title: High glucose levels enhance platelet activation: involvement of multiple mechanisms.
abstract: Diabetes mellitus (DM) and hyperglycaemia are associated with platelet activation. The present study was designed to investigate how high glucose levels influence platelet function. Fasting human blood was incubated with different concentrations of D-glucose (5, 15 and 30 mmol/l) and other sugars without or with in vitro stimuli. Platelet activation was monitored by whole blood flow cytometry. High glucose levels enhanced adenosine diphosphate (ADP)- and thrombin receptor-activating peptide (TRAP)-induced platelet P-selectin expression, and TRAP-induced platelet fibrinogen binding. Similar effects were seen with 30 mmol/l L-glucose, sucrose and galactose. Hyperglycaemia also increased TRAP-induced platelet-leucocyte aggregation. Protein kinase C (PKC) blockade did not counteract the enhancement of platelet P-selectin expression, but abolished the enhancement of TRAP-induced platelet fibrinogen binding by hyperglycaemia. Superoxide anion scavenging by superoxide dismutase (SOD) attenuated the hyperglycaemic enhancement of platelet P-selectin expression, but did not counteract the enhancement of TRAP-induced platelet fibrinogen binding. Hyperglycaemia did not alter platelet intracellular calcium responses to agonist stimulation. Blockade of cyclo-oxygenase (COX), phosphotidylinositol-3 (PI3) kinase, or nitric oxide synthase, or the addition of insulin did not influence the effect of hyperglycaemia. In conclusion, high glucose levels enhanced platelet reactivity to agonist stimulation through elevated osmolality. This occurred via superoxide anion production, which enhanced platelet P-selectin expression (secretion), and PKC signalling, which enhanced TRAP-induced fibrinogen binding (aggregablity).
authors.affiliation: Department of Medicine, Clinical Pharmacology Unit, Karolinska University Hospital (Solna), Stockholm, Sweden.
authors.forename: Dzana
authors.initials: D
authors.lastname: Sudic
authors.forename: Masoud
authors.initials: M
authors.lastname: Razmara
authors.forename: Mikael
authors.initials: M
authors.lastname: Forslund
authors.forename: Qiushang
authors.initials: Q
authors.lastname: Ji
authors.forename: Paul
authors.initials: P
authors.lastname: Hjemdahl
authors.forename: Nailin
authors.initials: N
authors.lastname: Li
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000097:blood; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D005434:Flow Cytometry; D005690:Galactose / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D019007:P-Selectin / Q000097:blood; D010446:Peptide Fragments / Q000494:pharmacology; D015539:Platelet Activation / Q000187:drug effects* / Q000502:physiology; D010974:Platelet Aggregation / Q000187:drug effects; D011493:Protein Kinase C / Q000502:physiology; D013395:Sucrose / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
chemical_list: D019007:P-Selectin; D010446:Peptide Fragments; D013481:Superoxides; C086309:thrombin receptor peptide SFLLRNP; D013395:Sucrose; D000244:Adenosine Diphosphate; D005340:Fibrinogen; D011493:Protein Kinase C; D005947:Glucose; D002118:Calcium; D005690:Galactose