Effects of cooling after scald injury to a dorsal skin fold of mouse

Shaved trunk skin folds of hairy mice were scalded for 20 s by water immersion. In one set of experiments the effect of increasing burn temperature (51 degrees C-60 degrees C) was studied, in another the folds were first scalded at 51 degrees C-54 degrees C and then immediately cooled for 30 min in 8 degrees C water. Animals were killed 2 h and 4 days postburn. Before sacrifice, Evans blue was injected i.v. to some animals to visualize preserved vascular perfusion and areas of increased permeability. Macroscopic observations (and photographic documentation) were made of the outside and inside of the injured skin and biopsies for light microscopy were obtained centrally in the burns. The injured area was measured by planimetry on photographs and expressed in percent of the whole burned area. At 4 days, brownish, oval areas appeared on the skin being progressively larger with increasing burn temperature. The 51 degrees C burn only resulted in a very small, spotlike, tissue injury, while the greater than or equal to 52 degrees C produced a macroscopic necrosis amounting to 40%-94% of the burned area. Postburn cooling did not reduce the damaged area as recorded 4 days postburn. Histologically, the tissues seemed well preserved at 2 h after 51 degrees C scalds, whereas cell damage was obvious and increasingly pronounced after greater than or equal to 53 degrees C burns. After 52 degrees C burns a mixed picture emerged. A similar microscopic pattern was seen at 4 days; 51 degrees C specimens were undamaged, some 52 degrees C and all greater than or equal to 53 degrees C were necrotic.(ABSTRACT TRUNCATED AT 250 WORDS)