Background. Recent studies have shown that the extent of platelet accumulation in the vasculature of transplanted organs correlates with the degree of preservation-reperfusion injury. In this study, we examined the effect of a stable prostacyclin analog, beraprost sodium, which possesses potent antiplatelet activity, on parameters of platelet accumulation and preservation-reperfusion injury of isografts in a rat model of lung transplantation. Methods. The heart-lung blocks of donor rats were flushed with and preserved in modified Euro-Collins solution at 4°C for 6 hr or 24 hr. The left lung was transplanted into recipient rats and reperfused for 1 hr. Lung injury was evaluated by the pulmonary blood flow ratios to the lung isografts, the weight gain of the isografts, and histological examination. Small portions of the lung isografts were excised and stained with an antibody specific for rat platelets. A scoring system was developed to semiquantitate the intensity of antibody staining (score 0-4). The recipient rats received oral administration of beraprost sodium (0.3 mg/kg) before lung transplantation. Control animals received no beraprost sodium. Results. In the 6-hr preservation study, administration of beraprost sodium significantly reduced the score for platelet accumulation (1.8±0.4 vs. 3.3±0.5, P<0.01). This observation was accompanied by a significantly decreased degree of preservation-reperfusion injury as evidenced by an increased blood flow ratio (13.7±2.6% vs. 4.5±3.6%, P<0.01) and a reduced weight gain (0.7±0.2 g vs. 1.1±0.2 g, P<0.01). Histological examination revealed severe capillary congestion in three of six cases in the control group, while no capillary congestion was observed in the beraprost group. In the 24-hr preservation study, no differences were seen in platelet accumulation scores or parameters of lung injury. Conclusion. Beraprost sodium, an antiplatelet agent, reduces platelet accumulation and preservation-reperfusion injury of lung transplants at 6 hr in this rat isograft model.
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