-day-old piglets but potassium excretion was twice as great (40 muEq/min). Changes in urine pH of the two groups were identical. It is concluded that the natriuretic response of 5-day-old piglets to acetazolamide is similar to that of older animals. In newborn piglets, moderate increases in sodium excretion by acetazolamide were accompanied by a marked kaliuresis. These data may identify a role for carbonic anhydrase in potassium excretion by newborn similar to that of adults.

The realtionship between in vitro prostaglandin production by renal medullary tissue and hypertension was investigated in three models of hypertensive rat, i.e., DOCA, Goldblatt and SHR. Medullary minces were incubated for 30 minutes. Following incubation tissue PGE2 concentration was quantified using mass fragmentography. Media PGE2 concentrations were quantified using radioimmunoassay. Concentrations of PGE2 in tissue from Goldblatts and SHRs were significantly less than normotensive controls. The concentration of PGE2 in media after incubating SHR tissue was significantly less than normotensives. The data suggest that alterations in PGE2 metabolism are similar in Goldblatt and SHR hypertension.

The effects of furosemide on stimulation of renin secretion and urinary sodium excretion were studied in dogs pretreated with the prostaglandin synthetase inhibitors, indomethacin and meclofenamate. Pretreatment with these drugs failed to modify the natriuretic response to furosemide but completely blocked the rise in arterial plasma renin concentration produced by the diuretic. The organic acid probenecid did not affect either the natriuretic response or the increase in renin. In separate experiments, it was not possible to separate the effects of indomethacin on prostaglandin secretion, the renin-angiotensin system or renal hemodynamics. It is concluded that in the dog the natriuretic response to furosemide is not linked to the possible prostaglandin-induced increase in renal blood flow. Indomethacin apparently affects furosemide-induced renin secretion at both the vascular and macula densa sites. The data also suggest that the prostaglandins may be more important than the renin-angiotensin system in the modulation of intrarenal hemodynamics.

Cephaloridine produces renal cortical injury, but the precise mechanism responsible for this nephrotoxicity remains unclear. Recently cephaloridine has been shown to deplete reduced glutathione (GSH) concentration selectively in renal cortex. Cephaloridine nephrotoxicity can be potentiated by diethyl maleate (a GSH depletor), but no glutathione conjugate can be detected. Thus, it was of interest to investigate further the mechanism of depletion of renal cortical GSH by cephaloridine. In the present study, cephaloridine markedly decreased GSH in rat and rabbit renal cortex while concomitantly increasing oxidized glutathione (GSSG). Furthermore, cephaloridine increased lipid peroxidation specifically in renal cortical cells. Conjugated diene formation (an index of lipid peroxidation) was increased in renal cortex but not in the liver shortly following administration of cephaloridine. Removal of selenium and/or vitamin E from the diet, which should enhance lipid peroxidation, potentiated cephaloridine nephrotoxicity and enhanced cephaloridine-induced morphological damage in the kidney. These findings are consistent with a major role of lipid peroxidation in the etiology of cephaloridine nephrotoxicity.