title: Circadian variation in platelet function in healthy volunteers.
abstract: Circadian variation in hemostatic factors may contribute to a higher frequency of cardiac events observed in the morning and with activity. Diurnal changes in these factors were investigated by measuring in vitro platelet aggregability in response to epinephrine and adenosine diphosphate together with beta-thromboglobulin and platelet factor 4 as indexes of in vivo platelet activation. Activation of coagulation was measured by thrombin-antithrombin III complexes and D-Dimers. Tests were performed in 9 normal healthy subjects. Circadian changes occurred in beta-thromboglobulin (p less than 0.05) and platelet factor 4 (p less than 0.06). Plasma levels of beta-thromboglobulin and platelet factor 4 were lowest with patients supine and resting at 7 and 8 A.M., and increased with activity, with peak levels achieved at 3 P.M. (p less than 0.01). Thrombin-antithrombin III complexes (p = 0.44), D-Dimer (p = 0.36) and in vitro platelet aggregability to adenosine diphosphate (p = 0.20) did not show diurnal variation. There was a trend toward circadian variation in vitro platelet aggregability to epinephrine, but these changes did not achieve statistical significance (p = 0.16). Circadian changes of in vivo release of beta-thromboglobulin and platelet factor 4 correlated to patient activity and not to the morning peaks in ischemic events. These data indicate that changes in platelet function and not in coagulation have a diurnal occurrence.
authors.affiliation: Heart and Vascular Institute, Henry Ford Hospital, Detroit, Michigan 48202.
authors.forename: S M
authors.initials: SM
authors.lastname: Jafri
authors.forename: M
authors.initials: M
authors.lastname: VanRollins
authors.forename: T
authors.initials: T
authors.lastname: Ozawa
authors.forename: E F
authors.initials: EF
authors.lastname: Mammen
authors.forename: A D
authors.initials: AD
authors.lastname: Goldberg
authors.forename: S
authors.initials: S
authors.lastname: Goldstein
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D000990:Antithrombin III / Q000032:analysis; D001792:Blood Platelets / Q000502:physiology*; D002118:Calcium / Q000097:blood; D002940:Circadian Rhythm; D004797:Enzyme-Linked Immunosorbent Assay; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D010447:Peptide Hydrolases / Q000032:analysis; D010974:Platelet Aggregation / Q000187:drug effects; D012016:Reference Values; D001620:beta-Thromboglobulin / Q000032:analysis
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C046193:antithrombin III-protease complex; D001620:beta-Thromboglobulin; C036309:fibrin fragment D; D000244:Adenosine Diphosphate; D000990:Antithrombin III; D010447:Peptide Hydrolases; D002118:Calcium; D004837:Epinephrine