Protective agents used as additives in University of Wisconsin solution to promote protection against ischaemia-reperfusion injury in rat lung

1. An intervention to reduce ischaemia-reperfusion lung injury will be an important advance in transplant medicine. Although the mechanisms associated with producing ischaemia-reperfusion endothelial injury have not been completely elucidated, many of the injury mediators have been studied in detail. While no single pharmacological therapy is likely to be totally effective in eliminating this complex injury, we have developed a mixture of agents that are known to block pathways involved in producing ischaemia-reperfusion-associated lung vascular injury. 2. The present study modified University of Wisconsin solution (UW) by adding one of the protective agents prostaglandin E-1 (PGE(1)), dexamethasone (Dex) or dibutyryl cAMP (Bt(2)-cAMP), or a combination of these, to the perfusate of rat lungs exposed to 4 h of cold ischaemia followed by 1 h of reperfusion. Nine modified UW solutions were stud led : (1) UW + Dex, (2) UW + PGE(1), (3) UW + Bt(2)-cAMP, (4) UW + Dex x 3, (5) UW + PGE(1) x 3, (6) UW + Bt(2)-cAMP x 3, (7) UW + Dex + PGE(1), (8) UW + Dex + Br-2-cAMP, (9) UW + PGE(1) + Bt(2)-cAMP. These solutions were utilized in individual experiments to assess haemodynamic changes, lung weight gain, the capillary filtration coefficient (K-fc) and pathology in all lungs. 3. The results indicate that lung weight gain and K-fc values were significantly lower than with UW alone in groups 1, 2 and 3, which contained only one additional protective agent. In groups 4, 5 and 6, which contain three times the concentration of each protective agent, both K-fc and lung weight gain were similar to those measured in groups 1,2 and 3, i.e. lungs were protected but the protection was not dose dependent. in groups 7, 8 and 9, which contained two protective agents, lung weight gain and K-fc were greatly reduced compared with UW alone. Histopathological studies showed similar decreases in the injury profiles of lungs. 4. Although UW contains several antioxidant protective agents such as allopurinol and glutathlone, it did not provide effective protection in our ischaemia-reperfusion lung injury model. UW modified with an additive of PGE(1), Dex or Bt2-cAMP attenuated ischaemia-reperfusion injury. Furthermore, UW containing two of these protective agents augmented the protection. Among the modified solutions, it appears that UW + PGE(1) + Bt(2)-cAMP protects the lungs to a greater extent than all other solutions used in our study. We suggest that preservation solutions containing PGE(1)-Bt(2)-cAMP will provide additional protective effects to organs stored for transplantation.