Relation between renal and hepatic excretion of drugs: VII. Hepatic and renal excretion of phenol red in thioacetamide-induced acute and chronic liver damage

Changes in urinary taurine and hypotaurine excretion after two-thirds hepatectomy in the rat

This study followed the time course of urinary taurine and hypotaurine excretion after two-thirds hepatectomy in rats. The excretion of both taurine and hypotaurine was elevated during 18 h following the hepatectomy, with maximal excretion during the first 6 h. Twelve and 24 h after partial hepatectomy, the hepatic hypotaurine concentration was increased but liver taurine did not differ significantly from controls. No changes were observed in hypotaurine and taurine concentrations of heart, kidney, lung, muscle tissue and spleen. We postulate that partial hepatectomy induces a rapid increase of hepatic (hypo)taurine synthesis from precursor amino acids. The increased (hypo)taurine concentrations spill over into urine.

Hemodynamic characterization in experimental liver cirrhosis induced by thioacetamide administration

Systemic and splanchnic hemodynamics in experimental liver cirrhosis in rats induced by thioacetamide were evaluated by the radioactive microsphere method. Cardiac output and regional blood flow were measured in conscious and anesthetized control and cirrhotic rats. The conscious thioacetamide-treated rats had hyperdynamic circulation with an increased cardiac index (300 +/- 10 vs 258 +/- 3 ml/min/kg body weight, P < 0.001) and increased portal venous inflow compared with the controls (64.60 +/- 2.4 vs 48.39 +/- 0.88 ml/min/kg body weight, P < 0.001). Under pentobarbital anesthesia, the hyperdynamic circulation of the cirrhotic rats was maintained, with an increased cardiac index (276 +/- 7 vs 229 +/- 5 ml/min/kg body weight, P < 0.001) and increased protal venous inflow compared with the controls (72.47 +/- 3.0 vs 54.08 +/- 1.2 ml/min/kg body weight, P < 0.001). Portal pressure, portal venous resistance, and portal systemic shunting increased significantly while splanchnic arterial resistance decreased significantly in cirrhotic rats. Thioacetamide-induced cirrhosis is a useful model for the hemodynamic study of portal hypertension and remains useful in hemodynamic studies in the basal state under pentobarbital anesthesia.

Experimental treatment of thioacetamide-induced liver cirrhosis by metenolone acetate. A morphological and biochemical study

The influence of metenolone acetate (1 mg/kg b.m. orally) on intact and chronically thioacetamide-injured rat liver (experimental liver cirrhosis) was investigated over 14 d. Histological examination revealed nodular transformation of liver structure according to cirrhosis like lesions with hepatocellular and cholangiocellular proliferations. These structural alterations were more serious in the group treated with metenolone compared with the group without metenolone. Metanolone administration to animals with thioacetamide-induced experimental liver cirrhosis led to an increase in liver injury. This treatment seems to promote hepatic preneoplastic lesions induced by thioacetamide reflected by histology and induction of gamma-glutamyltranspeptidase and 7-ethoxycoumarin O-deethylase in injured livers. Metenolone did not interfere directly with the processes of connective tissue synthesis and degradation after thioacetamide pretreatment. Only little changes of the investigated biochemical parameters were seen after metenolone administration to animals with intact liver function: increases in serum cholinesterase and tissue N-acetyl-beta-D-glucosaminidase activity; decreases in N-acetyl-beta-D-glucosaminidase in serum, liver hydroxyproline content and hepatic gamma-glutamyltranspeptidase activity. The observed changes reflect hepatic adaption processes under the influence of metenolone. The results of this study indicate that the risk of anabolic steroids in adjuvant therapy of liver cirrhosis cannot be calculated at present.

Glutathione synthesis and export in experimental liver cirrhosis induced by thioacetamide: relations to ultrastructural changes

Micro-and macronodular experimental liver cirrhosis was induced in female rats by administration of 0.03% thioacetamide (TAA) in drinking water for 3 or 6 months, respectively. The glutathione (GSH) status (content, synthesis, export) and ultrastructural changes of liver were investigated 14 d after withdrawal of TAA. The hepatic level of GSH was increased after 6 months TAA treatment. The levels of oxidized glutathione (GSSG) were not changed after 3 months or 6 months TAA administration. The GSH synthesis was not disturbed in the cirrhotic livers; only the ratio between the 2 synthesizing enzymes was changed in macronodular liver cirrhosis. The plasma GSH content was reduced in both cases, independent of the stage of liver cirrhosis. The electron microscopic studies on cirrhotic rat livers revealed a series of characteristic structural changes, such as disorganization and total lack of the microvilli border, appearance of basement membrane-like deposits within the narrowed space of Disse, disappearance of the highly porous endothelial cell lining and partly an intensively detoriated blood supply within the pseudolobules. It is suggested that all these changes may contribute to a disturbance of the GSH export from the hepatocytes into the blood. It is very likely, however, that the alterations of the sinusoidal cell surface play the most important role. 1. The GSH/GSSG redox potential is shifted in favour of the reduced form in this cirrhosis model. This shift seems to be connected with later stages of cirrhogenesis. 2. A GSH export disturbance is responsible for the decreased plasma GSH level in liver cirrhosis.