Detection by 32P-postlabelling of 8-oxo-7,8-dihydro-2′-deoxyguanosine in DNA as biomarker of microcystin-LR- and nodularin-induced DNA damage in vitro in primary cultured rat hepatocytes and in vivo in rat liver

It has been proposed that, during metabolic acidosis, the liver downregulates mitochondrial ammonia detoxification via ureagenesis, a bicarbonate-consuming process. Since we previously demonstrated that hepatocyte mitochondrial aquaporin-8 channels (mtAQP8) facilitate the uptake of ammonia and its metabolism into urea, we studied whether mtAQP8 is involved in the liver adaptive response to acidosis. Primary cultured rat hepatocytes were adapted to acidosis by exposing them to culture medium at pH 7.0 for 40 h. Control cells were exposed to pH 7.4. Hepatocytes exposed to acid medium showed a decrease in mtAQP8 protein expression (–30%, p < 0.05). Ureagenesis from ammonia was assessed by incubating the cells with 15N-labeled ammonia and measuring 15N-labeled urea synthesis by nuclear magnetic resonance. Reduced ureagenesis was found in acidified hepatocytes (–31%, p < 0.05). In vivo studies in rats subjected to 7 days acidosis also showed decreased protein expression of hepatic mtAQP8 (–50%, p < 0.05) and reduced liver urea content (–35%; p < 0.05). In conclusion, our in vitro and in vivo data suggest that hepatic mtAQP8 expression is downregulated in acidosis, a mechanism that may contribute to decreased ureagenesis from ammonia in response to acidosis.

Download Full-text

Identification of genes early responsive to gamma-irradiation in isolated rat hepatocytes in vitro and rat liver in vivo by cDNA array gene expression analysis

Zeitschrift für Gastroenterologie ◽

10.1055/s-2005-920060 ◽

2005 ◽

Vol 43 (05) ◽

Author(s):

DS Batusic ◽

H Christiansen ◽

B Saile ◽

RM Hermann ◽

J Dudas ◽

...

Keyword(s):

Gene Expression ◽

Gamma Irradiation ◽

Rat Liver ◽

Gene Expression Analysis ◽

Cdna Array ◽

Rat Hepatocytes ◽

Isolated Rat Hepatocytes ◽

Isolated Rat

Download Full-text

The Use of Primary Cultured Rat Hepatocytes for the Assessment of Xenobiotic Effects on Biotransformation

Alternatives to Laboratory Animals ◽

10.1177/026119299101900211 ◽

1991 ◽

Vol 19 (2) ◽

pp. 209-213

Author(s):

Gabi Schepers ◽

Christiane Aschmann ◽

Sabine Mörchel

Keyword(s):

Cell Viability ◽

Rat Hepatocytes ◽

Standard Test ◽

In Vitro Test ◽

Chlorinated Phenols ◽

Test Protocol ◽

Primary Cultured Rat Hepatocytes ◽

Cultured Rat Hepatocytes ◽

Different Response

An in vitro test protocol is reported, which, using primary cultured rat hepatocytes, allows for the screening of xenobiotic effects on biotransformation as well as on basal cellular functions. O-Deethylation of 7-ethoxycoumarin (7-EC) and subsequent conjugation of the metabolite 7-hydroxycoumarin (7-HC) with sulphate or glucuronic acid are determined, as representative parameters for the hepatic biotransformation. Cell viability is examined by measuring cellular ATP content and leakage of lactate dehydrogenase. With respect to immediate and delayed effects on biotransformation reactions, the standard test protocol includes exposure to xenobiotics for 1, 24 and 48 hours. Different response patterns could be demonstrated for the solvents dimethylformamide (DMF) and dimethylsulphoxide (DMSO), and the chlorinated phenols, pentachlorophenol (PCP) and hexachlorophene (HCP), which are known to uncouple mitochondrial respiration. Short-term incubation with the solvents resulted in decreased 7-EC- O-deethylation without signs of cytotoxicity. PCP and HCP inhibited 7-EC- O-deethylation and 7-HC-conjugation, affecting sulphate and glucuronide formation differently. 24-hour exposures to PCP and HCP resulted in decreased 7-ethoxycoumarin- O-deethylase activity, which correlated with diminished cell viability, while DMSO and DMF enhanced 7-EC- O-deethylation at sub-cytotoxic concentrations. After exposure for 48 hours to the solvents, enzyme induction was even more pronounced.

Download Full-text