Biomaterial Database

Thromboxane A2/prostaglandin H2 mobilizes calcium in human blood platelets. 1985

L D Brace, and D L Venton, and G C Le Breton

The present study investigated the mechanism by which thromboxane A2/prostaglandin H2 (TXA2/PGH2) stimulates platelet activation. Previous studies in isolated platelet vesicles have suggested that TXA2/PGH2 functions to release calcium from intraplatelet stores. On this basis, we investigated whether TXA2/PGH2 causes mobilization of calcium in intact platelets. Calcium redistribution was measured using the fluorescent probe, chlortetracycline (CTC), and a photon-counting microspectrofluorometer. Human platelet-rich plasma was incubated with CTC (50 microM) for 40 min at 25 degrees C. Shape change was induced with arachidonic acid (AA, 100 microM) or ADP (0.75-1.0 microM). It was found that AA addition resulted in a significant release of intraplatelet calcium. This release was blocked by inhibition of the cyclooxygenase with indomethacin (20 microM) or the specific TXA2/PGH2 antagonist, 13-azaprostanoic acid (13-APA, 100 microM). On the other hand, neither indomethacin nor 13-APA had any effect on calcium release stimulated by ADP. However, prostacyclin (13 nM) inhibited both AA- and ADP-induced calcium release. These findings provide evidence that cyclooxygenase products of AA, i.e., TXA2 and/or PGH2 directly caused the mobilization of intraplatelet calcium. Furthermore, this calcium mobilization appears to be mediated through a specific TXA2/PGH2 receptor interaction.

UI	MeSH Term	Description	Entries
D007213	Indomethacin	A non-steroidal anti-inflammatory agent (NSAID) that inhibits CYCLOOXYGENASE, which is necessary for the formation of PROSTAGLANDINS and other AUTACOIDS. It also inhibits the motility of POLYMORPHONUCLEAR LEUKOCYTES.	Amuno,Indocid,Indocin,Indomet 140,Indometacin,Indomethacin Hydrochloride,Metindol,Osmosin
D010974	Platelet Aggregation	The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.	Aggregation, Platelet
D011449	Prostaglandin Endoperoxides	Precursors in the biosynthesis of prostaglandins and thromboxanes from arachidonic acid. They are physiologically active compounds, having effect on vascular and airway smooth muscles, platelet aggregation, etc.	Endoperoxides, Prostaglandin
D011450	Prostaglandin Endoperoxides, Synthetic	Synthetic compounds that are analogs of the naturally occurring prostaglandin endoperoxides and that mimic their pharmacologic and physiologic activities. They are usually more stable than the naturally occurring compounds.	Prostaglandin Endoperoxide Analogs,Prostaglandin Endoperoxide Analogues,Synthetic Prostaglandin Endoperoxides,Analogues, Prostaglandin Endoperoxide,Endoperoxide Analogues, Prostaglandin,Endoperoxides, Synthetic Prostaglandin
D011463	Prostaglandins H	A group of physiologically active prostaglandin endoperoxides. They are precursors in the biosynthesis of prostaglandins and thromboxanes. The most frequently encountered member of this group is the prostaglandin H2.
D011464	Epoprostenol	A prostaglandin that is a powerful vasodilator and inhibits platelet aggregation. It is biosynthesized enzymatically from PROSTAGLANDIN ENDOPEROXIDES in human vascular tissue. The sodium salt has been also used to treat primary pulmonary hypertension (HYPERTENSION, PULMONARY).	Prostacyclin,Prostaglandin I2,Epoprostanol,Epoprostenol Sodium,Epoprostenol Sodium Salt, (5Z,9alpha,11alpha,13E,15S)-Isomer,Flolan,Prostaglandin I(2),Veletri
D011466	Prostanoic Acids	2-Octylcyclopentaneheptanoic acids. The family of saturated carbon-20 cyclic fatty acids that represent the parent compounds of the prostaglandins.	Acids, Prostanoic
D001792	Blood Platelets	Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.	Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002751	Chlortetracycline	A TETRACYCLINE with a 7-chloro substitution.	Aureocyclin,Aureomycin,Aureomycine,Biomycin,Chlorotetracycline,Chlortetracycline Bisulfate,Chlortetracycline Hydrochloride,Chlortetracycline Monohydrochloride,Chlortetracycline Sulfate (1:1),Chlortetracycline Sulfate (2:1),Chlortetracycline, 4-Epimer,Chlortetracycline, Calcium Salt,4-Epimer Chlortetracycline,Bisulfate, Chlortetracycline,Calcium Salt Chlortetracycline,Chlortetracycline, 4 Epimer,Hydrochloride, Chlortetracycline,Monohydrochloride, Chlortetracycline,Salt Chlortetracycline, Calcium