RESUMO
A novel finding that genomic restriction fragments of symbiotic nitrogen fixer S. meliloti hybridized with nifM gene probe of the free-living diazotroph Klebsiella pneumoniae is reported. When SmaI endonuclease was used to digest S. meliloti DNA, a unique hybridizing band was obtained.
Assuntos
Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/genética , Oxirredutases/genética , Sinorhizobium meliloti/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Hibridização de Ácido NucleicoRESUMO
The nasal route is widely used for the administration of drugs for both topical and systemic action. At an early stage in drug discovery and during the development process, it is essential to gain a thorough insight of the nasal absorption potential, metabolism and toxicity of the active compound and the components of the drug formulation. Human nasal epithelial cell cultures may provide a reliable screening tool for pharmaco-toxicological assessment of potential nasal drug formulations. The aim of this review is to give an overview of the information relevant for the development of a human nasal epithelial cell culture model useful during drug discovery and development. A primary goal in the development of in vitro cell culture systems is to maintain differentiated morphology and biochemical features, resembling the original tissue as closely as possible. The potential and limitations of the existing in vitro human nasal models are summarized. The following topics related to cell culture methodology are discussed: (i) primary cultures versus cell lines; (ii) cell-support substrate; (iii) medium and medium supplements; and (iv) the air-liquid interface model versus liquid-liquid. Several considerations with respect to the use of in vitro systems for pharmaceutical applications (transport, metabolism, assessment of ciliary toxicity) are also discussed.
Assuntos
Desenho de Fármacos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Mucosa Nasal/citologia , Mucosa Nasal/efeitos dos fármacos , Administração Intranasal , Animais , Células Cultivadas , Cílios/efeitos dos fármacos , Cílios/fisiologia , Sistemas de Liberação de Medicamentos , Humanos , Mucosa Nasal/metabolismo , Preparações Farmacêuticas/administração & dosagemRESUMO
PURPOSE: Explore the usefulness of a perfusion system in order to establish human nasal epithelial cell cultures suitable for long-term in vitro ciliary beat frequency (CBF) and cilio-toxicity studies. METHODS: The cells were obtained by protease digestion of nasal biopsy material. The cells were plated at a density of 0.8-1 x 10(6)/cm2 on Vitrogen-coated polyethylene terephthalate membranes, and cultured under submerged conditions in a CO2 incubator or in a perfusion system (initiated on days 8-9 after plating). The CBF was determined at 24.1 +/- 0.8 degrees C by a computerized microscope photometry system. The morphology of the cultured cells was characterized by transmission electron microscopy (TEM). RESULTS: Under CO2 incubator culture conditions, stable ciliary activity was expressed and maintained from day 2 to day 24. Under perfusion system culture conditions, the CBF (mean+/-S.D., n = 4) amounted to 8.4 +/- 0.9 and 8.8 +/- 0.4 Hz on days 7 and 14, respectively. These values were lower as compared to the corresponding CBF obtained in the CO2 incubator cultures (9.5 +/- 0.6 and 9.9 +/- 1.0 Hz, respectively). Reference cilio-stimulatory (glycocholate) and cilio-inhibitory (chlorocresol) compounds were used to assess CBF reactivity. In the CO2 incubator and 7- and 14-days perfusion system cultures, glycocholate (0.5%) showed a reversible cilio-stimulatory effect of 23, 26 and 21%, respectively, while chlorocresol (0.005%) exerted a reversible cilio-inhibitory effect of 36, 40 and 36%, respectively. TEM revealed polarized cuboidal to columnar epithelial morphology, with well-differentiated ciliated cells under CO2 and perfusion system conditions (up to day 23). CONCLUSION: Culturing human nasal epithelial cells on Vitrogen-coated polyethylene terephthalate membranes in submerged conditions in a CO2 incubator and in a perfusion system offers the possibility for long-term preservation (up to 22-24 days) of stable and reactive CBF in vitro.
