OVAL ADMINISTRATION OF PURIFIED MICRONIZED FLAVONOID FRACTION SUPPRESSES LEUKOCYTE ADHESION IN ISCHEMIA-REPERFUSION INJURY - IN-VIVO OBSERVATIONS IN THE HAMSTER SKIN FOLD

The effect of a clinically used purified micronized flavonoid fraction (90% diosmin and 10% hesperidin) on leukocyte-endothelial cell intera ction during ischemia-reperfusion injury was studied in the microcircu lation of unanesthetized hamsters fitted with a skin fold window chamb er. The drug was given orally in suspension with arabic gum (30 mg/kg) 8 h prior to induction of 4-hour tourniquet ischemia in the chamber w indow. Leukocyte-endothelial cell interaction was observed using fluor escence intravital microscopy in postcapillary venules (15-70 mu m in diameter) at control and during reperfusion at 30 min and 2 and 24 h. Leukocytes were classified according to their flow pattern as (1) 'pas sers', including 'free flowing' leukocytes and those which were 'flowi ng with endothelial contact', and (2) 'immobilized' leukocytes. Untrea ted animals exhibited a significant increase of 'immobilized' leukocyt es and of those 'flowing with endothelial contact' during reperfusion. Flavonoid-treated animals displayed a statistically significant lower number of 'immobilized' leukocytes at all time points during reperfus ion. There was no change in the number of leukocytes 'flowing with end othelial contact' relative to the untreated animals. Since firm leukoc yte attachment to the endothelial wall and subsequent emigration of le ukocytes into the interstitium is a mechanism for tissue damage during inflammation, attenuation of this phenomenon during conditions of isc hemia-reperfusion can in part explain previous observations that this purified micronized flavonoid fraction decreases edema formation.