RESUMO
The process of regenerating liver is the result of a balance between stimulating factors and inhibitors of hepatocyte proliferation. Melatonin and its metabolites have been found to protect tissues against oxidative damage generated by a variety of toxic agents and metabolic processes. Furthermore, studies in liver of rats showed a decrease in the liver mitochondrial hydroxylation of drugs returning to the normal state after the administration of antioxidants. This study was designed to determine, in experimental animals, whether the administration of an antioxidant agent such as melatonin could prevent cells events leading to tissue injury and hepatic dysfunction after partial hepatectomy (PH). Biliary flow (BF), oxidative stress in hepatic tissue and Naâº/K⺠ATPase activities in whole plasma membrane were determined. PH decreased the Naâº/K⺠ATPase activity. PH significantly reduced the BF (36%) and promoted oxidative stress with an increase of lipoperoxidation and decrease of glutathione peroxidase and catalase activities. Treatment with melatonin prevented the decrease of BF in rats with hepatectomy and normalized the Naâº/K⺠ATPase activity. Moreover, melatonin markedly attenuated oxidative stress produced by PH. This may be the results of the higher efficacy of melatonin in scavenging various free radicals and also because of its ability in stimulating the antioxidant enzymes. We suggest that oxidative stress before and during liver regeneration has a crucial role in cholestasis, apoptotic/necrotic hepatocellular damage and the impairment in liver transport function induced by PH and that melatonin could modulate the degree of oxidative stress and through it prevent the alterations in liver function carrier.
Assuntos
Regeneração Hepática/efeitos dos fármacos , Fígado/efeitos dos fármacos , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Algoritmos , Animais , Antioxidantes/farmacologia , Área Sob a Curva , Sistema Biliar/efeitos dos fármacos , Sistema Biliar/metabolismo , Sistema Biliar/fisiologia , Catalase/metabolismo , Corantes/farmacocinética , Glutationa Peroxidase/metabolismo , Hepatectomia/métodos , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/fisiopatologia , Fígado/cirurgia , Masculino , Taxa de Depuração Metabólica , Ratos , Ratos Wistar , ATPase Trocadora de Sódio-Potássio/metabolismo , Sulfobromoftaleína/farmacocinética , Fatores de TempoRESUMO
The insults sustained by transplanted livers (hepatectomy, hypothermic preservation, and normothermic reperfusion) could compromise hepatic function. Hydrogen sulfide (H2S) is a physiologic gaseous signaling molecule, like nitric oxide (NO) and carbon monoxide (CO). We examined the effect of diallyl disulfide as a H2S donor during hypothermic preservation and reperfusion on intrahepatic resistance (IVR), lactate dehydrogenase (LDH) release, bile production, oxygen consumption, bromosulfophthalein (BSP) depuration and histology in an isolated perfused rat liver model (IPRL), after 48 h of hypothermic storage (4 °C) in University of Wisconsin solution (UW, Viaspan). Livers were retrieved from male Wistar rats. Three experimental groups were analyzed: Control group (CON): IPRL was performed after surgery; UW: IPRL was performed in livers preserved (48 h-4 °C) in UW; and UWS: IPRL was performed in livers preserved (48 h-4 °C) in UW in the presence of 3.4 mM diallyl disulfide. Hypothermic preservation injuries were manifested at reperfusion by a slight increment in IHR and LDH release compared with the control group. Also, bile production for the control group (1.32 µL/min/g of liver) seemed to be diminished after preservation by 73% in UW and 69% in UW H2S group at the end of normothermic reperfusion. Liver samples analyzed by hematoxylin/eosin clearly showed the deleterious effect of cold storage process, partially reversed (dilated sinusoids and vacuolization attenuation) by the addition of a H2S delivery compound to the preservation solution. Hepatic clearance (HC) of BSP was affected by cold storage of livers, but there were no noticeable differences between livers preserved with or without diallyl disulfide. Meanwhile, livers preserved in the presence of H2S donor showed an enhanced capacity for BSP uptake (k(A) CON = 0.29 min⻹; k(A) UW = 0.29 min⻹ ; k(A) UWS = 0.36 min ⻹). In summary, our animal model suggests that hepatic hypothermic preservation for transplantation affects liver function and hepatic depuration of BSP, and implies that the inclusion of an H2S donor during hypothermic preservation could improve standard methods of preparing livers for transplant.