Assuntos
Cílios/fisiologia , Cultura em Câmaras de Difusão/métodos , Células Epiteliais/fisiologia , Mucosa Nasal/fisiologia , Animais , Dióxido de Carbono/farmacologia , Células Cultivadas , Cílios/efeitos dos fármacos , Cresóis/farmacologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/ultraestrutura , Ácido Glicocólico/farmacologia , Humanos , Microscopia Eletrônica de Transmissão/métodos , Depuração Mucociliar/efeitos dos fármacos , Depuração Mucociliar/fisiologia , Mucosa Nasal/efeitos dos fármacos , Mucosa Nasal/ultraestrutura , Polietilenotereftalatos/administração & dosagem , Polietilenotereftalatos/farmacocinéticaRESUMO
Paracetamol (acetaminophen, APAP) liver and kidney cytotoxicity is associated with bioactivation by P450 and/or prostaglandin H synthetase (PGHS) to a reactive metabolite, which depletes GSH, covalently binds to proteins, and leads to oxidative stress. Although APAP may also damage the lung, little is known about the mechanism by which this occurs. We studied the in vitro 24-hr-old type II pneumocytes. A time- and concentration-dependent decrease in intracellular GSH occurred in freshly isolated type II pneumocytes and alveolar macrophages exposed to subtoxic (= 1 mM) APAP concentrations. In 24-hr-old type II pneumocytes, there were no changes in intracellular GSH concentration after APAP exposure. Potassium ethyl xanthate (a P450 inhibitor) and indomethacin (a PGHS inhibitor) significantly decreased APAP-induced GSH depletion in freshly isolated type II pneumocytes and alveolar macrophages, suggesting that P450 and/or PGHS are involved in APAP bioactivation in these cells.
Assuntos
Acetaminofen/toxicidade , Pulmão/efeitos dos fármacos , Macrófagos Alveolares/efeitos dos fármacos , Analgésicos não Narcóticos/farmacologia , Animais , Inibidores das Enzimas do Citocromo P-450 , Relação Dose-Resposta a Droga , Interações Medicamentosas , Inibidores Enzimáticos/farmacologia , Glutationa/metabolismo , Técnicas In Vitro , Pulmão/citologia , Masculino , Prostaglandina-Endoperóxido Sintases/efeitos dos fármacos , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , Ratos WistarRESUMO
It has been shown that 5,7,3',4'-tetrahydroxy-3-O-methylflavone (3-MQ) exhibits antipicornaviral activity. In order to explore the potential of 3-MQ as an antirhinoviral compound for nasal application, the effect of 3-MQ on the ciliary beat frequency (CBF) of human nasal epithelial cells was studied in vitro in the absence or presence of solubility/absorption enhancers (hydroxypropyl-beta-cyclodextrin (HP-beta-CD) or polysorbate 80). Nasal epithelial cells were obtained by protease digestion of surgical specimens of human nasal polyps, and used at confluency. The effect of 3-MQ (2, 10, and 20 microg/ml), HP-beta-CD (1, 3, and 10% (w/v)), polysorbate 80 (0.1, 0.3, and 1% (w/v)), and of the combination of 3-MQ with 3% HP-beta-CD or 1% polysorbate 80, on the CBF was determined by computerized microscope photometry 15 min after incubation with the test compounds; recovery was determined 35 min after rinsing. HP-beta-CD at 1 and 3% did not affect CBF; a reversible decrease (by 37%) was observed at 10%. Polysorbate 80 caused a reversible cilio-inhibitory effect of 40, 53, and 49% at 0.1, 0.3, and 1%, respectively. At 2 and 10 microg/ml, 3-MQ showed a reversible cilio-stimulatory effect of 18 and 14%, respectively. Combined with 3% HP-beta-CD, the reversible cilio-stimulatory effect of 2 microg/ml 3-MQ was preserved, while 10 and 20 microg/ml 3-MQ did not affect the CBF. The combination of polysorbate 80 (1%) and 3-MQ decreased the CBF, which could be attributed to the presence of polysorbate 80. In conclusion, no ciliotoxic effect could be observed for 3-MQ (up to 20 microg/ml) in the absence or presence of HP-beta-CD (3%). The potential of this combination as an antirhinoviral formulation for nasal application will be further explored.
