An integrated environmental approach to investigate biomarker fluctuations in the blue mussel Mytilus edulis L. in the Vilaine estuary, France.

Estuarine areas represent complex and highly changing environments at the interface between freshwater and marine aquatic ecosystems. Therefore, the aquatic organisms living in estuaries have to face highly variable environmental conditions. The aim of this work was to study the influence of environmental changes from either natural or anthropogenic origins on the physiological responses of Mytilus edulis. Mussels were collected in the Vilaine estuary during early summer because this season represents a critical period of active reproduction in mussels and of increased anthropogenic inputs from agricultural and boating activities into the estuary. The physiological status of the mussel M. edulis was evaluated through measurements of a suite of biomarkers related to: oxidative stress (catalase, malondialdehyde), detoxication (benzopyrene hydroxylase, carboxylesterase), neurotoxicity (acetylcholinesterase), reproductive cycle (vitelline, condition index, maturation stages), immunotoxicity (hemocyte concentration, granulocyte percentage, phagocytosis, reactive oxygen species production, oxidative burst), and general physiological stress (lysosomal stability). A selection of relevant organic contaminant (pesticides, (polycyclic aromatic hydrocarbons, polychlorobiphenyls) was measured as well as environmental parameters (water temperature, salinity, total suspended solids, turbidity, chlorophyll a, pheopigments) and mussel phycotoxin contamination. Two locations differently exposed to the plume of the Vilaine River were compared. Both temporal and inter-site variations of these biomarkers were studied. Our results show that reproduction cycle and environmental parameters such as temperature, organic ontaminants, and algal blooms could strongly influence the biomarker responses. These observations highlight the necessity to conduct integrated environmental approaches in order to better understand the causes of biomarker variations.

Integrated use of biomarkers in the mussel Mytilus galloprovincialis for assessing off-shore gas platforms in the Adriatic Sea: results of a two-year biomonitoring program.

Despite a large number of gas platforms existing in the Adriatic Sea, which is a semi-enclosed basin characterized by a slow turnover rate and increasing industrial as well as other anthropogenic activities, the effects of these structures on the aquatic ecosystem require further investigation. Since 1998, multidisciplinary studies have been performed by CNR-ISMAR to comply with legislation and to support the development of protocols for the monitoring of offshore activities in the Adriatic Sea. The present study was developed to implement a biomonitoring plan to assess the ecotoxicological effects of the extraction activities of an off-shore gas platform. Biomarkers were evaluated in mussels collected from the platform in relation to physiological stress, DNA damage, cellular damage, oxidative stress and exposure effects. Organic contaminants and trace element bioaccumulation were also assessed in the soft body of the mussels to correlate bioaccumulation of pollutants with biomarker responses. The results indicate an absence of platform-related environmental stress.

Polycyclic aromatic hydrocarbons concentrations and biomarker responses in the clam Ruditapes decussatus transplanted in the Ria Formosa lagoon.

Clams Ruditapes decussatus were transplanted in the Ria Formosa lagoon and the variation of PAH concentrations in the whole soft tissues measured, along with a suite of biomarkers, including the following: (a) phase I and phase II metabolism of xenobiotics enzymes: benzo[a]pyrene hydroxylase (BPH) and glutathione S-transferase (GST); (b) antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidases and (c) lipid peroxidation (LPO) levels. Individual PAHs were differently accumulated and eliminated by R. decussatus. During the metabolisation of PAHs by R. decussatus BPH was clearly induced in the digestive gland. Moreover, ROS lead to the induction of protective antioxidant enzymes still causing oxidative damage to membranes. Therefore, BPH seems to be a relevant indicator of PAHs in R. decussatus.

Endocrine Disruptors in Mediterranean top marine predators.

