Fisher A B, Dodia C, Chander A
Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104-6068.
Am J Physiol. 1989 Oct;257(4 Pt 1):L248-52. doi: 10.1152/ajplung.1989.257.4.L248.
This study evaluated the effect of known secretagogues for lung surfactant on the uptake of phospholipid from the aveolar space. Synthetic liposomes containing tracer [choline-methyl-3H]dipalmitoyl phosphatidylcholine (DPPC) were instilled endotracheally in anesthetized rats. Lungs were then isolated and perfused under control conditions or with addition of terbutaline (0.1 mM), ATP (1 mM), or a phorbol ester, tradecanoyl phorbol acetate (TPA, 30 ng/ml). Uptake of liposomes was defined as lavage-resistant accumulation of radioactivity in the lung. Uptake at 2 h was 18.2 +/- 0.93% of instilled radioactivity per minute (mean +/- SE, n = 4) under control conditions and was increased by 56-82% in the presence of each of the agonists (P less than 0.05). At 5 min after addition of terbutaline, uptake was unchanged but secretion of phosphatidylcholine (PC) into the alveolar space was significantly stimulated. Internalized diphosphatidylcholine was degraded to aqueous soluble metabolites and also converted to PC containing an unsaturated fatty acid, and this metabolism was significantly stimulated in the presence of each of the secretagogues. These results indicate that known secretagogues for surfactant increase uptake and metabolism of phospholipid, suggesting linkage of these processes in a physiologically regulated surfactant cycle.
本研究评估了已知的肺表面活性物质促分泌剂对肺泡腔内磷脂摄取的影响。将含有示踪剂[胆碱 - 甲基 - ³H]二棕榈酰磷脂酰胆碱（DPPC）的合成脂质体经气管内注入麻醉大鼠体内。然后分离肺脏，并在对照条件下或添加特布他林（0.1 mM）、ATP（1 mM）或佛波酯十四酰佛波醇乙酸酯（TPA，30 ng/ml）的情况下进行灌注。脂质体的摄取定义为肺内放射性物质的灌洗抗性积累。在对照条件下，2小时时的摄取量为每分钟注入放射性物质的18.2±0.93%（平均值±标准误，n = 4），在每种激动剂存在的情况下摄取量增加了56 - 82%（P＜0.05）。添加特布他林后5分钟，摄取量未改变，但磷脂酰胆碱（PC）向肺泡腔的分泌受到显著刺激。内化的二磷脂酰胆碱降解为水溶性代谢产物，也转化为含有不饱和脂肪酸的PC，并且在每种促分泌剂存在的情况下这种代谢受到显著刺激。这些结果表明，已知的表面活性物质促分泌剂可增加磷脂的摄取和代谢，提示这些过程在生理调节的表面活性物质循环中存在联系。
