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), Vol. 6
- Country of Publication:
- United States
- Language:
- English
Similar Records
Onset of lipoprotein-supported steroidogenesis in differentiating granulosa cells of rats: cellular events involved in mediating FSH-enhanced uptake of low-density lipoproteins
Determinants of the uptake of very low density lipoprotein remnants by the perfused rat liver
Related Subjects
LIPOPROTEINS
UPTAKE
CAPILLARIES
CHOLESTEROL
DOUBLE LABELLING
ENDOTHELIUM
HAMSTERS
IODINE 125
LUNGS
RECEPTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LABELLING
LIPIDS
MAMMALS
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RESPIRATORY SYSTEM
RODENTS
STEROIDS
STEROLS
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques