Effect of denopamine on alveolar fluid clearance in hypoxic rat lungs

AIM:To study the effect of β1-adrenergic agonist on alveolar fluid clearance in hypoxic rat lungs. METHODS: Rats were exposed to 10% oxygen. Alveolar fluid clearance (AFC) and lung water content (TLW) were calculated in rats exposed to hypoxia for 24 h and 48 h. Isotonic 5% albumin in solutions with different pharmacological agents were instilled into the distal airways in the hypoxia exposed and room air-exposed rat lungs, and the AFC was examined. RESULTS: As compared with the room air-exposed rats (17.50%±2.66%), AFC in the rats exposed to 10% oxygen was not decreased (18.70%±3.19%), AFC in the rats exposed to 10% oxygen for 48 h was decreased (8.59%±2.60%). Denopamine, a β1-adrenergic agonist, increased AFC significantly in the rats exposed to room air and hypoxia. The potency of 10-5 mol/L denopamine was similar to that of 10-5mol/L terbutaline. The denopamine effect was partly blocked by inhibitors of sodium transport amiloride and ouabain (AFC were 11.80%±2.79% and 8.53%±2.17%). CONCLUSION: Denopamine, a selective β1-adrenergic agonist, stimulates alveolar fluid clearance in rats exposed to hypoxia through the active sodium transport, and may have therapeutical effect on pulmonary edema after acute lung injury.