Assuntos
Antivirais/efeitos adversos , Mucosa Nasal/efeitos dos fármacos , Mucosa Nasal/virologia , Quercetina/efeitos adversos , Administração Intranasal , Análise de Variância , Antivirais/química , Antivirais/farmacologia , Células Cultivadas , Cílios/efeitos dos fármacos , Cílios/fisiologia , Cílios/virologia , Humanos , Mucosa Nasal/fisiologia , Quercetina/análogos & derivados , Quercetina/farmacologia , Rhinovirus/efeitos dos fármacos , Rhinovirus/fisiologiaRESUMO
The influence of long-term nifedipine administration on the antinociceptive activity of acetaminophen on hexobarbital sleeping time and liver monooxygenase and synthetase activities was studied in male albino mice. Nifedipine was administered orally at a dose of 25 mg/kg daily for 14 and 21 days. The nociceptive response was determined by the acetic acid writhing test. There was no significant difference in the antinociceptive effect of acetaminophen after treatment with nifedipine for 14 days. Nifedipine caused enzyme induction, which was demonstrated by shortened hexobarbital sleeping time, enhanced ethylmorphine-N-demethylase (EMND), aniline-4-hydroxylase (AH), ethoxycoumarine-O-deethylase (ECOD), UDP-glucuronyl transferase (UDPGT), glutathione-S-transferase (GST) and NADPH-cytochrome c reductase activity and increased content of cytochrome P450 and cytochrome b5. It is assumed that this effect of nifedipine on acetaminophen analgesia is associated with the changes (acceleration) in acetaminophen metabolism in the liver after repeated administration of the drug.
Assuntos
Acetaminofen/farmacologia , Analgésicos não Narcóticos/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Nifedipino/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/administração & dosagem , Sistema Enzimático do Citocromo P-450/metabolismo , Citocromos b5/metabolismo , Interações Medicamentosas , Hexobarbital , Hipnóticos e Sedativos , Masculino , Camundongos , Nifedipino/administração & dosagem , Sono/efeitos dos fármacos , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/enzimologia , Frações Subcelulares/metabolismoRESUMO
The influence of the calcium channel blockers (CCBs) nifedipine, verapamil and diltiazem, and the calmodulin antagonist trifluoperazine on the antinociceptive activity of acetaminophen was studied in male albino mice. The nociceptive response was determined by the acetic acid writhing test. Nifedipine (50 or 20 mg/kg), verapamil (20 mg/kg), diltiazem (70 mg/kg) and trifluoperazine (3 mg/kg) were administered orally alone or 1 h before acetaminophen (100 mg/kg). Nifedipine (50 mg/kg), verapamil, diltiazem and trifluoperazine administered alone demonstrated significant antinociceptive effects compared to controls. Nifedipine, verapamil, diltiazem and trifluoperazine applied 1 h before acetaminophen potentiated its antinociceptive activity, which was strongest in mice injected with verapamil and nifedipine (20 mg/kg). It was established that 1 h after nifedipine (50 mg/kg) treatment, cytochrome P450 content, NADPH cytochrome c reductase and ethylmorphine-N-demethylase (EMND) activities were increased in the liver microsomes. Verapamil, diltiazem and trifluoperazine did not change the drug metabolizing enzymes studied. It is assumed that their effect on acetaminophen analgesia is not associated with the changes in acetaminophen oxidative metabolism in the liver.