Assuntos
Compostos Alílicos/farmacologia , Isquemia Fria , Dissulfetos/farmacologia , Sulfeto de Hidrogênio/metabolismo , Transplante de Fígado , Fígado/efeitos dos fármacos , Soluções para Preservação de Órgãos/farmacologia , Preservação de Órgãos/métodos , Traumatismo por Reperfusão/prevenção & controle , Adenosina/farmacologia , Alopurinol/farmacologia , Compostos Alílicos/metabolismo , Animais , Bile/metabolismo , Isquemia Fria/efeitos adversos , Dissulfetos/metabolismo , Gases , Glutationa/farmacologia , Glicogênio/metabolismo , Insulina/farmacologia , L-Lactato Desidrogenase/metabolismo , Fígado/irrigação sanguínea , Fígado/metabolismo , Fígado/patologia , Fígado/cirurgia , Circulação Hepática , Testes de Função Hepática , Masculino , Preservação de Órgãos/efeitos adversos , Consumo de Oxigênio/efeitos dos fármacos , Rafinose/farmacologia , Ratos , Ratos Wistar , Traumatismo por Reperfusão/etiologia , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Sulfobromoftaleína/metabolismo , Fatores de Tempo , Resistência VascularRESUMO
The kidneys and liver are the major routes for organic anion elimination. We have recently shown that acute obstructive jaundice is associated with increased systemic and renal elimination of two organic anions, p-aminohippurate and furosemide, principally excreted through urine. This study examined probable adaptive mechanisms involved in renal elimination of bromosulfophthalein (BSP), a prototypical organic anion principally excreted in bile, in rats with acute obstructive jaundice. Male Wistar rats underwent bile duct ligation (BDL rats). Pair-fed sham-operated rats served as controls. BSP renal clearance was performed by conventional techniques. Renal organic anion-transporting polypeptide 1 (Oatp1) expression was evaluated by immunoblotting and IHC. Excreted, filtered, and secreted loads of BSP were all higher in BDL rats compared with Sham rats. The higher BSP filtered load resulted from the increase in plasma BSP concentration in BDL rats, because glomerular filtration rate showed no difference with the Sham group. The increase in the secreted load might be explained by the higher expression of Oatp1 observed in apical membranes from kidneys of BDL animals. This likely adaptation to hepatic injury, specifically in biliary components elimination, might explain, at least in part, the huge increase in BSP renal excretion observed in this experimental model.
Assuntos
Colestase Extra-Hepática/metabolismo , Icterícia Obstrutiva/metabolismo , Rim/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/fisiologia , Sulfobromoftaleína/farmacocinética , Doença Aguda , Animais , Ânions , Immunoblotting , Imuno-Histoquímica , Masculino , Microvilosidades/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/biossíntese , Ratos , Ratos WistarRESUMO
Animal studies and premarketing clinical trials have revealed hepatotoxicity of statins, primarily minor elevations in serum alanine aminotransferase levels. The combined chronic use of medicines and eventual ethanol abuse are common and may present a synergistic action regarding liver injury. Our objective was to study the effect of the chronic use of atorvastatin associated with acute ethanol administration on the liver in a rat model. One group of rats was treated daily for 5 days a week for 2 months with 0.8 mg/kg atorvastatin by gavage. At the end of the treatment the livers were perfused with 72 mM ethanol for 60 min. Control groups (at least 4 animals in each group) consisted of a group of 2-month-old male Wistar EPM-1 rats exposed to 10% ethanol (v/v) ad libitum replacing water for 2 months, followed by perfusion of the liver with 61 nM atorvastatin for 60 min, and a group of animals without chronic ethanol treatment whose livers were perfused with atorvastatin and/or ethanol. The combination of atorvastatin with ethanol did not increase the release of injury marker enzymes (alanine aminotransferase, aspartate aminotransferase, and lactic dehydrogenase) from the liver and no change in liver function markers (bromosulfophthalein clearance, and oxygen consumption) was observed. Our results suggest that the combination of atorvastatin with ethanol is not more hepatotoxic than the separate use of each substance.
