title: Stereospecific inhibition of 5-HT-induced increase of intracellular free calcium by (+)- and (-)-desmethoxyverapamil in human platelets.
abstract: The concentration of intracellular free calcium [Ca2+]i in human platelets was measured by the quin-2 method. 5-Hydroxytryptamine (5-HT) at 10(-5) M induced a rapid transient increase of [Ca2+]i which was antagonized by 10(-7) M ketanserin or cyproheptadine. The verapamil derivative, desmethoxyverapamil (D888), showed stereospecific inhibition of the 5-HT-induced [Ca2+]i increase. The IC50 for (-)-D888 was approx. 2 X 10(-8) M; (+)-D888 was almost 50 times less potent.
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D006801:Humans; D066298:In Vitro Techniques; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists; D013237:Stereoisomerism; D014700:Verapamil / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D012702:Serotonin Antagonists; D012701:Serotonin; C043184:4-desmethoxyverapamil; D014700:Verapamil; D002118:Calcium