Beta2-agonists have been shown to increase alveolar fluid reabsorption, and at least part of their effect depends on active
sodium transport from the alveolus into the epithelial cell by the
amiloride-sensitive
epithelial sodium channel (ENaC). Few data exist on their effect in the injured lung. The authors therefore investigated the effect of intrabronchially administered
terbutaline pretransplantation by measuring outcome 1 day after experimental donor
lung transplantation with severe injury due to prolonged
ischemia. Orthotopic single left-sided lung allotransplantation was performed in female rats (Wistar to Wistar) after a total ischemic time of 20 hours. Graft PaO2/FiO2 in 6 recipients treated with 10(-4) M
terbutaline in 500 microL NaCl 0.9% was superior 24 hours after
transplantation, with a PaO2 of 329 (111 [SD]) mm Hg versus 5 vehicle controls with 44 (15) mm Hg (P = .002). The beneficial effect of 10(-4) M
terbutaline was abrogated by 10(-4) M of the
sodium channel blocker amiloride to 71 (34) mm Hg in 3 recipients (P = .028 versus
terbutaline 10(-4) M). Ten recipients receiving 10(-5) M
terbutaline in 500 microL NaCl 0.9% showed inconsistent improvements of gas exchange, with a PaO2 of 158 (+/- 153) mm Hg (P = .058).
Terbutaline at a high dose significantly improved the transplanted rat lung function at 24 hours after
transplantation. Part of it may be via activating epithelial
sodium transport, thus suggesting an important role of alveolar fluid transport in such a model of
acute lung injury.