Assuntos
Acetaminofen/farmacologia , Analgésicos não Narcóticos/farmacologia , Diltiazem/farmacologia , Nifedipino/farmacologia , Trifluoperazina/farmacologia , Verapamil/farmacologia , Analgésicos/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Fracionamento Celular , Antagonistas de Dopamina/farmacologia , Sinergismo Farmacológico , Fígado/enzimologia , Masculino , Camundongos , Medição da DorRESUMO
The accumulation of basic drugs (cationic amphiphilic), such as beta-adrenergic antagonists, by pulmonary tissue is well known. Ring hydroxylation of nonselective beta-adrenergic blocking agent propranolol is mediated mainly by cytochrome P450 (CYP) 2D6 and N-desisopropylation by CYP1A2 in human and rat liver microsomes. In this study, the repeated administration of propranolol resulted in a marked inhibition of hepatic metabolism and an increase in its systemic availability, due to covalent binding of reactive metabolites (formed from 4-OH-propranolol) to liver microsomal P4502D enzymes. The absence of CYP1A2 and the presence of CYP2D in the lung suggest a different pulmonary metabolism of propranolol in comparison with those in the liver. In this study, we investigated its effects in vivo on some xenobiotic-metabolizing enzymes in rat type II pneumocytes (RTII) and rat alveolar macrophages (RAM). Twenty hours after the last multiple (7 days) oral administration, propranolol (100 mg/kg b.w.) decreased NADPH cytochrome c reductase activity and cytochrome P-450-dependent dealkylation of 7-benzyloxyresorufin (BROD) (CYP1A1, 2A1, 3A1) and 7-ethoxyresorufin (EROD) (CYP1A1) in RTII, while glutathione-S-transferase (GST), DT-diaphorase (QR), gamma-glutamyl transferase (gamma-GT) activities, intracellular reduced glutathione level and dealkylation of 7-pentoxyresorufin (PROD) (CYP2B1) were not changed. It was found that propranolol significantly increased NADPH cytochrome c reductase and BROD activities in RAM. The results suggest a different susceptibility of RTII and RAM to propranolol and its contrary effects on lung xenobiotic-metabolizing enzyme activities in both types of cells.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Sistema Enzimático do Citocromo P-450/metabolismo , Pulmão/enzimologia , Macrófagos Alveolares/enzimologia , Propranolol/farmacologia , Xenobióticos/farmacologia , Antagonistas Adrenérgicos beta/metabolismo , Animais , Células Cultivadas , Pulmão/citologia , Pulmão/efeitos dos fármacos , Macrófagos Alveolares/efeitos dos fármacos , Masculino , Propranolol/metabolismo , Ratos , Ratos Wistar , Xenobióticos/metabolismoRESUMO
Propranolol is a lipophilic nonselective beta blocker mainly eliminated via the liver. The specific architectural arrangement of the mammalian lung favors the filtration of so-called pneumophilic drugs out of the blood and retention within the tissue, as shown in particular for amphetamine, amiodarone, imipramine, chlorpromazine, propranolol and local anesthetics. In the current study we tested in vitro the susceptibility of freshly isolated rat type II pneumocytes (RTII), rat alveolar macrophages (RAM), human alveolar macrophages (HAM) and A549 human lung adenocarcinoma cell line (A549) to propranolol (0.001-1 mM). Cytotoxicity was evaluated by changes in membrane integrity (lactate dehydrogenase [LDH] assay) and mitochondrial metabolic activity (reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) after 3-h and 20-h incubation with propranolol. In all tested lung cells, propranolol caused concentration-dependent decreases of MTT reduction and LDH retention in the fraction of attached cells, which was associated with an increase of LDH activity in the medium and in the fraction of non-attached cells. After 3-h incubation, the reduction of MTT was significantly decreased compared with control at > or = 1 x 10(-4) M in HAM, at > or = 5 x 10(-4) M in A549 and significantly decreased of LDH retention in the fraction of attached cells in HAM and in A549 at > or = 5 x 10(-4) M. After 20-h incubation the reduction of MTT was significantly decreased compared with control at > or = 1 x 10(-6) M in RAM, at > or = 5 x 10(-5) M in RTII and HAM and > or = 5 x 10(-4) M in A549. Propranolol caused a significant decrease of LDH retention in the fraction of attached cells (> or = 5 x 10(-5) M, RAM and RTII; > or = 5 x 10(-4) M, HAM and A549). The cytotoxic effect of propranolol in HAM and A549 was more pronounced after prolongation of incubation time (from 3 h to 20 h). These results showed that rat and human lung cells were sensitive to propranolol concentration < or = 1 mM in vitro. We suppose that the damaging action of propranolol on the lungs might be mediated by physicochemical properties of moiety and its pulmonary metabolites.
