[Non-contact experimental burns in rats].

Abstract

Both healthy female rats of the Wistar strain (VELAZ breed) and those irradiated with a single whole-body dose of 5 Gy gamma radiation (60Co) were exposed on the back to non-contact infrared radiation (IR lamp with an output of 250 W: skin surface temperature at a distance of 3 cm from the crown of the lamp = magnitude of 110 +/- 2 degrees C) for time periods of 40 s, 20 s, 10 s (healthy) and 20 s (irradiated animals). The surface range of thermic damage to the skin was determined using planimetry and measuring the length and the width of the burn with the respect to an immediate contraction. The mean values of an immediate retraction of the burnt skin and the interval of reliability of their estimate (p < 0.05) were significantly lower in 10 s exposure and in whole-body irradiation rats after 20 s (magnitude of 5.6 +/- 2.5 % ... 10 s; magnitude of 12.56 +/- 3.86 % ... in irradiated animals) than the retraction of non-irradiated rats (magnitude of 15.98 +/- 4.86 % ... in 20 s; magnitude of 31.88 +/- 7.34 % ... in 40 s). For a period of 90 min after burning, no substantial changes were found in rectal temperature (33.4 degrees C to 35.4 degrees C). Before a thermic trauma the drop in the temperature from the skin surface reached cca 2 degrees C subcutaneously, after burning in the centre of the burn about 17 degrees C and 9 degrees C in other exposures using the IR lamp. The mean time of burn healing in non-irradiated animals was the shortest in 10 s exposure (magnitude of 17 +/- 2 days), the damage in the centre reaching II b degree while after 40 s exposure the burn reached IV degree and also the longest healing time (magnitude of 60 +/- 4 days). After 20 s exposure, the mean healing times in irradiated rats were longer (magnitude of 39 +/- 3) days and so the skin damage (III to IV degree) as compared with non-irradiated animals where the mean healing time amounted to (34 +/- 4) days, the burns being of III degree.