title: Epinephrine induced platelet aggregation in rat platelet-rich plasma.
abstract: Epinephrine at even high concentrations neither caused shape change nor aggregation of rat platelets. However, epinephrine induced aggregation in the presence of low (near-threshold) concentrations of collagen at which concentration only platelet shape change was induced without aggregation. The platelet aggregation was also induced by some other catecholamines and clonidine but not by beta-agonist isoproterenol. The aggregatory potencies of R-(-)-isomers, (-)-epinephrine and (-)-norepinephrine were higher than the corresponding desoxy derivatives, epinine and dopamine. In addition, the epinephrine-induced rat platelet aggregation was inhibited by alpha2-antagonists, yohimbine and phentolamine, but not by alpha1-antagonist prazosin or beta-antagonist propranolol. These results suggested that the epinephrine-induced rat platelet aggregation is occurring through alpha2-adrenergic receptors as is the case with human platelets.
authors.affiliation: Natural Products Research Institute, Seoul National University, 110-460, Seoul, Republic of Korea. hsyun@snu.ac.kr
authors.forename: H S
authors.initials: HS
authors.lastname: Yun-Choi
authors.forename: K M
authors.initials: KM
authors.lastname: Park
authors.forename: M K
authors.initials: MK
authors.lastname: Pyo
mesh_terms: D018674:Adrenergic Antagonists / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects*; D002395:Catecholamines / Q000494:pharmacology; D048429:Cell Size / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D009391:Nephelometry and Turbidimetry; D010949:Plasma / Q000166:cytology / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D051381:Rats
chemical_list: D018674:Adrenergic Antagonists; D000316:Adrenergic alpha-Agonists; D002395:Catecholamines; D003094:Collagen; D004837:Epinephrine