Effect of lupeol on antioxidants and xenobiotic enzymes in N-Butyl-N-(4-hydroxybutyl) nitrosamine induced bladder carcinogenesis in experimental rats.

OBJECTIVE: Urothelial carcinoma of the bladder is a common malignancy ranked 9th with an estimated 356,600 new cases diagnosed annually worldwide. The study showed the protective effects of Lupeol in N-Butyl-N-(4-hydroxybutyl) nitrosamine induced bladder carcinogenesis in in vivo experimental model. Forty male healthy wistar rats were selected randomly divided into four groups. Group I rats served as healthy control. Group II rats were treated with BBN (150 mg/gavage/twice a week) for 8 weeks. Group III rats were treated with BBN + Lupeol [ Lupeol (50 mg/kg bw/day) treatment was started 1 week prior to the BBN treatment, and it was orally administered for 8 weeks]. Group IV rats were treated with Lupeol alone (50 mg/kg bw/day) for 8 weeks. All the experimental rats were maintained and euthanized at 32nd week. Serum and bladder tissues were collected and examined for biochemical parameters, serum markers and histopathological evaluation. Preventive (BBN + Lupeol) group modulates the activity of antioxidant enzymes such as Superoxide dismutase, Catalase, Reduced glutathione, Glutathione Peroxidase, Thiobarbituric acid reactive substances (TBARS) and drug metabolizing enzymes such as Cytochrome P450, Cytochrome b5, NADPH Cytochrome c reductase, NADPH- Quinone Oxidoreductase 1 and Glutathione-S-transferase when compared to BBN treated rats. Serological markers such as Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) were significantly (P<0.05) decreased in preventive lupeol treated groups. Lupeol supplementation protects BBN induced bladder carcinogenesis in experimental rats by its antioxidant, anti-inflammatory and antiproliferative properties.

Responses of CYP450 dependent system to aliphatic and aromatic hydrocarbons body burden in transplanted mussels from South coast of Portugal.

Mussels Mytilus galloprovincialis were cross-transplanted at South Portugal from a reference site (site 1) to a site more contaminated with hydrocarbon compounds (site 2), and vice versa, in an active biomonitoring (ABM) concept, to assess the biotransformation capacity catalyzed by the mixed function oxygenase (MFO) system. Total alkanes (TAlk), the unresolved complex mixture (UCM), and total polycyclic aromatic hydrocarbons (TPAHs) concentration increased respectively 6, 4.4 and 4.2 fold relatively to control, in mussels transplanted from site 1 to 2. In the cross-transplant, a 48, 57 and 62% depuration of TAlk, UCM and TPAHs concentrations occurred by the end of the 3-4th week. Petrogenic and biogenic (marine and terrigenous) sources of AHs, and petrogenic and pyrolitic (biomass and oil/fuel incomplete combustion) sources of PAHs were detected at both sites. CYP450, CYT b (5) and NADPH-RED in mussels transplanted from site 1 to 2 were induced from day 0 to 28, with a total increase of 35, 32 and 35%, respectively, while biochemical equilibrium to lesser environmental contamination occurs in mussels transplanted from site 2 to 1. A significant relationship between CYP450 and NADPH-RED was found with TPAH, with distinctive behavior at the two sites. MFO system components increase with exposure time at one site and decreases in the other, reflecting an adaptation to distinct environmental hydrocarbon loads. The ABM strategy proved to be useful to understand the environment real impact on the biochemical responses in mussels' local populations. In this study, CYP450 and NADPH-RED are a useful biomarker for hydrocarbon exposure.

Spectral characterization and chiral interactions of plant microsomal cytochrome P450 with metolachlor and herbicide safeners.