Assuntos
Antagonistas Adrenérgicos beta/efeitos adversos , Pulmão/efeitos dos fármacos , Propranolol/efeitos adversos , Antagonistas Adrenérgicos beta/metabolismo , Animais , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Humanos , Técnicas In Vitro , Pulmão/metabolismo , Macrófagos Alveolares/efeitos dos fármacos , Macrófagos Alveolares/metabolismo , Masculino , Propranolol/metabolismo , Ratos , Ratos Wistar , Fatores de TempoRESUMO
The influence of rifampicin on the toxicity, analgesic effect and pharmacokinetics of acetaminophen was studied in male albino mice. Repeated administration of rifampicin (50 mg/kg i.p. daily for 6 days) shortened hexobarbital sleeping time and increased liver weight, microsomal cytochrome P-450 and heme contents, NADPH-cytochrome c reductase and ethylmorphine-N-demethylase activities. Aniline hydroxylase activity was decreased and glucuronidation of p-nitrophenol was unaffected. Rifampicin pretreatment changed neither the LD50 of acetaminophen nor the hepatic glutathione level nor the glutathione depletion provoked by the toxic dose of acetaminophen (737 mg/kg p.o.). This suggests that rifampicin has no influence on the amount of acetaminophen toxic metabolites formed in the liver. Rifampicin decreased the acetaminophen analgesic effect in mice. Rifampicin decreased the Cmax, the half-time, the MRT and the AUC of acetaminophen and accelerated its clearance. The plasma concentration of acetaminophen glucuronide and acetaminophen sulfate was increased. It is assumed that the most probable mechanism by which rifampicin decreases acetaminophen analgesia is the accelerated acetaminophen elimination.
Assuntos
Acetaminofen/farmacologia , Acetaminofen/toxicidade , Rifampina/farmacologia , Acetaminofen/farmacocinética , Animais , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/metabolismo , Interações Medicamentosas , Glutationa/metabolismo , Heme/metabolismo , Dose Letal Mediana , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Oxigenases de Função Mista/efeitos dos fármacos , Oxigenases de Função Mista/metabolismo , NADPH-Ferri-Hemoproteína Redutase/efeitos dos fármacos , NADPH-Ferri-Hemoproteína Redutase/metabolismoRESUMO
A decrease in the persistence characteristics of staphylococci under the influence of microclimate in a spelean pit has been demonstrated under experimental conditions. Clinical investigations have confirmed the capacity of speleotherapy to decrease the microbial contamination of the upper respiratory tract and to inhibit the persistence properties of staphylococcal microflora in children with respiratory allergosis, which seems to be the basis of the positive effect achieved by treatment with microclimate in a spelean pit.
Assuntos
Portador Sadio/microbiologia , Microclima , Modalidades de Fisioterapia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/patogenicidade , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Hipersensibilidade Respiratória/microbiologia , Hipersensibilidade Respiratória/reabilitação , Staphylococcus aureus/isolamento & purificação , Fatores de TempoRESUMO
This is a retrospective study on the dynamics of inborn malformations in University Hospital of Obstetrics and Gynaecology 'Maichin Dom', Sofia for a five-years-long period of time (1992-1996). The results show that the rate of inborn anomalies in the discussed period of time remains approximately the same, while there is an increase of the relative part of heavy and life-threatening malformations. They cause death of nearly half of term infants who die in the neonatal period. These facts lead to the conclusion that to decrease perinatal and neonatal mortality, early and exact prenatal diagnosis of inborn malformations is absolutely necessary.
