Fig. 1.

Changes in left pulmonary blood flow (LPA; A) and left pulmonary vascular resistance (LPVR; B) before and after acute ductal constriction. Acute ducal constriction induces an initial increase in pulmonary blood flow and decrease in pulmonary vascular resistance. This is followed by active pulmonary vasoconstriction, resulting in a decrease in flow and increase in resistance. Pretreatment with PEG-SOD attenuated this response. N = 5 vehicle-treated lambs, n = 7 PEG-SOD-treated lambs. Values are means ± SD. *P < 0.05 vs. pre, †P < 0.05 vs. 30 min, ‡P < 0.05 between groups.