The content and spectral characteristics of cytochrome P450 (Cyt P450) and cytochrome b(5) (Cyt b(5)) extracted from shoots of etiolated maize and rice seedlings were studied by using ultraviolet (UV) difference spectrophotometry. The results showed that fenclorim, rac-metolachlor and S-metolachlor may induce the same P450 isoenzyme with lambda(max) at 453 nm, while naphthalic anhydride (NA) induced another one with lambda(max) at 447 nm. The microsomal Cyt P450 and Cyt b(5) content of maize seedlings was higher than that of rice, and the Cyt b(5) content was higher than that of Cyt P450. Maize and rice microsomal Cyt P450 and Cyt b(5) were induced at different levels by the four chemicals, with the order as follows: NA > fenclorim > rac-metolachlor > S-metolachlor with p < 0.05. When induced by NA, fenclorim, rac-metolachlor and S-metolachlor, the maize Cyt P450 content was, respectively, 5.63-, 3.30-, 3.02- and 2.48-fold that of the control, the rice Cyt P450 content was 8.54-, 2.20-, 1.91- and 1.33-fold that of the control, the maize Cyt b(5) content was 9.89-, 5.49-, 4.69- and 3.40-fold that of the control, and the rice Cyt b(5) content was 7.76-, 4.56-, 2.60- and 1.82-fold that of the control. An enantio-difference existed when rac- and S-metolachlor combined with plant Cyt P450. The interaction of microsomal Cyt P450 with S-metolachlor is higher than that with rac-metolachlor, which may be one of the reasons why S-metolachlor is superior at killing weeds compared with rac-metolachlor. These results will help to develop an understanding of the tolerance for and selectivity of rac- and S-metolachlor.

N-nitroso compounds induce changes in carcinogen-metabolizing enzymes.

The bioactivation of N-nitrosoamines and polycyclic aromatic hydrocarbons (PAH) is mediated by the mixed function oxidase system, which includes dimethylnitrosamine N-demethylase I (DMN-dI), arylhydrocarbon hydroxylase (AHH), cytochrome P-450, cytochrome b5 and NADPH-cytochrome c reductase of liver microsomes. The present study shows the influence of N-nitroso compounds on the activities of the above-mentioned enzymes. Single-dose treatment (20 mg/kg body weight) of male mice with ethylbutylnitrosamine, propylbutylnitrosamine, or dibutylnitrosamine: increased (1) the activity of DMN-dI by 108%, 104%, 51%, respectively; (2) the cytochrome P-450 content by 106%, 72%, 51%, respectively; (3) the activity of AHH by 95%, 106%, 80% respectively; (4) the cytochrome b5 content by 164%, 97%, 94% respectively; and (5) decreased the activity of NADPH-cytochrome c reductase by 55%, 50% and 45%, respectively. Methylpropylnitrosamine decreased the activity of DMN-dI by 44% and the P-450 content by 50%. Diphenylnitrosamine also decreased cytochrome P-450 by 54%, AHH activity by 64% but increased the activity of DMN-dI by 42%, the cytochrome b5 content by 159% and NADPH-cytochrome c reductase activity by 57%. It seems from this study that the activity of AHH is dependent on P-450 content but DMN-dI is not since the compounds that increased or decreased the activity of AHH had parallel effects on P-450 content. Also, the extent to which the altered activities of DMN-dI, P-450, AHH, cytochrome b5 and NADPH-cytochrome c reductase depends on the type of alkyl groups linked to the nitroso group.

Modulatory influence of injectable contraceptive steroid medroxyprogesterone acetate on methylcholanthrene-induced carcinogenesis in the uterine cervix of mouse.

Methylcholanthrene (approximately 300 micrograms) plus beeswax-impregnated thread, when placed inside the canal of the uterine cervix of virgin female adult mice for 30, 60 and 90 days produced cervical tumors in 0.0, 10 and 30% of mice, respectively. Employing this experimental cervical carcinogenesis model system, the present study evaluated the modulatory influence of medroxyprogesterone acetate (MPA) on the incidences of precancerous and cancerous lesions in the cervical epithelium as well as on phase I and phase II drug metabolizing enzymes and acid soluble sulfhydryl level in the liver. Intramuscular administration of MPA (50 micrograms every 5th day) to the carcinogen-thread inserted mice for 30, 60 and 90 days produced cervical tumors respectively in 0.0, 13.3 and 60.5% (P less than 0.05) of mice. A significant increase (P less than 0.05) in hyperplasia was also observed in the present study. A significant decrease in cytochrome b5 was found after 30 days.

