Tsutomu Sakuma1,*, Mieko Hida2, Yoshihiro Nambu2,
Kazuhiro Osanai2, Hirohisa Toga2, Keiji Takahashi2,
Nobuo Ohya2, Masao Inoue3 and Yoh Watanabe1
1Department of Thoracic Surgery, 2Department of Pulmonary Medicine, and 3Radioisotope Center, Division of Core Facility, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
*Corresponding author. FAX: +81-76-286-1207
Abstract: Because it was still uncertain whether a stimulation of b1-adrenoceptors accelerated alveolar fluid clearance in hyperoxic lung injury, the effect of denopamine, a selective b1-adrenergic agonist, on alveolar fluid clearance was determined in rats exposed to 93% oxygen for 48 and 56 h. Alveolar fluid clearance was measured by the progressive increase in the concentration of Evans blue labeled albumin instilled into the alveolar spaces over 1 h at 37íC in isolated rat lungs. The principle results were as follows: 1) Although lung water volume increased in rats exposed to hyperoxia for 48 and 56 h, basal alveolar fluid clearance did not change for up to 56 h; 2) Denopamine increased alveolar fluid clearance in rats exposed to hyperoxia as well as in rats without exposure to hyperoxia; 3) Denopamine primarily increased amiloride-insensitive alveolar fluid clearance in rats exposed to hyperoxia; 4) The potency of denopmaine was similar to that of terbutaline, a selective b2-adrenergic agonist. In summary, denopamine is a potent stimulator of alveolar fluid clearance in rats exposed to hyperoxia.
Keywords: Pulmonary edema, Lung injury, Sodium transport, Alveolar epithelium
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