ABSTRACT
Increased production of oxygen free radicals and infiltration of neutrophils into tissue subjected to ischemia-reperfusion have emphasized that neutrophils play a direct role in the development of injury. The present study was designed to elucidate the effect of FK506, a new immunosuppressive drug, on 11 hours of complete ischemia and reperfusion of the inguinal island skin flaps in rats. Group 1 (n = 10) control animals underwent ischemia and reperfusion and no treatment. Group 2 (n = 10) animals received FK 506 0.3 mg/kg/day, and group 3 (n = 9) animals received 0.5 mg/kg/day intramuscularly for 3 days before the ischemia. The effect of the drug was evaluated by measuring flap survival and tissue malondialdehyde content and myeloperoxidase activity and also by histopathologic examination of the skin specimens taken at the 1st and 24th hour after reperfusion. The survival of flaps controlled for 7 days was found to be significantly improved in group 2 (65.0 +/- 10.93 percent) and group 3 (93 +/- 6.25 percent) when compared with the control group (14 +/- 10.12 percent) (p < 0.04 and p < 0.0001). The tissue contents of malondialdehyde and activities of myeloperoxidase were significantly lower in groups 2 and 3 than in the control group. Three days of pretreatment with FK506 significantly reduced neutrophil infiltration in groups treated with either of the doses. These results showed that neutrophils play an important role in island flap survival associated with ischemia-reperfusion injury. Increased neutrophil infiltration was found related with increased levels of malondialdehyde and myeloperoxidase. Flap necrosis and the increase in malondialdehyde, myeloperoxidase, and neutrophil infiltration were improved by FK506 pretreatment, a neutrophil modulating agent.
Subject(s)
Neutrophils/physiology , Reperfusion Injury/pathology , Skin Transplantation/pathology , Surgical Flaps/pathology , Animals , Free Radicals/metabolism , Graft Survival/drug effects , Groin , Immunosuppressive Agents/administration & dosage , Immunosuppressive Agents/therapeutic use , Injections, Intramuscular , Ischemia/metabolism , Ischemia/pathology , Ischemia/physiopathology , Leukocyte Count/drug effects , Male , Malondialdehyde/analysis , Neutrophil Activation/drug effects , Neutrophils/drug effects , Peroxidase/analysis , Rats , Rats, Wistar , Reactive Oxygen Species/metabolism , Reperfusion Injury/metabolism , Reperfusion Injury/prevention & control , Skin/chemistry , Skin/enzymology , Skin/pathology , Skin Transplantation/physiology , Surgical Flaps/blood supply , Surgical Flaps/physiology , Tacrolimus/administration & dosage , Tacrolimus/therapeutic useABSTRACT
The purpose of this study was to investigate the role of neutrophils in ischemic tissue injury and the possible inhibition by pretreatment with FK506, a neutrophilic modulating agent. A dorsal caudally based skin flap (3 x 9 cm) was used as an ischemic injury model in experimental groups. Prior to flap elevation, FK506 at doses of 0.3 mg per kilogram (group 2), 0.5 mg per kilogram (group 3), and 1.0 mg per kilogram (group 4) was given for 3 days intramuscularly. The relationship among neutrophil accumulation (histopathologically), myeloperoxidase (MPO) activity, malondialdehyde (MDA) content (biochemically) of the flap tissue, and flap survival were studied. Skin flaps showed reduced necrosis in the FK506-treated groups (p < 0.08, p < 0.0001, and p < 0.0001 respectively). The increase in accumulation of neutrophils, and MDA and MPO levels (which were induced by ischemia) observed 1 and 24 hours after flap elevation was diminished by FK506 pretreatment. The increased neutrophilic infiltration, and raised tissue MDA content and MPO activity revealed involvement of both free radical production and neutrophils in ischemia. This injury was decreased by FK506, probably by inhibition of neutrophilic chemotaxis, infiltration, and releasing factors.