BACKGROUND, AIMS AND SCOPE: Man-made Endocrine Disruptors (EDs) range across all continents and oceans. Some geographic areas are potentially more threatened than others: one of these is the Mediterranean Sea. Levels of some xenobiotics are much higher here than in other seas and oceans. In this paper we review the final results of a project in which the hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDs was investigated. METHODS: In a four-year survey on the Mediterranean population of swordfish (Xiphias gladius), the potential toxicological effects of organochlorine compounds (OCs) on specimens of swordfish and tuna fish (Thunnus thynnus thynnus), caught in the spawning seasons from 1999 to 2002 in the Straits of Messina, Sicily (Italy), were investigated using vitellogenin (Vtg), Zona radiata proteins (Zrp), and cytochrome P4501A (CYP1A) activities (EROD, BPMO). Tissues (skin and blubber) were obtained from Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus from the western Ligurian Sea, between Corsica and the French-Italian coast, and Ionic Sea using biopsy darts launched with a crossbow. Benzo(alpha)pyrene monoxigenase (BPMO) activity was mesured in biopsies and cholrinated hydrocarbon levels were detected. RESULTS AND DISCUSSION: We illustrate the need to develop and apply sensitive methodological tools, such as biomarkers (Vitellogenin, Zona Radiata proteins and CYP1A activities) for evaluation of toxicological risk in Xiphias gladius and Thunnus thynnus thynnus), and nondestructive biomarkers (CYP1A activities and fibroblast cell culture in skin biopsy), for the hazard assessment of threatened marine mammals species (Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus) exposed to EDs. CONCLUSION: The present research shows that: a) Vtg and Zrp can be used as diagnostic tools for fish stocks hazard assessment in the Mediterranean Sea; b) that CYP1A1 (BPMO) induction in cetaceans skin biopsy may be an early sign of exposure to EDs such as OCs and a potential alert for transgenerational effects. RECOMMENDATION AND OUTLOOK: This research represents a warning signal of the potential reproductive alterations in marine top predators and suggest the need for continuous monitoring to avoid reductions in population and biodiversity in the Mediterranean Sea.

Applicability of the black slug Arion ater for monitoring exposure to polycyclic aromatic hydrocarbons and their subsequent bioactivation into DNA binding metabolites.

The applicability of terrestrial black slugs Arion ater (Mollusca, Gastropoda) was studied for biomonitoring environmental exposure to polycyclic aromatic hydrocarbons (PAHs). In laboratory experiments, slugs were orally exposed to benzo[a]pyrene (BaP) for a short term (3 days) or a long term (119 days) period. Test animals were collected in the field, or were reared under laboratory conditions to ensure that they had no history of PAH-exposure. Benzo[a]pyrene hydroxylase (BPH) activity was measured in the digestive gland as a biomarker for BaP exposure. Bulky DNA adduct formation in kidney was measured as an effect biomarker for BaP bioactivation into DNA-binding metabolites. Although success of clutching was relatively low (5 out of 18 slugs produced egg packages), sufficient number of slugs were obtained to perform exposure experiments due to high hatching (89%) and survival rates (79%). After a short exposure to a relatively high BaP doses of 20 and 200 microg/g fresh feed, a dose-dependent and significant increase of BPH activity and bulky DNA adduct levels could be demonstrated in A. ater. Induction factors were low (two times control level), but optimization of the test conditions yielded a higher BPH induction factor of 4.8 times control level. BPH activity and bulky DNA adduct levels, however, did not increase after a long-term exposure to environmentally relevant BaP doses (upto 0.25 microg/g fresh feed). Based on this lack of response after realistic exposure it is concluded that A. ater is not sensitive to BaP exposure and, therefore, not suitable for monitoring environmental exposure to PAHs.

Cytochrome P450, acetylcholinesterase and gonadal histology for evaluating contaminant exposure levels in fishes from a highly eutrophic brackish ecosystem: the Orbetello Lagoon, Italy.

