Differences related to the production of arachidonic acid between collagen- and thrombin-stimulated human platelets.
The effects of collagen and thrombin on the liberation of free arachidonic acid were investigated in human platelets by fluorometric high-performance liquid chromatography. Collagen induced a concentration-dependent increase in the extent of platelet aggregation, as well as an accumulation of arachidonic acid in human platelets. By contrast, thrombin effectively provoked a potent aggregation at relatively low concentration without any accumulation of free arachidonic acid, although the accumulation of arachidonic acid was detected at a high concentration of thrombin (> 0.1 U/ml) that induced full aggregation. The selective liberation of arachidonic acid was found in thrombin-stimulated platelets. Non-selective liberation of fatty acids occurred in platelets that had been stimulated with a high concentration of collagen (10 micrograms/ml), as well as in platelets stimulated with A23187. The net amount of free arachidonic acid in collagen-stimulated platelets was estimated by use of eicosatetraenoic acid (ETYA), which is an inhibitor of both cyclooxygenase and lipoxygenase. ETYA markedly potentiated the accumulation of free arachidonic acid in collagen-stimulated platelets without changing the amounts of other fatty acids in the cell.
Fujita
M
M
Tokyo Research Institute, MECT Corporation, Saitama.
Nakagawa
Y
Y
Osawa
R
R
Kijima-Suda
I
I
Setaka
M
M
Nojima
S
S
Tomita
K
K
D016718:Arachidonic Acid / Q000096:biosynthesis* / Q000097:blood* / Q000502:physiology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003094:Collagen / Q000494:pharmacology*; D005227:Fatty Acids / Q000097:blood; D006801:Humans; D007700:Kinetics; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology; D013268:Stimulation, Chemical; D013917:Thrombin / Q000494:pharmacology*
D005227:Fatty Acids; D016718:Arachidonic Acid; D000001:Calcimycin; D003094:Collagen; D013917:Thrombin