Modulatory influences of clove (Caryophyllus aromaticus, L) on hepatic detoxification systems and bone marrow genotoxicity in male Swiss albino mice.

Modulatory effects observed due to clove administration (0.5%, 1% and 2% w/w in the diet) to Swiss albino mice for 10, 20 and 30 days in the hepatic levels of cytochrome P-450 (Cyt. P-450), cytochrome b5 (Cyt. b5), aryl hydrocarbon hydroxylase (AHH), glutathione S-transferase (GST), DT-diaphorase (DTD), acid soluble sulfhydryl (SH) content and radiation-induced malondialdehyde (MDA) formation were recorded. Enhanced GST, Cyt. b5 and SH levels were observed in all the treatment groups, excepting those maintained on a 0.5% diet for 10 days which did not show significant increase in the GST and SH levels as compared to their respective controls. Significant reduction in Cyt. P-450 and MDA levels was observed in all groups at 30 days duration. While AHH levels remained unaltered by clove administration, DTD activity was elevated by 1% and 2% clove diets at 30 days duration. An in vivo bone marrow micronucleus assay demonstrated that administration of 0.5% and 2% clove diets for 10 days neither significantly induced micronuclei nor could effectively modulate the 7, 12-dimethylbenz[a]anthracene genotoxicity in mice. The results suggest whole cloves as potential chemopreventive agents.

Effect of arecanut, a masticatory, on hepatic drug metabolizing enzymes -SH content and lipid peroxidation in lactating mothers and their suckling neonates.

The modulation caused by arecanut, a major ingredient of the masticatory substance betel quid, on biotransformation system enzymes, acid soluble sulfhydryl (-SH) content and lipid peroxidation was assessed in lactating mice and their neonates. Following parturition, dams were fed a 1% arecanut diet and F1 mice were nursed by their own mothers during the lactation period of 21 days. Arecanut induced significant increases in the levels of cytochrome b5, cytochrome P-450, glutathione S-transferase and malondialdehyde (MDA) in dams and their pups. However, it decreased the -SH content in lactating mice and F1 progeny; whether the F1 mice were exposed to the translactational dose of arecanut for 21 days or to a similar translactational dose plus a dietary dose of arecanut for additional post weaning period of 21 days, the pattern of changes in the profile of biotransformation system enzymes was essentially similar. The changes elicited by arecanut intake in the levels/activities of enzymes of the biotransformation system, MDA level and -SH content may enhance the susceptibility of neonatal stages of mice to the action of chemical carcinogens.

The effect of repeat administration of GTS-21 on mixed-function oxidase activities in rat.

The effect of repeat administration of GTS-21 on hepatic microsomal enzymes was determined in rats administered the drug at levels of 3, 60 and 300 mg/kg/day for 7 days. Liver weight and cytochrome P450 (CYP) contents were not changed. Cytochrome b5 contents were increased at the mid and high doses of GTS-21, as the contents increased with increasing dose, but were unchanged at the low dose. Five selective activities of CYP isoforms, acetanilide hydroxylase (CYP1A2), tolbutamide hydroxylase (CYP2C6), dextromethorphan O-demethylase (CYP2D1), p-nitrophenol hydroxylase (CYP2E1) and erythromycin N-demethylase (CYP3A) were examined. Enzyme activities were changed only at the highest dose; the activity of CYP1A2 was increased by 71% and the activities of CYP2C6 and CYP2D1 were decreased by 37 and 19%, respectively. At low and mid doses of GTS-21, all activities were unchanged. These data indicate that GTS-21 is not a strong modulator of the mixed-function oxidase system.