Biochemical markers and ovarian histology were investigated in prespawning females of grass goby (Zosterisessor ophiocephalus) and grey mullet (Mugil cephalus) collected, respectively, in late spring and summer 2000 in four sites of a highly eutrophic brackish ecosystem of central Italy, the Orbetello Lagoon. Exposure to chlorinated and aromatic hydrocarbons was evaluated in fish livers by the somatic liver index (SLI) and by measuring 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (BaPMO) activities. Acetylcholinesterase (AChE) activity was measured in brain and gills to evaluate exposure to organophosphates (OPs) and carbamates (CBs). The gonad somatic index (GSI) was used to confirm ovarian maturation and ovarian histology was investigated as a potential biomarker for environmental effects. Samples from the Western Basin, near a sewage treatment plant (STP) off the town of Orbetello, showed higher SLI values and higher EROD and BaPMO activities than those collected from the Ansedonia Canal (AC) in the Eastern Basin (p<0.05) and respect to those from reference sites: the Albegna River (AR) Delta for grass goby and the Nassa Canal (NC), connected with the sea, for grey mullet both located in the Western Basin as well. Low brain AChE activity was observed in both species from the reference sites (AR and NC) in association with the presence of anomalies in developing oocytes: unexpectedly small in grass goby and irregular disintegrated cytoplasm in grey mullet. The results indicate that the Western Basin is more polluted than the Eastern Basin particularly in the Orbetello where the sewage treatment plant may be a source of aromatic and chlorinated compounds while the Albegna River and the Nassa Canal may be sources of OPs and CBs.

[Benz(a)anthracene and 2,3,7,8-tetrachloro dibenzo(p)dioxin modulate mitogen-stimulated proliferation of lymphocytes]. / Benz(a)antratsen i 2,3,7,8-tetrakhlordibenzo(p)dioksin modiliruiut mitogenstimulirovannuiu proliferatsiiu limfotsitov.

The influence of benzo(a)anthracene (BA) and 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) on functional properties of peripheral blood mononuclear cells (PBC) has been investigated. Incubation of mitogen-stimulated cells in the presence of xenobiotics induced high activity of benzo(a) pyrene-hydroxylase (BH) and suppressed lymphocyte blast transformation. Preincubation of unstimulated PBC with BA and TCDD caused insignificant increase of BH activity. The results show modulated effect of xenobiotics on functional properties of PBC.

Sex differences in hepatic cytochrome P-450 monooxygenase activities in rainbow trout during an annual reproductive cycle.

Hepatic microsomal cytochrome P-450 monooxygenase activities were investigated in rainbow trout during an annual reproductive cycle. The fish were kept in tanks supplied with fresh water at a constant temperature of 10 degrees C. The daily light and darkness cycle was adjusted to follow the natural photoperiod. Sampling was performed once every month for 1 year. Higher benzo(a)pyrene-hydroxylase (or aryl hydrocarbon hydroxylase; AHH), ethoxycoumarin-O-deethylase (ECOD) and ethylmorphine-N-demethylase (END) activities and cytochrome P-450 content were found during the late stage of sexual development in rainbow trout. When monooxygenase activities were expressed on a per cytochrome P-450 basis, sex-dependent differences were observed only for AHH and ECOD activities. It was thus found that sex-dependent variations of END were closely correlated with the total amount of cytochrome P-450. The results indicate that differences exist in hepatic cytochrome P-450 isoenzyme patterns between the sexes in rainbow trout. The similarity of the annual pattern of plasma levels of oestradiol and testosterone to that of sex-dependent differences in the cytochrome P-450 monooxygenases support the contention that sex steroids play a role in regulating the cytochrome P-450 system.

In situ localization and distribution of xenobiotic-activating enzymes and aryl hydrocarbon hydroxylase activity in lungs of untreated rats.

