Baritussio A, Benevento M, Pettenazzo A, Bruni R, Santucci A, Dalzoppo D, Barcaglioni P, Crepaldi G
Istituti di Medicina Interna, Università di Padova, Italy.
Biochim Biophys Acta. 1989 Nov 6;1006(1):19-25. doi: 10.1016/0005-2760(89)90318-4.
To clarify the metabolic cycle of a low-molecular-weight protein of surfactant (SP-C), we obtained alveolar surfactant from 3 day old rabbits killed 24 h after the tracheal administration of 32P or L-[35S]methionine (donors). Aliquots of this naturally labelled surfactant were administered into trachea to 3-day-old rabbits (recipients) which were killed after 1 min or 3, 8 or 24 h. We then analyzed the radioactivity associated with SP-C and with saturated phosphatidylcholine in fractions of lung lavage fluid and in lung homogenate. We found that alveolar SP-C is turned over faster than saturated phosphatidylcholine, that alveolar macrophages do participate in the removal of SP-C and that SP-C does not enter the fraction of alveolar surfactant that remains unsedimented after ultracentrifugation. Considering the whole lung, SP-C and saturated phosphatidylcholine are turned over at a comparable speed.
为阐明表面活性剂低分子量蛋白（SP-C）的代谢循环，我们从气管内给予³²P或L-[³⁵S]甲硫氨酸（供体）24小时后处死的3日龄兔获取肺泡表面活性剂。将这种天然标记的表面活性剂等分试样经气管给予3日龄兔（受体），1分钟或3、8或24小时后处死。然后我们分析了肺灌洗液和肺匀浆组分中与SP-C和饱和磷脂酰胆碱相关的放射性。我们发现肺泡SP-C的周转比饱和磷脂酰胆碱快，肺泡巨噬细胞确实参与了SP-C的清除，并且SP-C不会进入超速离心后仍未沉淀的肺泡表面活性剂组分。就整个肺而言，SP-C和饱和磷脂酰胆碱以相当的速度周转。
