Increased vascular permeability in the adult respiratory distress syndrome is due in part to toxic oxygen metabolites. In the present study, we produced lung injury in the isolated rabbit lung with hydrogen peroxide (H2O2) and examined its prevention with isoproterenol. Pulmonary arterial pressure (Ppa) and the fluid filtration coefficient (Kf) were measured as indices of lung injury. Rabbits were divided into two groups, and 7 mmol/1 H2O2 was administered in both groups. In one group, isoproterenol (2 ug/ml) was administered 10 min before H2O2 injury. Ppa increased transiently after H2O2 administration in the control group but was unchanged in the isoproterenol group. Kf was significantly increased by H2O2 administration in the control group but not in the isoproterenol group. We conclude that H2O2 increases pulmonary vascular permeability and that isoproterenol may protect against H2O2-induced pulmonary injury.
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