title: Concurrent measurement of platelet ionized calcium concentration and aggregation: studies with the lumiaggregometer.
abstract: Platelet aggregation and aequorin-indicated cytoplasmic ionized calcium concentration ([Cai2+]) were measured simultaneously using a modification of a commercially available instrument, the Chronolog Whole Blood Lumiaggregometer. The [Cai2+] rise in response to arachidonic acid, the Ca2+-ionophore A23187, collagen, and epinephrine occurred either before or simultaneously with platelet shape change or aggregation. PGD2 caused concentration-dependent inhibition of both the [Cai2+] rise and aggregation. However, suppression of the [Cai2+] rise alone did not fully account for the inhibition of aggregation due to the elevated cAMP produced by PGD2. Agonist-induced elevation of [Cai2+] did not depend on platelet aggregation, but was enhanced by close platelet-to-platelet contact. Concurrent measurement of platelet aggregation and [Cai2+] may further clarify pathways to platelet activation.
mesh_terms: D000331:Aequorin; D000634:Aminoquinolines; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001792:Blood Platelets / Q000032:analysis*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood*; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005456:Fluorescent Dyes; D006403:Hematologic Tests / Q000379:methods; D006801:Humans; D008163:Luminescent Measurements; D010974:Platelet Aggregation / Q000187:drug effects; D015230:Prostaglandin D2; D011457:Prostaglandins D / Q000494:pharmacology
chemical_list: D000634:Aminoquinolines; D001095:Arachidonic Acids; D005456:Fluorescent Dyes; D011457:Prostaglandins D; D016718:Arachidonic Acid; D000001:Calcimycin; D000331:Aequorin; D003094:Collagen; C035739:Quin2; D015230:Prostaglandin D2; D002118:Calcium; D004837:Epinephrine