The life cycle of a low-molecular-weight protein of surfactant (SP-C) in 3-day-old rabbits.
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.
Baritussio
A
A
Istituti di Medicina Interna, Università di Padova, Italy.
Benevento
M
M
Pettenazzo
A
A
Bruni
R
R
Santucci
A
A
Dalzoppo
D
D
Barcaglioni
P
P
Crepaldi
G
G
D000818:Animals; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D010713:Phosphatidylcholines / Q000378:metabolism; D011510:Proteolipids / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000378:metabolism*; D011817:Rabbits; D013997:Time Factors
D010713:Phosphatidylcholines; D011510:Proteolipids; D011663:Pulmonary Surfactants