EFFECTS OF ENVIRONMENTAL-STRESS ON TISSUE SURVIVAL AND NEUTROPHIL RECRUITMENT IN SURGICAL SKIN FLAPS IN RELATION TO PLASMA-CORTICOSTERONE LEVELS IN THE RAT

Objective: Because glucocorticoid treatment can improve the survival o f surgical skin flaps, we examined the influence of environmental stre ss on skin flap survival in the rat. Material: Female Sprague-Dawley r ats. Treatment: Dexamethasone (1 mg/kg i.p.). Methods: A standardized dorsal skin flap was raised and sutured back into position, and six da ys later the percentage of flap survival was assessed. Corticosterone in rat plasma was measured using radioimmuno assay, and skin flap myel operoxidase accumulation (reflecting neutrophil recruitment) was deter mined spectrophotometrically. Results: Skin flap survival decreased gr adually during a 10 day acclimatization period after transportation of the animals from the supplier, and plasma corticosterone levels were increased during the first 5 days of acclimatization compared to day 7 and 10. Dexamethasone treatment of rats accustomed to their new envir onment for 10 days increased flap survival to a level close to that ob served in animals operated at day 1 after arrival. Flap surgery induce d pronounced neutrophil recruitment into flap tissue, and this cell ac cumulation was greatly reduced in both the dexamethasone treated rats and in rats with elevated corticosterone levels. Conclusions: Skin fla p survival in rats exposed to environmental stress may be significantl y increased as compared to animals accustomed to their new environment for one a consequence of anti-inflammatory stress-induced elevations in plasma corticosterone. These findings emphasize the importance of s trictly controlling environmental stress factors in studies of inflamm ation and tissue damage after surgical skin trauma.