title: Impaired responsiveness of platelets to epinephrine due to α2A adrenoreceptor deficiency in Male Chinese.
abstract: Epinephrine is known as a weak, but important, agonist for platelet activation. It has been reported that the responsiveness of platelets to epinephrine was markedly impaired in 6% of Caucasians and in 16% of Japanese. The purpose of this study was to screen and characterize this abnormality in healthy Taiwanese Chinese volunteers. We used aggregometry, flow cytometry and platelet function analyzer (PFA)-100 system to assess in 50 healthy male volunteers the responsiveness of platelets to epinephrine stimulation. Using α2A adrenoceptor antagonist BRL44408 maleate competition and a [(3)H]yohimbin binding assay, we evaluated α2A adrenoceptors on platelets. The aggregation of platelets after stimulation with 10 μM of epinephrine indicated two distinct groups of study participants: 24 (48.0%) good- and 26 (52.0%) impaired-responders to epinephrine. Flow cytometric analysis of platelets after stimulated with 1 μM epinephrine showed that glycoprotein (GP) IIb/IIIa and P-selectin expression of epinephrine good- and impaired-responders were 27.1 ± 11.0% vs. 9.9 ± 5.4% (p = 0.003) and 12.2 ± 6.2% vs. 3.6 ± 3.5% (p < 0.001), respectively. The PFA-100 system showed that epinephrine-impaired-responders had a longer collagen-epinephrine induced closure time. Good-responder platelets incubated with BRL44408 maleate had an impaired response to epinephrine stimulation. [(3)H]yohimbine binding studies showed fewer α2A adrenoreceptors on the platelets of epinephrine-impaired-responders than on those of good-responders. The prevalence of impaired responsiveness to epinephrine was high and probably due to α2A adrenoreceptor deficiency in male Taiwanese Chinese.
authors.affiliation: a Department of Laboratory Medicine , E-Da Hospital/I-Shou University , Kaohsiung , Taiwan .|b Department of Medical Research , E-Da Hospital/I-Shou University , Kaohsiung , Taiwan .
authors.forename: Tsun-Mei
authors.initials: TM
authors.lastname: Lin
authors.affiliation: c Department of Pathology , College of Medicine, National Cheng Kung University , Tainan , Taiwan .|d Section of Hematology/Oncology, Department of Internal Medicine , College of Medicine, National Cheng Kung University , Tainan , Taiwan , and.
authors.forename: Jih-Shyan
authors.initials: JS
authors.lastname: Lin
authors.affiliation: c Department of Pathology , College of Medicine, National Cheng Kung University , Tainan , Taiwan .|d Section of Hematology/Oncology, Department of Internal Medicine , College of Medicine, National Cheng Kung University , Tainan , Taiwan , and.
authors.forename: Jen-Yu
authors.initials: JY
authors.lastname: Tseng
authors.affiliation: e Department of Internal Medicine , College of Medicine, National Cheng Kung University , Tainan , Taiwan.
authors.forename: Shang-Yin
authors.initials: SY
authors.lastname: Wu
authors.affiliation: e Department of Internal Medicine , College of Medicine, National Cheng Kung University , Tainan , Taiwan.
authors.forename: Tsai-Yun
authors.initials: TY
authors.lastname: Chen
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology*; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology*; D000328:Adult; D044466:Asian People; D001681:Biological Assay; D001692:Biological Transport; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D015870:Gene Expression; D006801:Humans; D008297:Male; D008298:Maleates / Q000494:pharmacology*; D019007:P-Selectin / Q000097:blood / Q000235:genetics; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000235:genetics / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000172:deficiency* / Q000235:genetics; D014316:Tritium; D015016:Yohimbine / Q000378:metabolism
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D008298:Maleates; D019007:P-Selectin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D018341:Receptors, Adrenergic, alpha-2; D014316:Tritium; D015016:Yohimbine; D003094:Collagen; D004837:Epinephrine
keywords: epinephrine; flow cytometry; platelet aggregometry; α2A adrenoreceptor