Combined effect of propranolol with nifedipine or with diltiazem on rat liver monooxygenase activities.

The effects of two Ca2+ antagonists nifedipine (NF) and diltiazem (DL) and of the nonselective beta-adrenergic blocking agent propranolol (PR) on the hexobarbital (HB) sleeping time and on the activity of some liver drug-metabolizing enzyme systems in male Wistar rats were studied. Two h after single oral administration PR (50 mg/kg) did not change HB sleeping time, while NF (50 mg/kg) and DL (30 mg/kg) prolonged it by 171.2 and 99.6%, respectively. Coadmistration of PR with DL or with NF significantly prolonged HB sleep by 240.7 and 129%, respectively. Only NF increased aniline 4-hidroxylase (AH) activity (by 92%) and the total P-450 content (by 24%). PR and NF increased cytochrome b5 content and this effect was also observed with the combinations PR + NF (by 109%) and PR + DL (by 102%). The NADPH cytochrome P-450 reductase activity was significantly decreased by NF and DL and after their combination with PR. The ethymorphine-N-demethylase (EMND) and amidopyrine-N-demethylase (APND) activities were not changed. The effects of PR, NF and DL administrated alone or in combination on liver oxidative metabolism are considered as possible mechanisms of drug interactions.

Effects of phenobarbital, dietary protein intake, and ewe liveweight on ovulation rate and concentrations of plasma FSH and hepatic microsomal enzymes.

Coopworth ewes were differentially fed from December 1985 to April 1986 to produce two liveweight classes: fat (55-60 kg) and thin (40-45 kg). The ewes were then fed on either high-protein (22%) or low-protein (12%) diets, with or without phenobarbital treatment for 10 days commencing on Day 7 of the oestrous cycle. Phenobarbital treatment caused an increase in ovulation rate that was most pronounced in thin ewes and those on the low-protein diet. Ewe liveweight produced an increase in ovulation rate, but increased dietary protein in the particular formulations used had no effect. Hepatic enzyme concentrations were increased by phenobarbital treatment and, to a lesser extent, by dietary protein intake and ewe liveweight. However, these metabolic changes and the increase in ovulation rate were not accompanied by interpretable changes in the plasma FSH concentrations.

Effect of hexavalent chromium on drug-metabolizing enzymes in male domesticated rabbits.

We studied the effect of chromium on the drug-metabolizing enzymes (DME) in male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The activities of cytochrome P-450 (183%), aniline hydroxylase (ANH, 265%), acetanilide hydroxylase (ACH, 160%), benzphetamine demethylase (BD, 112%), aminopyrine demethylase (AD, 97%), N,N,-dimethyl aniline demethylase (DAD, 72%), and cytochrome-c-reductase (100%) were increased after PB treatment. The activities of cytochrome b5 and N,N,-dimethyl aniline N-oxide (DAO) were, however, decreased 79% and 47%, respectively. Most of the DME remained unaffected after PM treatment except for the increase in ANH (55%), ACH (56%), and BD (16%). Potassium dichromate administered to rabbits at a dose of 8 mg/kg body weight/day for 5 days resulted in an increase in the activities of ANH (108%), BD (76%), AD (25%), and DAD (49%), while that of cytochrome b5 and DAO were inhibited 81 and 77%, respectively. There was no effect on the activities of cytochrome P-450, ACH, and cytochrome-c-reductase. Chromium, administered to PB-pretreated animals decreased the activities of ANH (41%), ACH (35%), BD (34%), AD (30%), DAD (51%), cytochrome-c-reductase (72%), and DAO (62%). Other enzymes remained unaffected. When administered to PM-pretreated animals, the activities of ANH, BD, AD, and DAD increased 34, 69, 24 and 54%, respectively, whereas activities of cytochrome b5 and DAO were decreased 96 and 68%, respectively. All other DME remained unaffected.

