Correlation Between the in vitro and in vivo Nephrotoxicity of Parenteral Antibiotics in the Rabbit

Impact of cephaloridine on glutathione and related enzymes: comparison of in vivo and in vitro rat models

The aim of this study was to investigate the early effects of cephaloridine (CPH) on glutathione-dependent phase II detoxification in the rat proximal tubular cell and to find an in vitro alternative to the in vivo model. The in vivo study was conducted in three groups of rats which received CPH at doses of 250, 500 or 750 mg/kg per day for 3 days, while another group received 500 mg/kg as a single dose. For the in vitro study, rat renal proximal tubular cultured cells were exposed to CPH at concentrations of 0.3, 0.6, 1, 1.7 mM for 24, 48 and 72 h. Glutathione-dependent detoxification was evaluated in vivo and in vitro on the basis of total intracellular glutathione (GSH), glutathione S-transferase (GST) and glutathione peroxidase (GPX). Glutathione reductase (GRED) and GST mRNA levels were also determined. Results of in vivo and in vitro models were comparable in terms of the early increase of GSH, GST and GRED. This increase had a bell-shaped dose-response with a maximum at 500 mg/kg in vivo and 1 mM in vitro. Beyond these doses, GSH and its dependent enzyme levels decreased, associated with cytotoxicity in vitro and renal insufficiency in vivo. The increased GST activity was associated with an increased level of GST7 in vivo and a markedly increased level of GST1-2 in vitro. We concluded that the in vitro model can be used as an alternative to animal experimentation to study glutathione-dependent detoxication. Low cytotoxic doses of CPH induced an early increase of glutathione phase II-dependent detoxification enzymes.

Effects of quinidine on renal biochemistry and function in young and old rats

Nephrotoxic effects of quinidine in male Fischer-344 rats in ages of 3-4 months and 20-22 months were evaluated. Renal cortical slice oxygen consumption, accumulation of p-aminohippurate and tetraethyl ammonium were inhibited in vitro. No age-related differences were observed. Quinidine decreased respiratory control index and ADP/O ratio in both age groups. Quinidine administration at 75 mg/kg/day for four days reduced tetraethylammonium transport in both young and old. Blood urea nitrogen increased in the old, but not in the young rats. Serum creatinine levels were elevated in both age groups. Renal cortical slice oxygen consumption decreased in the young but not in the old rats after quinidine administration. No changes in RCI or ADP/O ratio were observed in the two age groups. The results indicate that Fischer-344 rats in the ages of 20-22 months are not increasingly susceptible to quinidine-induced nephrotoxicity.