title: 5-hydroxytryptamine and platelet aggregation.
abstract: 5-Hydroxytryptamine (5-HT) activates blood platelets of various species including humans. In contrast to cat, pig, and sheep platelets, human blood platelets respond to 5-HT mainly with a shape change and a reversible aggregation only. However, depending on the concentration and the time interval between its addition and that of another agonist, 5-HT amplifies the human platelet aggregation induced by ADP, collagen, epinephrine, and norepinephrine; the monoamine itself induces strong aggregation of platelets presensitized with norepinephrine, lysolecithin, or Thrombofax. Prolonged exposure of platelets to 5-HT results in transient tachyphylaxis. Pharmacodissection and receptor-binding studies suggest the presence of functional receptors, possibly of the 5-HT2 (S2) type, different from the ones involved in the active uptake of the monoamine by the platelets. As a modulator of platelet reactions, 5-HT may be involved in secondary platelet aggregation, hemostasis, and thrombus formation.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*; D013045:Species Specificity
chemical_list: D011985:Receptors, Serotonin; D012701:Serotonin; D000244:Adenosine Diphosphate