Adenosine 5'-diphosphate as a factor in platelet aggregation induced by human plasma remnant lipoproteins

Abby R. Saniabadi, Kazuo Umemura, Yasuhiro Suzuki, Kazunao Kondo, Yasuhiko Ikeda, Masakazu Adachi, Mitsuyoshi Nakashima

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The action of lipoprotein lipase on chylomicrons (CM) and very low density lipoproteins (VLDL) produces remnant lipoproteins (RLP) which are rich in triglycerides, cholesterol and apolipoprotein E (apo E). Apo E serves as a ligand for uptake of RLP by macrophages, platelets, endothelial cells and other cells expressing the LDL-receptor or the remnant receptor, thus having a major role in the clearance of plasma cholesterol and triglycerides, but at the same time, uptake of apo E-bearing RLP can profoundly alter the physiology of these cells and promote atherosclerosis. Like RLP, blood platelets also have roles in atherosclerosis and thrombosis, hence it is likely that RLP influence platelet activity as well. RLP derived from normal human plasma VLDL and CM were prepared using two monoclonal antibodies, anti- apo B-100 (JI-H) and anti-apo A-I (H-12) coupled to Sepharose 4B gel to form an immunoaffinity column. Lipoproteins containing apo B-100 including VLDL and LDL adsorb to (JI-H)-gel, while CM and HDL with apo A-I adsorb to (H- 12)-gel. The particles in the unbound fraction (RLP) are rich in apo B-48, apo E and apo B-100 containing particles with multiple molecules of apo E. The RLP fraction with a total triglyceride of 14 ± 3.2 mg/ml; cholesterol, 0.39 ± 0.1 mg/ml and protein, 0.78 ± 0.24 mg/ml (n = 19) was added to aliquots of blood of man, rabbits, guinea pigs, mice, and rats at protein equivalents of 0.98 to 78 μg/ml blood and agitated gently at 37 °C for 40 sec. Platelet aggregation was measured as a fall in single platelet count. RLP induced aggregation of platelets in man (p < 0.005) rabbit (p < 0.0005), guinea pig (p < 0.002) and mouse (p < 0.0001), but no RLP induced platelet aggregation was observed in the rat blood. Scanning electron microscopy revealed that in the presence of RLP, platelets had adhered to and formed aggregates on red cells. The platelet response to RLP was inhibited by apyrase known to scavenge ADP, by 5 μM 2-chloroadenosine, a platelet ADP receptor antagonist and by 3.4 μM cilostazol, a phosphodiesterase type III inhibitor known to raise cyclic AMP level in platelets. It is thought that RLP cause leakage of ADP from red cells which then mediates platelet aggregation.

Original languageEnglish
Pages (from-to)1065-1074
Number of pages10
JournalLife Sciences
Volume63
Issue number12
DOIs
Publication statusPublished - 14-08-1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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