Assuntos
Anormalidades Congênitas/epidemiologia , Peso ao Nascer , Bulgária/epidemiologia , Causas de Morte , Maternidades/estatística & dados numéricos , Hospitais Estaduais/estatística & dados numéricos , Hospitais Universitários/estatística & dados numéricos , Humanos , Incidência , Mortalidade Infantil , Recém-Nascido , Estudos Retrospectivos , Estatísticas não ParamétricasRESUMO
The effect of potassium ethylxanthogenate (PEX) on the toxicity and the analgesic effect of acetaminophen (AAP) were investigated on male albino mice. PEX in a dose of 80 mg/kg body weight, administered subcutaneously or orally one hour before AAP, or simultaneously with it, induces prolongation of the survival of the experimental animals and increases LD50 of AAP. The protective effect of PEX (s.c. and p.o.) is more pronounced when this agent is introduced one hour before AAP (i.p. and p.o.), compared with the simultaneous administration, and when it is applied orally, compared with the subcutaneous administration. The average lethal dose of the combination (AAP p.o. + PEX p.o. 1 hour previously) increases 2.57 times after observation for 7 days, compared with that of AAP. Although it does not possess its own analgesic effect, PEX potentiates the analgesic effect of AAP (which is more pronounced for the low AAP doses) and reduces its average effective dose. After 14-day administration, AAP potentiates its own analgesic effect in the lower doses. The potentiating effect of PEX on the analgesic effect of AAP is similar on the first and on the 14th day of the treatment. The principal mechanism through which PEX decreases the toxicity and potentiates the analgesic effect of AAP is assumed to be the inhibition of its metabolism by inhibition of the cytochrome P-450-linked monooxygenases, not ruling out the possibility of a certain effect on the AAP absorption.
Assuntos
Acetaminofen/farmacologia , Tionas/farmacologia , Acetaminofen/toxicidade , Analgésicos , Animais , Inibidores das Enzimas do Citocromo P-450 , Dose Letal Mediana , Masculino , Camundongos , Oxigenases de Função Mista/antagonistas & inibidoresRESUMO
The effects of potassium ethylxanthogenate (PEX), acetaminophen (AAP) and their combination on the activity of serum transaminases, liver glutathione level and the activity of some drug metabolizing enzyme systems in male albino mice are studied. PEX (80 mg/kg p. o.), applied one hour before AAP (737.5 mg/kg p. o.) or simultaneously with it, prevents the AAP-induced rise in transaminases. PEX reduces significantly the AAP-induced depletion of the liver glutathione. Eighteen hours after the administration of a hepatotoxic dose of AAP, there is a statistically significant decrease of the activity of aniline hydroxylase, ethylmorphine demethylase, uridine diphosphoglucuronyl transferase, glutathione-S-transferase, NADPH-cytochrome-c-reductase, the P-450 content and a 5-fold increase of TBA-reactive products. PEX, introduced one hour before AAP or simultaneously with it, prevents these changes. The basic mechanism through which PEX reduces the liver toxicity of AAP is assumed to be the decrease in the amount of toxic metabolite formed.
Assuntos
Acetaminofen/toxicidade , Doença Hepática Induzida por Substâncias e Drogas/fisiopatologia , Tionas/farmacologia , Alanina Transaminase/sangue , Animais , Aspartato Aminotransferases/sangue , Glutationa/metabolismo , Fígado/metabolismo , Masculino , Camundongos , Oxigenases de Função Mista/metabolismoRESUMO
Because of the evidence for the involvement of xenobiotic bioactivation in pulmonary toxicity and carcinogenesis, it is important to improve our understanding of the xenobiotic-metabolizing enzymes in isolated and cultured specific pulmonary cell populations. Some phase I and phase II xenobiotic-metabolizing enzyme activities, reduced glutathione (GSH), and gamma-glutamyl transferase (gamma-GT) were studied in rat type II pneumocytes and alveolar macrophages cultured for up to 48 h and 3 h, respectively. In type II pneumocytes, 7-ethoxyresorufin activity was not detected. 7-Benzyloxyresorufin (BROD) and 7-pentoxyresorufin (PROD) O-dealkylation decreased at 24 h by 84 and 82%, respectively, and continued to decline over the next 24 h with no measurable PROD at 48 h. The activity of NADPH- and NADH-cytochrome c reductase at 48 h decreased by 31 and 67%, respectively. GST activity decreased by 25 and 42% at 24 and 48 h, respectively. A transient increase in DT-diaphorase activity was observed at 24 h (by 55%). GSH content and gamma-GT activity increased significantly with time in culture. In freshly isolated alveolar macrophages, BROD activity was the only cytochrome P450-dependent alkoxyresorufin-O-dealkylase activity measured. BROD activity decreased by 38% in 3-h-attached macrophages. There were no changes in NADPH- and NADH-cytochrome c reductase, GST, and DT-diaphorase. An increase of GSH (by 24%) was observed in attached macrophages. In conclusion, type II pneumocytes and to a lesser extent alveolar macrophages in primary cultures undergo changes in biotransformation-related enzyme activities and intracellular GSH level that may affect xenobiotic toxicity at different times in culture.
