Inflammation and the vascular changes due to thermal injury in rat hind paws.

The vascular changes due to thermal injury have been determined in rat hind paws. In anaesthetized rats one hind paw has been injured by immersion in water for 30 seconds; temperature range 49-65 degrees C. Changes in blood flow, blood content and albumin content have been determined and compared with values from uninjured rats. The swelling caused by thermal injury was temperature-dependent, the higher temperatures caused the larger swellings. There were also temperature-dependent increases in blood flow to the injured paw and albumin content of the injured paw. Changes in blood content only occurred at the highest temperatures. Swelling, increased blood flow and albumin content could be detected within 1 minute of injury. The swelling and albumin content of the tissue then continued to increase gradually. The increase in blood flow was greatest 1 minute after injury and then stabilized at a flow some 4-5 times higher than normal paw flow. The method described can be used to measure vascular changes due to other inflammatory stimuli and could be applied to measure changes in other discreet areas.