Assuntos
Etanol/toxicidade , Ácidos Heptanoicos/toxicidade , Fígado/efeitos dos fármacos , Pirróis/toxicidade , Alanina Transaminase/sangue , Animais , Aspartato Aminotransferases/sangue , Atorvastatina , Biomarcadores/sangue , Sinergismo Farmacológico , Etanol/administração & dosagem , Ácidos Heptanoicos/administração & dosagem , L-Lactato Desidrogenase/sangue , Fígado/enzimologia , Fígado/patologia , Testes de Função Hepática , Masculino , Consumo de Oxigênio , Perfusão , Pirróis/administração & dosagem , Ratos , Ratos Wistar , Sulfobromoftaleína/farmacocinéticaRESUMO
Animal studies and premarketing clinical trials have revealed hepatotoxicity of statins, primarily minor elevations in serum alanine aminotransferase levels. The combined chronic use of medicines and eventual ethanol abuse are common and may present a synergistic action regarding liver injury. Our objective was to study the effect of the chronic use of atorvastatin associated with acute ethanol administration on the liver in a rat model. One group of rats was treated daily for 5 days a week for 2 months with 0.8 mg/kg atorvastatin by gavage. At the end of the treatment the livers were perfused with 72 mM ethanol for 60 min. Control groups (at least 4 animals in each group) consisted of a group of 2-month-old male Wistar EPM-1 rats exposed to 10 percent ethanol (v/v) ad libitum replacing water for 2 months, followed by perfusion of the liver with 61 nM atorvastatin for 60 min, and a group of animals without chronic ethanol treatment whose livers were perfused with atorvastatin and/or ethanol. The combination of atorvastatin with ethanol did not increase the release of injury marker enzymes (alanine aminotransferase, aspartate aminotransferase, and lactic dehydrogenase) from the liver and no change in liver function markers (bromosulfophthalein clearance, and oxygen consumption) was observed. Our results suggest that the combination of atorvastatin with ethanol is not more hepatotoxic than the separate use of each substance.
Assuntos
Animais , Masculino , Ratos , Etanol/toxicidade , Ácidos Heptanoicos/toxicidade , Fígado/efeitos dos fármacos , Pirróis/toxicidade , Alanina Transaminase/sangue , Aspartato Aminotransferases/sangue , Biomarcadores/sangue , Sinergismo Farmacológico , Etanol/administração & dosagem , Ácidos Heptanoicos/administração & dosagem , L-Lactato Desidrogenase/sangue , Testes de Função Hepática , Fígado/enzimologia , Fígado/patologia , Consumo de Oxigênio , Perfusão , Pirróis/administração & dosagem , Ratos Wistar , Sulfobromoftaleína/farmacocinéticaRESUMO
The effects of a chronic aluminum (Al) exposure on biliary secretory function, with special emphasis on hepatic handling of non-bile salt organic anions, was investigated. Male Wistar rats received, intraperitoneally, either 27 mg/kg body weight of Al, as Al hydroxide [Al (+) rats], or the vehicle saline [Al (-) rats] three times a week for 3 months. Serum and hepatic Al levels were increased by the treatment (approximately 9- and 4-fold, respectively). This was associated with enhanced malondialdehyde formation (+110%) and a reduction in GSH content (-17%) and in the activity of the antioxidant enzymes catalase (-84%) and GSH peroxidase (-46%). Bile flow (-23%) and the biliary output of bile salts (-39%), cholesterol (-43%), and proteins (-38%) also decreased. Compartmental analysis of the plasma decay of the model organic anion bromosulphophthalein revealed that sinusoidal uptake and canalicular excretion of the dye were significantly decreased in Al (+) rats (-53 and -43%, respectively). Expression of multidrug resistance-associated protein 2 (Mrp2), the main, multispecific transporter involved in the canalicular excretion of organic anions, was also decreased (-40%), which was associated with a significant decrease in the cumulative biliary excretion of the Mrp2 substrate, dinitrophenyl-S-glutathione (-50%). These results show that chronic Al exposure leads to oxidative stress, cholestasis, and impairment of the hepatic handling of organic anions by decreasing both sinusoidal uptake and canalicular excretion. The alteration of the latter process seems to be causally related to impairment of Mrp2 expression. We have addressed some possible mechanisms involved in these deleterious effects.
