Elevation of lung glutathione by oral supplementation of L-2-oxothiazolidine-4-carboxylate protects against oxygen toxicity in protein-energy malnourished rats.

Abstract

The objectives of this study were to investigate whether oral supplementation of L-2-oxothiazolidine-4-carboxylate (OTC) is effective for increasing tissue glutathione (GSH) concentrations in rats fed a diet very low (0.5%) in protein-a model of wasting malnutrition-and to determine the efficacy of OTC for protection against pulmonary oxygen toxicity. Weanling rats, fed a 0.5 or 15% protein diet for 2 wk, were given an oral supplement of OTC, and tissue GSH concentrations were measured over a 24 h period. OTC supplementation to rats fed 0.5% protein significantly increased GSH concentrations in liver and lung, but not in kidney and blood, when compared with the 0.5% protein unsupplemented group. The liver GSH concentration in the 0.5% protein OTC-supplemented group was higher than the 15% control group. Daily supplementation of OTC protected rats from pulmonary oxygen toxicity during 4 days of 85% oxygen exposure as determined by lung-to-body weight ratios and in vivo proton magnetic resonance imaging. Although hyperoxia exposure increased lung GSH concentrations in all groups, OTC supplementation was effective for increasing lung GSH concentration in rats fed the 0.5% protein diet. This study demonstrated that oral administration of OTC to wasting malnourished rats is an effective procedure to increase GSH concentration rapidly in target organs such as lung, and that daily supplementation of a low dose of OTC has a sustained effect to protect against pulmonary oxygen toxicity during 4 days of hyperoxia exposure.