Clearance of SP-C and recombinant SP-C in vivo and in vitro.
Surfactant protein (SP) C metabolism was evaluated in vivo by measurements of the clearance of bovine native SP-C (nSP-C) and a recombinant SP-C (rSP-C) in rabbits and mice and in vitro by the uptake into MLE-12 cells. rSP-C is the 34-amino acid human sequence with phenylalanine instead of cysteine in positions 4 and 5 and isoleucine instead of methionine in position 32. Alveolar clearances of iodinated SP-C and rSP-C after tracheal instillation were similar and slower than those for dipalmitoyl phosphatidylcholine (DPC) in the rabbit. nSP-C and rSP-C were cleared from rabbit lungs similarly to DPC, each with a half-life (t1/2) of approximately 11 h. In mice, the clearance of rSP-C from the lungs was slower (t1/2 28 h) than the clearance of DPC (t1/2 12 h). Liposome-associated dinitrophenyl-labeled rSP-C was taken up by MLE-12 cells, and the uptake was inhibited by excess nSP-C. The pattern of inhibition of dinitrophenyl-rSP-C uptake by SP-B, but not by SP-A, was similar to that previously reported for nSP-C. Clearance kinetics of nSP-C were similar to previous measurements of pulmonary clearance of SP-B in rabbits and mice. rSP-C has clearance kinetics and uptake by cells similar to those of nSP-C.
Ikegami
M
M
Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
Horowitz
A D
AD
Whitsett
J A
JA
Jobe
A H
AH
D000818:Animals; D002417:Cattle; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism; D006207:Half-Life; D007700:Kinetics; D008168:Lung / Q000378:metabolism; D051379:Mice; D011510:Proteolipids / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011650:Pulmonary Alveoli / Q000378:metabolism; D011663:Pulmonary Surfactants / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011817:Rabbits; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000493:pharmacokinetics; D007507:Therapeutic Irrigation; D014132:Trachea / Q000378:metabolism
D011510:Proteolipids; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins