Uptake of low density lipoproteins by the hamster lung. Interactions with capillary endothelium
The mechanism by which the circulating low density lipoproteins (LDL) contribute to the lung surfactant cholesterol was investigated by perfusing the hamster lung in situ with LDL either radiolabeled or coupled to gold, or both. Part of (/sup 125/I)-LDL and (/sup 3/H)-cholesterol LDL were taken up by a specific process which was time- and concentration-dependent and reached saturation within 20 to 30 min of perfusion. Competition experiments and removal of receptor-bound LDL by heparin suggested that about 50% of LDL uptake is receptor-independent. Experiments using double labeled LDL showed a preferential uptake of /sup 3/H-cholesterol versus /sup 125/I by the lung both in situ and in vivo. LDL-gold particles (LDL-Au), recirculated through the isolated lung, bound to the endothelial luminal plasma membrane and to features potentially involved in receptor-mediated endocytosis (coated pits, coated vesicles, lysosomelike structures) and in transcytosis (plasmalemmal vesicles). The results suggest that LDL uptake by the lung takes place by both receptor-mediated and receptor-independent mechanisms. Cholesterol may be in part transferred to the lung without the apoprotein moiety; the alveolar capillary endothelium appears to be the first monitor of this complex process.
- Research Organization:
- Institute of Cellular Biology and Pathology, Bucharest, Romania
- OSTI ID:
- 6846802
- Journal Information:
- Am. Rev. Respir. Dis.; (United States), Journal Name: Am. Rev. Respir. Dis.; (United States) Vol. 6; ISSN ARDSB
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CAPILLARIES
CARDIOVASCULAR SYSTEM
CHOLESTEROL
DAYS LIVING RADIOISOTOPES
DOUBLE LABELLING
ELECTRON CAPTURE RADIOISOTOPES
ENDOTHELIUM
HAMSTERS
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LABELLING
LIPIDS
LIPOPROTEINS
LUNGS
MAMMALS
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RECEPTORS
RESPIRATORY SYSTEM
RODENTS
STEROIDS
STEROLS
TISSUES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
UPTAKE
VERTEBRATES