Modulatory effect of Areca nut on the action of mace (Myristica fragrans, Houtt) on the hepatic detoxification system in mice.

The present paper reports the modifying potential of areca nut (Areca catechu), an ingredient of the habitual masticatory betel quid, on the induction of the hepatic detoxification system in mice by mace (the aril of nutmeg, Myristica fragrans) a known chemopreventor of chemically induced carcinogenesis. The modulatory effect of areca nut was assessed by determining the levels of enzymes of the hepatic detoxification system, such as glutathione S-transferase (GST), cytochrome b5 and cytochrome P-450, and the content of acid-soluble sulphhydryl (-SH). Mice were fed either control diet or diet containing 0.25, 0.5 or 1% areca nut for 45 days. During the last 10 days the diet was supplemented with 0.5 or 1% mace. At 0.5 and 1% in the diet, areca nut decreased mace-induced increases in hepatic GST and -SH levels and elevated further increases in the levels of cytochrome b5 and cytochrome P-450.

Transmammary modulation of xenobiotic metabolizing enzymes in liver of mouse pups by mace (Myristica fragrans Houtt.).

The present study examines the possible transfer of the active principle(s) of mace (aril of the plant Myristica fragrans) through the transmammary route and its ability to modulate hepatic xenobiotic metabolizing enzymes in the F1 progeny of mice. An aqueous suspension of mace at the dose levels of 0.025 or 0.1 g/animal/day was administered by oral gavage to dams from day 1 of lactation and continued daily for 14 or 21 days. Dams receiving mace treatment and their F1 pups showed significantly elevated hepatic sulfhydryl content, glutathione S-transferase and glutathione reductase activities and cytochrome b5 content. Hepatic cytochrome P450 content decreased in dams (P < 0.05) receiving the lower mace dose for 21 days and the F1 pups (P < 0.001), but increased in dams receiving the higher dose for both time periods (P < 0.001) and the lower dose for 14 days (P < 0.05). Only the 14-day-old pups of dams receiving either mace dose showed significantly elevated (P < 0.001) levels of hepatic glutathione peroxidase.

Toxico-kinetics, recovery efficiency and microsomal changes following administration of deltamethrin to black Bengal goats.

A study of the toxico-kinetics, recovery percentage from different substrates, cytotoxicity and role of cytochrome P450 and b5 of liver microsome in the metabolism of deltamethrin were carried out in female black Bengal goat. The ALD50 value of deltamethrin in goat by intravenous route lies between 0.2 and 0.6 mg kg-1. Intravenous disposition kinetics using a dose of 0.2 mg kg-1 showed that the maximum blood concentration of deltamethrin was recorded at 0.5 min, followed by rapid decline, and a minimum concentration was detected at 6 min after administration. The following values were obtained: Vdarea 0.148 (+/- 0.02) litre kg-1; t1/2 (alpha) 0.22 (+/- 0.02) min; t1/2 (beta) 2.17 (+/- 0.37) min; Kel 1.05 (+/- 0.24) min-1; AUC 4.30 (+/- 0.45) micrograms min ml-1; ClB 0.05 (+/- 0.006) litre kg-1 min-1; T-B 1.93 (+/- 0.58); fc 0.40 (+/- 0.05). After 10 min, liver retained the maximum residue, and heart, adrenal gland, kidney, spleen, fat and brain also held the insecticide; liver, fat, heart and spleen retained residue after 30 min, and bone, liver and fat retained residue after 60 min of intravenous administration. Oral absorption of deltamethrin was poor and inconsistent, and approximately 65% of administered dose was recovered from faeces and gastrointestinal contents. The excretion of deltamethrin through urine was meagre, and only 0.01 and 0.013% of the administered dose was recovered after 3 and 5 days of oral administration respectively. All the tissues retained the residue after 3 days; while fat, rumen, reticulum, omasum, abomasum, large and small intestine and bone retained the residue after 5 days of oral administration; and the percentage recoveries were 1.73 and 0.027 respectively. Deltamethrin reduced the level of cytochrome P450 content of liver microsomal pellet of goat after 5 days of oral administration. Histopathological examination of liver, kidney, heart, spleen brain and lung sections of treated goats did not reveal any pathological changes.

