Bronchial and reverse pulmonary venous blood flow protect the lung from ischemia-reperfusion injury

We used an intact in vivo canine model of pulmonary ischemia-reperfusion injury to evaluate whether the bronchial circulation or reverse pulmonary venous blood flow would protect the lung from injury during 2 h of unilateral pulmonary arterial (PA) occlusion and lung deflation. Serial measurements of regional extravascular density and transcapillary protein flux were made after reperfusion by using the quantitative imaging technique of positron emission tomography. Twenty-one animals were divided into four experimental groups. In all experimental groups, the left PA was clamped and the left lung was allowed to collapse and remain unventilated for a period of 2 h. In addition, in group I (n = 5) the left bronchial circulation was disrupted and the left pulmonary veins were clamped, in group II (n = 5) the bronchial circulation and the pulmonary veins were left intact, in group III (n = 6) the bronchial circulation was left intact but the pulmonary veins were clamped, and in group IV (n = 5) the bronchial circulation was disrupted but the pulmonary veins remained patent. The rate of protein flux in the left lung was increased only in group I (complete ischemia with lung deflation) [mean 195 x 10(-4) min-1 (range 85-453 x 10(-4) min-1) at 0.25 h and 114 x 10(-4) min-1 (range 22-200 x 10(-4) min-1) at 3 h] after reventilation and PA reperfusion (normal = 49 +/- 31 x 10(-4) min-1). Extravascular density increased significantly from 0.25 to 3 h only in group I.(ABSTRACT TRUNCATED AT 250 WORDS)