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In vitro interactions between low density lipoprotein from hyperapobetalipoproteinemic plasma and arterial wall
Objective:
To examine the interactions of low density lipoprotein-B (LDL-B) with proteoglycans (PG) in vitro.
Design:
The PG were isolated from human aortas, removed at autopsy by a combination of extraction with 4M guanidine-Tris buffer containing protease inhibitors and fractionation on a DEAE-Sephacel ion-exchange chromatography column. LDL and LDL-B from healthy or hyperapobetalipoproteinemic sera, respectively, were isolated by standard density flotation techniques followed by radioiodination. Radiolabelled lipoproteins (LP) were incubated with proteoglycans at 4 or 37 degrees C in a low ionic strength buffer with or without addition of polyethylene glycol (PEG) which was used to enhance precipitation of the resulting LP-PG complexes.
Main Results:
Data revealed that a specific ratio of LP to PG is a prerequisite for optimal interactions between these macromolecules. Further, it was observed that LDL-B forms fewer precipitable complexes than normal LDL at 4 degrees C. However, at physiological temperature or with the addition of PEG, precipitation of the two LDLs was equal.
Conclusion:
LDL and LDL-B showed equal reactivity with PG in terms of precipitable complexes.