The present investigation was undertaken to more precisely establish where xenobiotics can be oxidatively metabolized and bioactivated within the lung. To accomplish this, antibodies raised against NADPH-cytochrome P-450 reductase (EC 1.6.2.4) and cytochromes P-450 BNF-B, PB-B, and PCN-E (the major forms of cytochrome P-450 induced by beta-naphthoflavone, phenobarbital, and pregnenolone-16 alpha-carbonitrile, respectively) that had been purified to apparent homogeneity from rat liver microsomes were used to determine the localizations and distributions of these enzymes immunohistochemically at the light microscopic level within lungs of untreated rats. Additionally, the intrapulmonary sites at which benzo(alpha)pyrene undergoes hydroxylation were identified in situ by means of fluorescence histochemistry. Immunohistochemical staining for NADPH-cytochrome P-450 reductase and cytochromes P-450 BNF-B, PB-B, and PCN-E was detected in bronchial epithelial cells, both ciliated and nonciliated (Clara) bronchiolar epithelial cells, and type II pneumocytes as well as other cells in the alveolar wall. Results of microfluorometric analyses of the immunofluorescence staining intensities of bronchial epithelial cells, Clara cells, and type II pneumocytes demonstrated further that Clara cells bound the antibodies raised to NADPH-cytochrome P-450 reductase and cytochrome P-450 PB-B to significantly greater extents than did bronchial epithelial cells and type II pneumocytes. Thus, in lungs of untreated rats, Clara cells contain the greatest amounts of these two enzymes. In marked contrast, the antibodies directed against cytochromes P-450 BNF-B and PCN-E were each bound to similar extents by bronchial epithelial cells, Clara cells, and type II pneumocytes. In agreement with immunohistochemical observations on the intrapulmonary localizations of NADPH-cytochrome P-450 reductase and cytochromes P-450 BNF-B, PB-B, and PCN-E in untreated rats, benzo(alpha)pyrene was hydroxylated in situ by bronchial and bronchiolar epithelial cells and alveolar wall cells, especially type II pneumocytes. These immunohistochemical and histochemical findings, thus, demonstrate that bronchial epithelial cells, Clara and ciliated bronchiolar epithelial cells, and type II pneumocytes as well as other alveolar wall cells represent sites for the in vivo oxidative metabolism and bioactivation of xenobiotics in lungs of untreated rats.

[Microsomal monooxygenases of the liver in mice with transplanted tumors]. / Mikrosomnye monooksigenazy pecheni u myshei s perevivaemymi opukholiami.

Hepatoma 22a and Ehrlich's tumor growth were shown to be accompanied by decrease in cytochrome P-450 level in liver of noninbred and C3HA mice, these changes being more pronounced as compared to solid neoplasms. Benzo(a)pyrene-hydroxylase and amidopyrine-N-demethylase activity varied with tumor pattern. It was not changed in cases of hepatoma 22a but decreased in mice bearing Ehrlich's tumor, particularly, in those with the ascitic form. The inhibition analysis using metyrapone and 7,8-benzoflavone identified phenobarbital and methylcholanthrene forms of benzo(a)pyrene-hydroxylase in murine liver; isoform profile was not significantly affected by tumor. Liver microsomal monooxygenases of tumor-bearing mice retained inducibility by 3-methylcholanthrene.

Biomonitoring of oil spill in a boreal archipelago by xenobiotic biotransformation in perch (Perca fluviatilis).

The effect of the accidental oil spill (250 tons) in a boreal archipelago (Gulf of Bothnia, Vaasa, Finland) on xenobiotic metabolism of local perch (Perca fluviatilis) was monitored for 1.5 years. The monooxygenase (benzo[a]pyrene, 7-ethoxycoumarin O-deethylase, 7-ethoxyresorufin O-deethylase) and conjugation (UDPglucuronosyltransferase, glutathione S-transferase) activities of perch liver were determined from control areas and those areas where oil had spilled. Only a slight induction in monooxygenase activities was seen in perch caught near the oil spill 4 months after the accident. The induction of monooxygenase activities detected with the fuel oil in laboratory experiments was, however, clear. After a single dose, it rose rapidly and quickly disappeared. Conjugation enzyme activities were not affected in the laboratory.

