Folkesson H G, Norlin A, Wang Y, Abedinpour P, Matthay M A
Department of Animal Physiology, Lund University, S-223 62 Lund, Sweden.
J Appl Physiol (1985). 2000 Feb;88(2):416-24. doi: 10.1152/jappl.2000.88.2.416.
The in vivo effect of 48-h glucocorticoid and thyroid hormone 3,3', 5-triiodine-L-thyronine (T(3)) pretreatment on alveolar epithelial fluid transport was studied in adult rats. An isosmolar 5% albumin solution was instilled, and alveolar fluid clearance was studied for 1 h. Compared with controls, dexamethasone pretreatment increased alveolar fluid clearance by 80%. T(3) pretreatment stimulated alveolar fluid clearance by 65%, and dexamethasone and T(3) had additive effects (132%). Propranolol did not inhibit alveolar fluid clearance in either group, indicating that stimulation was not secondary to endogenous beta-adrenergic stimulation. With the use of bromodeoxyuridine in vivo labeling, there was no evidence of cell proliferation. Alveolar fluid clearance was partially inhibited by amiloride in all groups. Fractional amiloride inhibition was greater in dexamethasone- and dexamethasone-plus-T(3)-pretreated rats than in control animals, but less in T(3)-pretreated rats. In summary, pretreatment with dexamethasone, T(3), or both in combination upregulate in vivo alveolar fluid clearance similarly to short-term beta-adrenergic stimulation. The effects are mediated partly by increased amiloride-sensitive Na(+) transport, because the stimulated alveolar fluid clearance was more amiloride sensitive than in control rats. These observations may have clinical relevance because glucocorticoid therapy is commonly used with acute lung injury.
研究了成年大鼠体内48小时糖皮质激素和甲状腺激素3,3',5-三碘-L-甲状腺原氨酸（T3）预处理对肺泡上皮液体转运的影响。滴注等渗5%白蛋白溶液，并研究1小时的肺泡液体清除率。与对照组相比，地塞米松预处理使肺泡液体清除率提高了80%。T3预处理使肺泡液体清除率提高了65%，地塞米松和T3具有相加作用（132%）。普萘洛尔在两组中均未抑制肺泡液体清除率，表明这种刺激并非内源性β-肾上腺素能刺激的继发效应。使用溴脱氧尿苷体内标记，没有细胞增殖的证据。所有组中，氨氯吡咪均部分抑制肺泡液体清除率。地塞米松预处理组和地塞米松加T3预处理组中氨氯吡咪的抑制分数高于对照动物，但T3预处理组中较低。总之，地塞米松、T3或两者联合预处理在体内上调肺泡液体清除率的作用与短期β-肾上腺素能刺激相似。这些作用部分由氨氯吡咪敏感的Na+转运增加介导，因为刺激后的肺泡液体清除率比对照大鼠对氨氯吡咪更敏感。这些观察结果可能具有临床相关性，因为糖皮质激素治疗常用于急性肺损伤。
