RESUMO
A system consisting of isolated rat hepatocytes immobilized in agarose threads continuously perifused with oxygenated Krebs-Henseleit (KH) solution has been found to maintain cell viability with excellent metabolic activity for more than 6 h. The hepatocytes were monitored by phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy at 4.7 Tesla, by measurement of oxygen consumption and by the leakage of lactate dehydrogenase (LD) and alanine aminotransferase (ALT). The data obtained were comparable to those found for an isolated perfused whole liver in vitro. The effects of allyl alcohol (AA), ethanol, and 4-acetaminophenol (AP) were examined. A solution of 225 microM AA perifused for 90 min caused the disappearance of the beta-phosphate resonance of adenosine triphosphate (ATP) in the 31P-NMR spectra, a 7-fold increase in LD leakage and a 70% reduction in oxygen consumption. Ethanol (1.0 M) perifused for 90 min reduced the beta-ATP signal intensity ratio by 20%, the phosphomonoester (PME) signal by 50% and inorganic phosphate (Pi) by 33% (P less than 0.05). AP (10 mM) caused only mild liver-cell damage. The results demonstrate that perifused immobilized hepatocytes can be used as a liver model to assess the effects of a wide range of chemicals and other xenobiotics by NMR spectroscopy.
Assuntos
Fígado/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Citosol/enzimologia , Metabolismo Energético/efeitos dos fármacos , Etanol/farmacologia , Técnicas In Vitro , L-Lactato Desidrogenase/análise , Fígado/enzimologia , Fígado/metabolismo , Espectroscopia de Ressonância Magnética , Masculino , Consumo de Oxigênio/efeitos dos fármacos , Perfusão , Ratos , Ratos Endogâmicos , SefaroseRESUMO
The effect of cyclosporine on liver regeneration has been investigated in 25 dogs that underwent an end-to-side portacaval shunt (Eck fistula) followed by 4 days continuous infusion of the drug into the left branch of the portal vein. Three different cyclosporine infusion rates were used: 0.06, 0.6, and 4.0 mg/kg/day. Control animals received the intravenous vehicle of cyclosporine at the same rate as the treated animals; a second control group received insulin, 0.42 units/kg/day. Hepatocyte 3H-thymidine-labeled mitoses (index of hyperplasia) and hepatocyte volume (index of hypertrophy) were studied in the left (infused) and right (control) lobes in each animal. Cyclosporine vehicle had no measurable effect on hepatocytes that suffered typical atrophy and moderate increase in mitotic index after the Eck fistula. Cyclosporine infusion stimulated cell renewal significantly and restored hepatocyte size in the infused lobes with a dose-response relation. Similar positive effects were observed in the right (nonperfused) lobes, although they were less than those in the left (infused) lobes. This was because of an unmistakable spillover of cyclosporine from the infused lobes, especially in the large-dose group. No sign of hepatotoxicity was detected at any cyclosporine infusion rate. Cyclosporine has a remarkable hepatotropic effect that may be helpful in the context of liver transplantation.