[Experimental studies on changes of SOD activity levels and reperfusion injury after lung transplantation]

The purpose of this study is to evaluate the role of superoxide dismutase (SOD) in reperfusion injury after lung transplantation in mongrel dogs. Canine left lungs were used and three groups were studied. Group I underwent complete hilar stripping (n = 6). Group II underwent complete hilar stripping and was kept in warm ischemia for 60 min. by clamping left pulmonary artery and veins (n = 6). Group III underwent the same surgery as Group II and kept in warm ischemia for 120 min (n = 6). To evaluate the function of the lung, arterial blood gas, left total pulmonary resistance (ITPR) and lung wet to dry weight ratio (W/D ratio) were measured in transient contralateral pulmonary arterial occlusion periodically for 7 days after reperfusion. Also, plasma and bronchoalveolar lavage fluid (BALF) levels of SOD like activity, angiotensin converting enzyme (ACE) activity and ceruloplasmin were measured before operation and periodically after reventilation and reperfusion. Additionally, using dialyzer and electron spin resonance (ESR) spectrometry, plasma levels of extracellular SOD (EC-SOD) activity were measured. The results obtained were as follows. 1) In Group II and III, W/D ratio, ITPR and arterial blood gas were significantly increased in comparison with Group I. 2) Though there were no significant changes in the BALF levels of SOD like activity, ACE and ceruloplasmin and in the plasma levels of ACE and ceruloplasmin, the plasma level of SOD like activity rose 3 hours after reperfusion. 3) The plasma level of EC-SOD activity rose along with that of SOD like activity without any change in intra-cellular SOD levels. The above results suggest that EC-SOD plays an important role in cyto-protection against reperfusion injury after lung transplantation.