Assuntos
Alumínio/intoxicação , Canalículos Biliares/efeitos dos fármacos , Canalículos Biliares/metabolismo , Bile/metabolismo , Glutationa/análogos & derivados , Hidróxido de Alumínio/administração & dosagem , Hidróxido de Alumínio/sangue , Hidróxido de Alumínio/intoxicação , Animais , Bile/efeitos dos fármacos , Ácidos e Sais Biliares/antagonistas & inibidores , Ácidos e Sais Biliares/metabolismo , Catalase/antagonistas & inibidores , Catalase/metabolismo , Colestase/induzido quimicamente , Colesterol/metabolismo , Doença Crônica , Esquema de Medicação , Avaliação Pré-Clínica de Medicamentos/métodos , Expressão Gênica , Glutationa/antagonistas & inibidores , Glutationa/química , Glutationa/efeitos dos fármacos , Glutationa/metabolismo , Glutationa Peroxidase/antagonistas & inibidores , Glutationa Peroxidase/metabolismo , Glutationa Transferase/química , Glutationa Transferase/metabolismo , Injeções Intraperitoneais , Fígado/química , Fígado/efeitos dos fármacos , Masculino , Proteínas Mitocondriais/antagonistas & inibidores , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Proteínas/antagonistas & inibidores , Proteínas/metabolismo , Ratos , Ratos Wistar , Proteínas Ribossômicas/antagonistas & inibidores , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Sulfobromoftaleína/metabolismo , Sulfobromoftaleína/farmacocinética , Substâncias Reativas com Ácido Tiobarbitúrico/química , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
BSP/Bilirubin binding protein (BBBP) is a protein located on the sinusoidal membrane of the liver that transport several organic anions. The aim of this investigation was to determine whether BBBP is present in the kidney and its role in p-aminohippurate transport (PAH). Anti-BBBP antibodies inhibited PAH uptake in brush border membrane vesicles (BBMV) and Na(+)-independent PAH uptake in basolateral membrane vesicles (BLMV). Western blot studies revealed positivity to antiBBBP antibodies in both BBMV and BLMV. So BBBP is also expressed in the kidneys and accounts, at least in part, for the renal tubular transport of PAH.
Assuntos
Proteínas de Transporte/metabolismo , Rim/metabolismo , Sulfobromoftaleína/metabolismo , Ácido p-Aminoipúrico/metabolismo , Animais , Anticorpos/farmacologia , Transporte Biológico/efeitos dos fármacos , Feminino , Cinética , Masculino , Microvilosidades/metabolismo , Ratos , Ratos WistarRESUMO
The action of extracellular ATP on organic anion transport in the bivascularly perfused rat liver was investigated, using bromosulfophthalein as a model substance. Transport was measured by means of the multiple-indicator dilution technique. The action of portal 100 microM ATP presented the following characteristics: (a) inhibition of bromosulfophthalein single pass extraction; the inhibition degree decreased with increasing bromosulfophthalein doses; (b) diminution of the influx rate coefficients; (c) 86.7% decrease of the maximal activity of the saturable component for bromosulfophthalein transport, but 100% increase of the non-saturable component; (d) diminution of the bromosulfophthalein flow-limited distribution space; (e) no significant alteration of the rate coefficients for metabolic sequestration. The action of ATP on organic anion transport in the intact liver occurred at much lower concentrations (10x) than those previously reported for isolated hepatocytes. This reinforces the suggestion that inhibition of organic anion transport could be a physiologically relevant effect of extracellular ATP.