Assuntos
Glutationa Transferase/metabolismo , Pulmão/enzimologia , Macrófagos Alveolares/enzimologia , Xenobióticos/metabolismo , gama-Glutamiltransferase/metabolismo , Animais , Células Cultivadas , Pulmão/citologia , Masculino , Ratos , Ratos WistarRESUMO
The hepatotoxicity of acetaminophen overdose depends on the metabolic activation to a toxic reactive metabolite by the hepatic mixed function oxidases. There is evidence that an increase in cytosolic Ca2+ is involved in acetaminophen hepatotoxicity. The effects of the Ca2+-antagonists nifedipine (NF), verapamil (V), diltiazem (DL) and of the calmodulin antagonist trifluoperazine (TFP) on the activity of some drug-metabolizing enzyme systems, lipid peroxidation and acute acetaminophen toxicity were studied in male albino mice. No changes in the drug-metabolizing enzyme activities studied and in the cytochrome P-450 and b5 contents were observed 1 h after oral administration of V (20 mg/kg). DL (70 mg/kg) and TFP (3 mg/kg). NF (50 mg/kg) increased cytochrome P-450 content, NADPH-cytochrome c reductase and ethylmorphine-N-demethylase activities. DL and TFP significantly decreased lipid peroxidation. NF, V, DL and TFP administered 1 h before acetaminophen (700 mg/kg orally) increased the mean survival time of animals. A large increase of serum aspartate aminotransferase(AST), and liver weight and depletion of liver reduced glutathione (GSH) occurred in animals receiving toxic acetaminophen dose. NF, V and DL prevented and TFP decreased the acetaminophen-induced hepatic damage measured both by plasma AST and by liver weight. NF, V, DL and TFP changed neither the hepatic GSH level nor the GSH depletion provoked by the toxic dose of acetaminophen. This suggests that V, DL and TFP do not influence the amount of the acetaminophen toxic metabolite formed in the liver. The possible mechanism of the protective effect of NF, V, DL and TFP on the acetaminophen-induced toxicity is discussed.
Assuntos
Acetaminofen/toxicidade , Bloqueadores dos Canais de Cálcio/farmacologia , Calmodulina/antagonistas & inibidores , Trifluoperazina/farmacologia , Acetaminofen/antagonistas & inibidores , Animais , Aspartato Aminotransferases/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Diltiazem/farmacologia , Glutationa/efeitos dos fármacos , Glutationa/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Camundongos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Nifedipino/farmacologia , Taxa de Sobrevida , Verapamil/farmacologiaRESUMO
The effect of multiple nifedipine administration on hexobarbital sleeping time, liver monooxygenase and synthetase activities, lipid peroxidation and microsomal membrane fluidity were studied in male albino mice. The drug was administered orally at a dose of 25 mg/kg daily for 14 and 21 days. Nifedipine caused enzyme induction, demonstrated by shortened hexobarbital sleeping time, enhanced ethylmorphine N-demethylase, aniline 4-hydroxylase, ethoxycoumarine O-deethylase, UDP-glucuronyl transferase, glutathione S-transferase and NADPH-cytochrome c reductase activities and increased content of cytochrome P450 and cytochrome b5. This effect persisted until the 7th day after the last dose of nifedipine. There were no changes in lipid peroxidation and fluidity of the microsomal membranes after 14-day nifedipine administration. The increased cytochrome P450 content and drug metabolizing enzyme activities could be not associated with changes in these liver microsomal membrane properties.