Late heat damage in normal swine rectum: a comparison of thermosensitivity of rectum and oesophagus.

The normal swine rectum was heated using an intracavitary microwave radiator for 30 min at 43, 44, 45, 46, 47, and 48 degrees C. The animals were sacrificed 30 days later. The degree of heat injury was evaluated on a histological score system with a maximum possible damage score of 36 (100%). The scores for late damage were 8, 21, 23, 54, 58, and 74%, respectively. The 50% maximum damage was 45.8 +/- 0.5 degrees C/30 min. With the same score system, the heat damage to the oesophagus, which we have calculated previously, was evaluated and compared with that of the present data. The heat damage at the same temperature applied to the lumen was more severe in the rectum than that of the oesophagus. There was a roughly 2-3 degrees C difference in thermosensitivity between these two organs.