title: Daily variations of platelet aggregation in relation to blood and plasma serotonin in diabetes.
abstract: The circadian rhythms of platelet aggregation in the whole blood and platelet rich plasma-PRP and plasma serotonin were studied in healthy volunteers (n = 10) and diabetic patients (type II diabetes mellitus n = 12). Platelet aggregation in the whole blood induced by collagen (2 micrograms/ml), ADP (10 microM), arachidonic acid (0.5 mM) and epinephrine (10 microM), and in PRP induced by collagen (2 micrograms/ml), ADP (5 microM), arachidonic acid (250 microM), epinephrine (10 microM) and serotonin-5-HT (1 microM) was measured at 7:30, 11:30, 17:00, 23:00, 4:00 and 7:00. In healthy subjects collagen- and ADP-induced platelet aggregation in the whole blood was significantly lower at 23:00 and 4:00 when compared to values at 7:30. In PRP normal and diabetic platelet response was the lowest during the night. Diabetic platelets exhibited an enhanced response to 5-HT starting from 17:00 until 4:00 when compared to 7:30. 5-HT-induced platelet aggregation was found to be significantly higher throughout the study in DM patients over controls in parallel to plasma 5-HT. In healthy volunteers plasma 5-HT was higher at 17:00 when compared to baseline values, whereas in DM patients plasma 5-HT was elevated starting from 17:00 until 4:00. An enhanced response of diabetic platelets to 5-HT together with elevated plasma 5-HT levels may contribute, at least partly, to the pathogenesis of diabetic vasculopathy and 5HT2 receptor blockers may be of value in DM patients.
authors.affiliation: Physiology Department, Hamamatsu University School of Medicine, Shizuoka, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Malyszko
authors.forename: T
authors.initials: T
authors.lastname: Urano
authors.forename: R
authors.initials: R
authors.lastname: Knofler
authors.forename: A
authors.initials: A
authors.lastname: Taminato
authors.forename: T
authors.initials: T
authors.lastname: Yoshimi
authors.forename: Y
authors.initials: Y
authors.lastname: Takada
authors.forename: A
authors.initials: A
authors.lastname: Takada
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D016718:Arachidonic Acid / Q000494:pharmacology; D002940:Circadian Rhythm / Q000502:physiology*; D003094:Collagen / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000097:blood*
chemical_list: D016718:Arachidonic Acid; D012701:Serotonin; D000244:Adenosine Diphosphate; D003094:Collagen; D004837:Epinephrine