Effect of flutamide on hepatic cytosolic methyltrienolone (R1881) binding kinetics and testosterone responsive hepatic drug and steroid metabolism in the adult male rat.

Flutamide was used to investigate the mechanism involved in androgen responsive hepatic microsomal drug and steroid metabolism. We compared the antiandrogenic action of flutamide on the prostate to its effect on testosterone responsive hepatic microsomal benzo[a]pyrene hydroxylase (BPH) and testosterone reductase (TR) activities. Male Wistar rats, castrated as adults, were treated with 5 mumoles.kg-1.day-1 of testosterone enanthate subcutaneously for 10 days. Co-administration of increasing doses of flutamide caused a dose-dependent reduction in prostate to body weight ratios and, in the same animals, caused significant alterations in adult male hepatic microsomal BPH and TR activities. These doses of flutamide did not affect the serum testosterone levels. To test the possibility that the action of flutamide on androgen responsive hepatic microsomal drug and steroid metabolism may be similar to that occurring in the prostate, a tissue which contains an androgen receptor, we also studied the effect of flutamide on the binding kinetics of the high affinity hepatic cytosolic [3H]R1881 binding protein in vivo. Scatchard analysis of [3H]R1881 binding data revealed a reduction in the binding capacity of the hepatic cytosolic androgen binding protein in castrated animals treated with a combination of flutamide and testosterone enanthate at doses capable of maximally altering hepatic microsomal drug and steroid metabolism. No alteration in binding affinity occurred in this treatment group. However, a decreased binding affinity was found when flutamide alone was given. The binding kinetics of the hepatic cytosolic androgen binding protein were not altered in the castrated adult male with or without testosterone treatment. When flutamide was injected daily into the intact adult female rat, no effect was observed on either hepatic microsomal BPH or TR activities. Taken together, these data indicate that flutamide reduces hepatic cytosolic R1881 binding in the adult male rat, and this may explain some of the effects of this antiandrogen on testosterone-sensitive hepatic microsomal drug and steroid metabolism.

Effects of vitamin A and/or thyroidectomy on liver microsomal enzymes and their induction in 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated rats.

Vitamin A and thyroid hormone status have been shown previously to alter the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in rats. In the present study, we have examined the effects of a vitamin A-excess and a vitamin A-deficient diet on thyroid hormone levels, on selected drug-metabolizing enzymes in liver microsomes, and on their inducibility by TCDD in male Sprague-Dawley rats. Except for a slight increase in serum T3 levels, none of these end points was affected by feeding rats the vitamin A-deficient diet. In contrast, excess dietary vitamin A caused a decrease in serum thyroxine (T4) and triiodothyronine (T3) levels, although the levels of T3 remained in the euthyroid range (60-80 ng/dl). The concentration of liver microsomal cytochromes P-450 and b5 and the basal activity of benzo[a]pyrene hydroxylase and 7-ethoxyresorufin O-de-ethylase were unaffected by excess dietary vitamin A. This result is consistent with our previous observation that the basal activity of these enzymes is dependent more on T3 than on T4 levels. Vitamin A excess markedly suppressed the activity of liver microsomal UDP-glucuronosyl transferase toward 1-naphthol. However, no such enzyme suppression was observed in thyroidectomized rats. This suggests that the suppressive effect of vitamin A on UDP-glucuronosyl transferase activity may be dependent on T3. Neither vitamin A nor thyroid status had any major effect on the inducibility of UDP-glucuronosyl transferase and cytochrome P-450-dependent enzyme activities by TCDD. However, vitamin A and TCDD had a nearly additive effect on suppression of serum T4. It is concluded that liver microsomal enzyme induction is not associated with the modulatory effect of vitamin A and thyroid hormones on the toxicity of TCDD.

Effects of Maillard browned egg albumin on drug-metabolizing enzyme systems in the rat.

