5-Hydroxytryptamine (5-HT)-induced shape change in human platelets determined by computerized data acquisition: correlation with [125I]-iodoLSD binding at 5-HT2 receptors

• Published in: Blood coagulation & fibrinolysis Vol. 2; no. 1; p. 17
• Main Authors: Brazell, C, McClue, S J, Preston, G C, King, B, Stahl, S M
• Format: Journal Article
• Language: English
• Published: England 01-02-1991
• Subjects: Blood Platelets - drug effects; Blood Platelets - metabolism; Blood Platelets - ultrastructure; Humans; Lysergic Acid Diethylamide - analogs & derivatives; Lysergic Acid Diethylamide - metabolism; Receptors, Serotonin - drug effects; Receptors, Serotonin - metabolism; Serotonin - pharmacology; Serotonin Antagonists - pharmacology
• ISSN: 0957-5235
• DOI: 10.1097/00001721-199102000-00003

The 5-HT-induced shape change and subsequent aggregation of platelets provides a functional assay for 5-HT2 receptors. In the present study we describe a method to increase aggregometer sensitivity by digital conversion of the voltage produced by changes in light transmittance through a platelet suspension, thereby allowing accurate analyses of the primary shape-change response. The pharmacology of 5-HT-induced shape change was then compared with that of [125I]-iodoLSD binding in human platelets. 5-HT caused a dose-dependent change in platelet shape (maximum response 5 x 10(-6) M, EC50 10(-6) M). Furthermore, there was a significant correlation across a selection of drugs between IC50 values for inhibition of 5-HT-induced shape change and for inhibition of platelet binding of the 5-HT2 receptor ligand [125I]-iodoLSD. These results support the hypothesis that 5-HT-induced shape change and [125I]-iodoLSD binding in human platelets are mediated through the same receptor, and validate the methods of data acquisition described.