Pulmonary Edema after Pulmonary Artery Occlusion and Reperfusion

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Abstract
We examined the basis of reperfusion-induced pulmonary edema produced by pulmonary artery occlusion and subsequent reperfusion. After a 24-h period of occlusion of a rabbit pulmonary artery followed by a 2-h period of reperfusion, the lungs were removed from the animal and perfused with a 0.5 g% Ringer''s-albumin solution. An increase in lungs weight was observed within 60 min compared with control lungs (i.e., lungs subjected to pulmonary arterial occlusion but not reperfusion) (p < 0.05). Shorter periods of occlusion (6 or 12 h) did not result in edema, which suggests that a period of ischemia was required for the reperfusion-induced pulmonary edema. The extravascular lung water content also increased in the contralateral lung (i.e., the lung not subjected to pulmonary arteial occlusion and reperfusion). The capillary filtration coefficient increased in reperfused lungs compared with controls (p < 0.05), indicating an increase in lung vascular premeability following reperfusion. Infusion of allopurinol (a xanthine oxidase inhibitor) and superoxide dismutase during the reperfusion period prevented the increases in lung weight and vascular premeability; infusion of catalase was ineffective. We conclude that pulmonary reperfusion following pulmonary artery occlusion increases pulmonary vascular premeability, which is mediated by the generated of oxidants.