Preservation of intraalveolar surfactant in a rat lung ischaemia/reperfusion injury model

Ischaemia/reperfusion (I/R) injury, a major problem in clinical lung transp lantation, is associated,vith surfactant dysfunction, The present study aim ed to test the hypothesis that preservation related improvements in post-is chaemic lung function are associated with improved ultrastructural preserva tion of pulmonary surfactant. Rat lungs were flush perfused with modified Euro-Collins solutions (ECS), s tored for 2 h at 4 degrees C, and reperfused for 40 min, Lungs were preserv ed with conventional (ECS 115: 115 mmol.L-1 K+), medium-K+ (ECS 40: 40 mmol .L-1 K+), or low-K+ (ECS 10: 10 mmol.L-1 K+) ECS, Functional parameters wer e monitored during reperfusion (n=10 per group). After reperfusion, left lu ngs were prepared for electron microscopical and stereological analysis of surfactant (n=5 per group). In all three experimental groups notable I/R injury developed which was low est in ECS 40 as indicated by significantly less intraalveolar oedema, high er perfusate oxygenation, and lower peak inspiratory pressure, This was ass ociated with a significantly superior preservation of the ultrastructure of the surface active surfactant subtype tubular myelin in ECS 40 compared wi th ECS 115 and ECS 10, Stereological analysis revealed that the relative am ount of tubular myelin was highest in ECS 40 (mean+/-SEM; 6.+/-0.8%) compar ed with ECS 115 (3.0+/-1.0%) and ECS 10 (2.7+/-1.6%). Analysis of surfactant in its natural location within the organ showed that the severity of ischaemia/reperfusion injury correlates with differences i n intraalveolar surfactant composition. Improved post-ischaemic respiratory function achieved by medium-Ki Euro-Collins solution is associated with su perior ultrastructural preservation of tubular myelin, It is concluded that the integrity of surface active tubular myelin represents an important cri terion for the assessment of lung preservation quality.