Tissue reaction to ischemia in the rabbit ear chamber: effects of prednisolone on inflammation and microvascular flow.

The rabbit ear containing a mature Lucite chamber was subjected to ischemia in 25 rabbits. The ischemic insult lasted in one group for 2 hours, in the second group for 5 hours, and in a third group for 5 hours with the addition of systemic prednisolone therapy. The gross edema of the ear, restoration of flow within the microvasculature in the rabbit ear chamber, and the occurrence and resolution of the cellular inflammatory response were documented by daily in vivo observations of the chamber. The 2-hour ischemic period resulted in a relatively insignificant injury, but the 5-hour ischemic period resulted in edema of the ear, changes in the flow within the microvasculature, and a cellular inflammatory response that increased in intensity for the first 24 hours following ischemia. Ultimate resolution of these changes was noted in all the animals. Systemic administration of prednisolone dramatically reduced the occurrence of edema and reduced the intensity of the inflammatory response, which resolved in a shorter period of time than in untreated animals. These studies demonstrate that ischemia evokes a classic inflammatory response that is inhibited by the administration of systemic steroids.