Changes in rat liver monooxygenase activities after administration of atenolol, nifedipine and diltiazem alone and in combination.

The effects of the Ca2+ antagonists nifedipine (NF) and diltiazem (DL) and of the cardioselective beta 1-adrenergic blocking agent atenolol (AT) on the hexobarbital (HB) sleeping time and on the activity of some liver drug-metabolizing enzyme systems in male Wistar rats were studied. Two hours after single oral administration, atenolol (150 mg/kg) did not change hexobarbital sleeping time, while nifedipine (50 mg/kg) and diltiazem (30 mg/kg) prolonged it by 171.2 and 99.6%, respectively. Coadministration of atenolol with diltiazem or with nifedipine significantly prolonged hexobarbital sleep by 205 and 283%, respectively. Administered alone, atenolol decreased the ethylmorphine-N-demethylase (EMND) activity, but the amidopyrine-N-demethylase (APND) activity was not changed in any of the treated groups. Atenolol and nifedipine significantly increased aniline-4-hydroxylase (AH) activity and this effect was also observed with the combinations AT + NF and AT + DL. The NADPH cytochrome P-450 reductase activity was significantly decreased by nifedipine and diltiazem. Only nifedipine increased the total content of cytochrome P-450 (by 23.8%). Atenolol and diltiazem tended to increase the content of cytochrome b5 which was increased by nifedipine by 97.6%. The same effect was observed with the combinations AT + NF and AT + DL. The results suggest that NF, AT + NF and AT + DL produced the manifested changes in hepatic oxidative metabolism. The decreased EMND activity by atenolol, however, and the prolongation of hexobarbital sleeping time by nifedipine, diltiazem and their coadministration with atenolol did not correlate with enhanced microsomal P-450 and b5 content.

Effect of country liquor (Indian alcoholic beverage) on carcinogen activating and detoxifying enzymes.

The levels of some important drug activating and detoxyfying enzymes were estimated in the livers of Swiss mice treated with a local brand of country liquor. Following liquor ingestion in male mice elevated levels of hepatic cytochrome P-450 were observed, while female mice did not show this. Cytochrome b5 levels remained unchanged. Similarly in male mice, increase in hepatic reduced glutathione levels were obtained while in female mice, decrease in this was observed. The activity of glutathione S-transferase was not changed. It is suggested that the increases in cytochrome P-450 and in hepatic reduced glutathione may be important determinants in carcinogenecity of the country liquors.

[Effect of long-term administration of undevit and its combination with cordiamine on hydroxylation, glucuronidation and glutathione conjugation systems and lipid peroxidation in rat liver]. / Vliianie dlitelnogo vvedeniia undevita i ego kombinatsii s kordiaminomna gidroksiliruiushchuiu, gliukuro-, glutationkoníugiruiushchuiu sistemy i perekisnoe okislenie lipidov pecheni intaktnykh krys.

Increase of N-demethylase and antioxidant activities and decrease of amount of hydroperoxides were observed in liver of rats after intragastric administration of Undevit (1/8 dragee/rats/day, 5 times a week during 2 months). Combination of Undevit with Cordiamin (5 mg/rat/day) resulted in augmentation of cytochromes P-450 and b5 content and activities of their reductases, velocity of amidopyrine and ethylmorphine N-demethylation and oxidation of HADPH. Activities of UDP-glucuronyltransferase, glutathionetransferase and hydrophobity of microsomal membranes were also increased. Antioxidant activity was increased and amount of hydroperoxides in liver microsomes and homogenates and in plasma was decreased in greater degree after administration of combination two compounds than after administration of Undevit alone.

