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Calcium antagonists and low density lipoprotein receptors
R Paoletti1, F Bernini, R Fumagalli
1Institute of Pharmacological Sciences, University of Milan, Italy.
Annals of the New York Academy of Sciences
|January 1, 1988
Summary
Certain calcium antagonists, like verapamil and diltiazem, enhance LDL receptor activity, boosting cholesterol breakdown in human cells. This suggests a role in preventing atherosclerosis.
Area of Science:
- Biochemistry
- Pharmacology
- Cell Biology
Background:
- Low-density lipoprotein (LDL) metabolism is crucial for cellular lipid homeostasis.
- Calcium antagonists are a class of drugs with diverse pharmacological activities.
- The impact of different calcium antagonist types on LDL catabolism was previously unclear.
Purpose of the Study:
- To investigate the effect of various calcium antagonists on receptor-mediated LDL catabolism in human cells.
- To determine which types of calcium antagonists influence LDL uptake and metabolism.
Main Methods:
- Cultured human cells (fibroblasts, HepG2 hepatoma cells) were treated with different types of calcium antagonists.
- Receptor-mediated LDL uptake was measured.
- The effects of cycloheximide and alpha-amanitin were assessed to explore the mechanism.
Main Results:
- Calcium antagonists of Type I (verapamil-related) and Type III (diltiazem) significantly increased receptor-mediated LDL uptake.
- Calcium antagonists of Type II (nifedipine-related) and Type IV (flunarizine) showed no effect on LDL uptake.
- The stimulatory effect was dose-dependent and required new protein synthesis, as indicated by cycloheximide and alpha-amanitin experiments.
Conclusions:
- Specific calcium antagonists (Type I and III) stimulate LDL receptor activity in various human cells.
- This stimulation may contribute to the antiatherosclerotic effects of these drugs by improving lipid metabolism.
- Calcium antagonists might counteract lipid metabolism inhibition caused by calcium deposition in arterial walls.