Adult male Sprague-Dawley rats were fed a purified diet containing 5% Maillard browned egg albumin (EA-B) or browned hydrolysed egg albumin (HEA-B) for 10 wk. Control animals were pair-fed a corresponding isocaloric, isonitrogenous non-browned egg albumin (EA-C) or hydrolysed egg albumin (HEA-C) diet. At the end of 10 wk, the rats were killed and hepatic, small intestinal and colonic microsomes and cytosol fractions were prepared by ultracentrifugation. Animals fed EA-B exhibited significantly (P less than 0.05) increased hepatic benzo[alpha]pyrene hydroxylase activity and significantly (P less than 0.05) decreased colonic aminopyrine N-demethylase activity compared to control (EA-C) animals. HEA-B-fed animals also exhibited a significant (P less than 0.05) decrease in colonic aminopyrine N-demethylase activity compared with HEA-C controls, but no significant differences were detected in hepatic or small intestinal enzyme activities in this group. These data suggest that Maillard browned protein products may modify hepatic and/or colonic drug-metabolizing enzyme system activities, and may thus contribute to alterations in the metabolism of endogenous substrates and of exogenous drugs, precarcinogens and other xenobiotics.

Phenobarbital depression of hepatic microsomal benzo[a]pyrene hydroxylation in rats starved and refed a diet containing menhaden fish oil: substrate and fat level dependency.

The influence of phenobarbital on the activity of hepatic mixed function oxidases responsible for benzo[a]pyrene hydroxylation was studied in rats fed diets containing menhaden fish oil (rich in n-3 fatty acids). Male rats were starved for 2 days and refed diet devoid of fat or containing 0.5, 10, or 20% menhaden oil for 4 days. Phenobarbital increased the apparent Km value as well as Vmax for benzo[a]pyrene hydroxylase in microsomes from rats fed the 20% menhaden oil diet. The increased Km was due to a progressive decrease in benzo[a]pyrene metabolism at the lower substrate concentrations, even in the presence of increased cytochrome P-450 content. The phenobarbital-induced increase in Km and the decreases in benzo[a]pyrene hydroxylation were not observed in rats fed 0.5% menhaden oil or a diet devoid of fat.

Effect of co-administration of interferon inducer, polyriboinosinic acid-polyribocytidylic acid, with SKF 525-A on hepatic drug metabolizing enzymes of rats.

The protective effect of SKF 525-A on the suppression of cytochrome P-450 content and monooxygenase activities by treatment with CoCl2 and polyriboinosinic acid-polyribocytidylic acid [poly(I.C] was compared as a part of studies of suppression of drug metabolizing enzymes by interferon inducers. Induction of heme oxygenase activity by CoCl2 and poly (I.C) was not altered by simultaneous treatment with SKF 525-A. Depression of cytochrome P-450 content and benzphetamine N-demethylase activity by treatment with CoCl2 was prevented by co-treatment with SKF 525-A. This effect was explained by the prevention of release of heme from cytochrome P-450 by forming metabolic intermediate complexes with metabolites of SKF 525-A. On the other hand, poly(I.C) significantly suppressed P-450 content and benzphetamine N-demethylase and benzo [a] pyrene hydroxylase activities, even under simultaneous treatment with SKF 525-A. This inhibition by poly (I.C) was accompanied by weak staining of proteins corresponding to cytochrome P-450 in SDS gel electrophoresis. In addition, the activity of non-heme enzyme, 4-hydroxybiphenyl glucuronyltransferase, was suppressed by treatment with poly (I.C) but not by CoCl2-treatment. These findings strongly suggested that, unlike CoCl2, poly (I.C) suppressed cytochrome P-450 content and monooxygenase activities due to decreased synthesis or increased degradation of the apoprotein of cytochrome P-450 with slight contribution of the induced heme oxygenase.

Effects of organic solvent vehicles on benzo[a]pyrene metabolism in rabbit lung microsomes.