Assuntos
Trifosfato de Adenosina/farmacologia , Espaço Extracelular/efeitos dos fármacos , Fígado/efeitos dos fármacos , Sulfobromoftaleína/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Relação Dose-Resposta a Droga , Espaço Extracelular/metabolismo , Fígado/metabolismo , Masculino , Transportadores de Ânions Orgânicos Dependentes de ATP/antagonistas & inibidores , Transportadores de Ânions Orgânicos Dependentes de ATP/metabolismo , Perfusão/métodos , Ratos , Ratos WistarRESUMO
Adaptive hepatic changes were investigated in rats with mild stenosis of the common bile duct and in sham-operated controls. The studies were performed 24 h and 7-12 days postoperatively. A continuous intravenous infusion of taurocholic acid at stepwise-increasing rates was performed to explore the responses to bile acid effects. During the infusion, bile flow and the outputs of bile acids, phospholipids, cholesterol, alkaline phosphatase and gamma glutamyl transpeptidase were studied. At the end of the infusion, hepatic morphometric measurements were performed. In other experimental sets, biliary excretions of horseradish peroxidase, a marker of microtubule-dependent vesicular transport in the hepatocyte, and sulphobromophthalein, a well-known organic anion model, were studied. In other rats, bile acid pool size and composition were determined by depletion of bile. The results in rats with mild stenosis maintained for 24 h showed a greater susceptibility to the toxicity of taurocholic acid, as revealed by the abrupt decrement in bile flow at high rates of infusion, and increased outputs of phospholipids and canalicular enzymes. Conversely, rats with mild stenosis maintained for 7-12 days showed decreased bile acid maximum secretory rate and biliary outputs of phospholipids and canalicular enzymes, as well as hepatocyte hypertrophy. These findings may explain the limited hepatic and systemic repercussion of experimental mild stenosis of the common bile duct and help us to understand the early stages of constriction of the common bile duct in man.
Assuntos
Adaptação Fisiológica/fisiologia , Colestase Extra-Hepática/patologia , Doenças do Ducto Colédoco/patologia , Fígado/enzimologia , Fosfatase Alcalina/metabolismo , Animais , Ácidos e Sais Biliares/análise , Ácidos e Sais Biliares/metabolismo , Colestase Extra-Hepática/metabolismo , Doenças do Ducto Colédoco/metabolismo , Constrição Patológica , Peroxidase do Rábano Silvestre/farmacocinética , Concentração de Íons de Hidrogênio , Injeções Intravenosas , Fígado/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Sulfobromoftaleína/farmacocinética , Ácido Taurocólico/farmacologia , gama-Glutamiltransferase/metabolismoRESUMO
The hepatic uptake of the bilirubin-bilirubin-sulfobromophthalein (BSP) group of organic anions is a carrier-mediated process and is accounted for by at least four distinct plasma membrane proteins (bilitranslocase, BSP/bilirubin-binding protein, organic anion-binding protein and the organic anion transport protein). In order to investigate the regulation of basolateral organic anion uptake, BSP transport was measured in rat basolateral liver plasma membrane vesicles in the presence of ATP. ATP significantly stimulated the electroneutral uptake of BSP with an increment in Vmax compared with control (1.57 +/- 0.14 vs 0.73 +/- 0.06 nmol BSP/mg protein per 15 s, respectively; P < 0.001) while the apparent K(m) was not changed significantly (12 +/- 1 vs 12 +/- 2 mumol/L). The stimulatory effect was dose-dependent for ATP (K(m) 1.01 +/- 0.37 mmol/L). ATP had no detectable effect on the electrogenic component of BSP transport. Other nucleotides (ADP, AMP, GTP) and non-hydrolysable ATP did not enhance BSP uptake, suggesting that ATP hydrolysis was necessary for the effect. This was supported by the lack of effect on BSP uptake when ATP was added in the presence of vanadate. The addition of phorbol-12-myristate 13-acetate, an activator of protein kinase C (PKC), increased BSP uptake in a dose-dependent manner in the presence, but not in the absence, of ATP. Incubation of vesicles with staurosporine, an inhibitor of PKC activity, resulted in a dose-dependent inhibition of ATP-sensitive BSP transport. These data indicate that electroneutral BSP hepatic uptake is modulated by ATP. The effect is related to ATP hydrolysis and involves the activity of PKC.