TERBUTALINE STIMULATES ALVEOLAR FLUID RESORPTION IN HYPEROXIC LUNG INJURY

Alveolar fluid resorption occurs by active epithelial sodium transport and is accelerated by terbutaline in healthy lungs. We investigated t he effect of terbutaline on the rate of alveolar fluid resorption from rat lungs injured by hyperoxia. Rats exposed to >95% O-2 for 60 h, su fficient to increase wet-to-dry lung weight and cause alveolar edema, were compared with air-breathing control rats. After anesthesia, the a nimals breathed 100% O-2 for 10 min through a tracheostomy. Ringer sol ution was instilled into the alveoli, and the steady-state rate of vol ume resorbed at 6 cmH(2)O pressure was measured via a pipette attached to the tracheostomy tubing. Ringer solution in some animals contained terbutaline (10(-3) M), ouabain (10(-3) M), or both. Normoxic animals resorbed 49 +/- 6 mu l . kg(-1). min(-1); ouabain reduced this by 39% , whereas terbutaline increased the rate by 75%. The effect of terbuta line was blocked by ouabain. Hyperoxic animals absorbed 78 +/- 9 mu l . kg(-1). min(-1); ouabain reduced this by 44%. Terbutaline increased the rate by a mean of 39 mu l . kg(-1). min(-1), similar to the absolu te effect seen in the normoxic group, and this was blocked by ouabain. Terbutaline accelerates fluid resorption from both normal and injured rat lungs via its effects on active sodium transport.