Sheep adrenal cytochrome b5: active as a monomer or a tetramer in vivo?

Cytochrome b5 (cyt b5) is an ubiquitous hemoprotein also associated with microsomal cytochromes P450. It has been reported that cyt b5 influences cytochrome P450-dependent catalyses through electron transport as well as direct protein-protein interactions. To investigate the influence of cyt b5 on ovine adrenal steroidogenesis, we isolated and characterized cyt b5 from ovine liver. The molecular mass of the purified protein was 15,260 as determined by electrospray mass spectrometry. SDS-Polyacrylamide gel electrophoresis, even after stringent detergent and mercaptoethanol pretreatment, indicated multimeric forms of the protein, the most prominent being the tetramer (+/-60 kDa) with minor bands corresponding to the monomer (+/-16 kDa) and dimer (+/-30 kDa). Trypsin treatment of cyt b5 resulted in a truncated enzyme with a molecular mass of +/-10 kDa. The aggregation of cytochrome b5 was abolished by the tryptic removal of the membrane binding region. In Western blot analyses antibodies against the truncated protein recognised only this low molecular mass form and not the full length cyt b5, or any of the higher molecular complexes, showing the involvement of the membrane binding domain of the protein, not only in aggregation, but also in the quaternary structure which determines epitope presentation for antibody production. Immunoblot analyses of sheep adrenal microsomes with the anti-truncated cyt b5 antibody were also negative. Immunoblot analyses and immunocytochemistry of adrenal tissue with antibodies against the full length cyt b5 indicated that the tetrameric form of the protein was in all probability the dominant specie in vivo.

The effect of subacute administration of a neem pesticide on rat metabolic enzymes.

Acute toxicity of a neem pesticide (Vepacide-Tech) was studied in male Wistar rats by oral (single) intubation for 7 days. Vepacide was found to be moderately toxic to rat based on LD50 value. Subacute toxicity of Vepacide-Tech was also studied in male rats by oral (multiple) intubation of low (80 mg Kg-1 day-1), medium (160 mg Kg-1 day-1) and high dose (320 mg Kg-1 day-1) for 90 days. High dose caused a significant decrease in Cytochrome P-450 (Cyt. P-450) concentration at 45 and 90 days and the medium dose caused same effect at 90th day in liver and lung. Kidney showed similar effect at 90 days by the three doses. Cytochrome b5 (Cyt. b5) concentration was significantly decreased in liver, lung and kidney at 45 and 90 days at medium and high doses. Brain Cyt.b5 concentration was decreased on 90th day at high dose. Cytochrome P-450 reductase (Cyt.P-450 reductase) concentration was decreased significantly in liver and brain at 45 and 90 days, respectively at medium and high doses. The withdrawal study (28 days) has shown significant recovery. These results demonstrate that low levels exposure of Vepacide may have significant effect on the xenobiotic detoxification mechanism of different tissues of rat.

Effect of side-stream cigarette smoke on the hepatic cytochrome P450.

The effect of inhalation of side-stream cigarette smoke on the hepatic microsomal cytochrome P450 was investigated Rats were placed in a chamber of 0.1 m3 in volume, in which cigarettes were burned at the rate of 1, 3, or 5 cigarettes per h, 8 h/day for 5 days. Cytochrome P450 and NADPH-cytochrome c reductase showed no significant changes; however, cytochrome b5 increased significantly. On the other hand, the activity of aryl hydrocarbon hydroxylase (AHH) decreased in the rats treated with a high concentration of cigarette smoke. In order to study the changes of isoforms of cytochrome P450, western blot analyses were performed. The inductions of three kinds of isoforms, cytochromes P450IA1, IA2, and IIB1, were demonstrated immunochemically. However, there were disagreements between the results of the western blot analyses and the measurements of total cytochrome P450 content and AHH activity.