EFFECT OF ACUTE SKIN THERMAL-INJURY ON SUBCUTANEOUS GLUTATHIONE, ASCORBIC-ACID AND HYDROXYL RADICAL CONCENTRATIONS IN ANESTHETIZED RATS

The effect of acute thermal injury on subcutaneous oxidative stress, i n anesthetized rats, was evaluated. A microdialysis probe was implante d in the subcutaneous tissue for continuous sampling of interstitial f luids, and the microdialysates were injected onto either an on-line or an off-line high performance liquid chromatography system. Hydroxyl r adicals, glutathione, and ascorbic acid concentrations in the microdia lysates were analyzed. Acute thermal injury was induced by skin contac t of a hot (90 degrees C) iron bar for 30 or 15 s. Subcutaneous hydrox yl radical production, represented as the increased formation of 2,3 a nd 2,5 dihydroxybenzoic acid (DHBA), did not increase significantly af ter thermal contact. Interestingly, both ascorbic acid and glutathione , two major physiological antioxidants, were significantly elevated in the subcutaneous interstitial fluids immediately after thermal contac ts. The elevated subcutaneous glutathione levels rapidly decreased and returned to basal values 60 min after thermal contact. Ascorbic acid concentrations did not fully return to basal values even 3 h after the rmal contact. The increase in ascorbic acid and glutathione may be res ponsible for scavenging of hydroxyl radicals that may form following t hermal injury.