In order to study the metabolism of benzo[a]pyrene (BP), it must be dissolved in an organic solvent vehicle for delivery to the tissue. We studied the effects of five organic solvent vehicles, i.e. dimethyl sulfoxide (DMSO), acetone, methanol, ethanol, and ethyl acetate, on benzo[a]pyrene hydroxylase activity and the BP metabolite profile in rabbit lung microsomes. Fluorescence detection of 3- and 9-OH-BP was used to evaluate benzo[a]pyrene hydroxylase activity, and the BP metabolite profile was obtained by HPLC analysis. All solvent vehicles inhibited benzo[a]pyrene hydroxylase in a dose-dependent manner. When the smallest volume of each solvent (10 microliter/ml reaction mixture) was employed, the resulting enzyme activities as related to solvent type, from highest to lowest, were DMSO greater than or equal to methanol greater than ethanol greater than or equal to acetone greater than ethyl acetate. HPLC analysis of BP metabolites formed in the presence of the five solvent vehicles showed that production of all metabolites was greatest when DMSO was used and that linearity of product formation was retained longer with DMSO. The metabolites produced when DMSO was used as the solvent were BP-9,10-diol, BP-4,5-diol, BP-7,8-diol, BP-1,6-quinone, BP-3,6-quinone and 3-OH-BP. A similar metabolite profile was obtained when reactions were carried out with methanol as the solvent vehicle, although the magnitude of production was less than with DMSO. When acetone was used, there were greater amounts of BP-4,5-diol and BP quinone formation and lesser amounts of 3-OH-BP formed than with DMSO or methanol. When ethanol or ethyl acetate was used as a solvent, BP-9,10-diol and 3-OH-BP were the only metabolites produced. These results indicate that all solvent vehicles studied inhibit benzo[a]pyrene hydroxylase from rabbit lung microsomes in a dose-dependent manner and that the magnitudes and types of metabolites formed are highly dependent upon the specific solvent used as the vehicle. The study also indicates that DMSO is probably the solvent vehicle of choice for study of BP metabolism in rabbit lung microsomes.

A comparison of the effect of two bovine serum albumin preparations on benzo(alpha)pyrene hydroxylase in rat liver and lung microsomes.

One of two commercial bovine serum albumin preparations caused decreases in rat liver and lung microsomal benzo(alpha)pyrene hydroxylase activities when measured by the fluorescence assay. The decreased activities were not due to a decreased recovery of a reaction product, 3-hydroxybenzo (alpha)pyrene, the presence of unmasked fatty acid binding sites or decreased content of cytochrome P450. The decreased enzyme activity may be due to a component present in the preparation. The results indicate that bovine serum albumin preparations should be carefully checked before use in the benzo(alpha)pyrene hydroxylase assay.

The effects of fractionated thermally oxidized corn oil on drug-metabolizing enzyme systems in the rat.

Corn oil samples were heated, with aeration, to 210 degrees C for a total of 5 hr. Both fresh and oxidized samples were urea-fractionated and the individual fractions were administered to male Sprague-Dawley rats by gastric intubation. The effects of urea adducts, adduct-free fractions, non-saponifiable fractions and unfractioned fresh and thermally oxidized oil samples on hepatic, intestinal and colonic drug-metabolizing enzymes were determined. The treatments had no significant effects on hepatic or intestinal drug-metabolizing or mixed-function oxidase activities. There was a significant (P less than 0.05) increase in colonic UDP-glucuronyltransferase activity in rats treated with thermally oxidized corn oil, while the non-saponifiable fraction of the same sample decreased (P less than 0.1) the activity of this enzyme. There was also a significant increase in the activity of colonic benzo[a]pyrene hydroxylase in rats treated with the non-adduct fraction or with urea adducts of the thermally oxidized corn oil. These data suggest the colon as a possible specific site for the alteration of mixed-function oxidase activities by products of thermally oxidized oils.