Response of Stored Platelets to Exogenous Arachidonic Acid

2015 ◽  
pp. 123-124
Author(s):  
Joseph C. Fratantoni ◽  
Betty J. Poindexter
Keyword(s):  
Arachidonic Acid ◽  
Exogenous Arachidonic Acid

THE REDUCED CAPACITY OF THROMBOXANE FORMATION IN THROMBIN-PREACTIVATED PLATELETS IS NOT CAUSED BY DEPLETION OF THEIR ARACHIDONIC ACID POOL

1987 ◽  
Author(s):  
R E Scharf ◽  
M Stockschläder ◽  
H J Reimers ◽  
W Schneider
Keyword(s):  
Arachidonic Acid ◽  
Human Platelets ◽  
Thrombin Receptor ◽  
Precursor Pool ◽  
Acid Pool ◽  
Exogenous Arachidonic Acid ◽  
High Concentrations ◽  
Short Time ◽  
Thromboxane Formation

Thromboxane (TX) synthesis of washed human platelets pretreated with high concentrations of thrombin (0.5-2.0 U/ml) for 20 sec is significantly reduced upon further thrombin stimulation. Compared to controls (tyrode-pretreated platelets), thrombin-preactivated platelets recover normal TX synthesis following exposure to exogenous arachidonic acid (AA) indicating that short-time thrombin treatment does not inactivate platelet cyclooxygenase or TX synthetase (Blood 63: 858, 1984). To evaluate whether the reduced TX synthesis upon -the second thrombin exposure is due to depletion of their AA precursor pool, thrombin-pretreated platelets and tyrode-pretreated platelets (5×108/ml) were resuspended in autologous ACD plasma and incubated at 37°C with 0.2 μCi 14C-AA (20 μM) for 60 to 90 min in the presence of PGE1 (10 μM). Mean platelet uptake of 14C-AA (disappearance of radioactivity from the supernatant) was 12+3 nmoles AA/109 platelets and did not differ significantly between thrombin-pretreated platelets and controls. Thrombin-pretreated platelets released 10% or 4.5% of their 14c-activity upon further exposure to thrombin (2 U/ml) or collagen (8 μg/ml), respectively. The release from control platelets (15% with thrombin, 6.5% with collagen) did not differ from that of thrombin-pretreated platelets. However, even after incubation in ACD plasma, thrombin-pretreated platelets continued to form significantly less TXB2 (5.0±1.6 nmoles/109 platelets) than controls (9.7±2.2 nmoles/109 platelets, p< 0.05). These data indicate that the reduced capacity of thrombin-pretreated platelets is due neither to a depletion of the endogenous AA pool nor to an inactivation of cyclooxygenase or TX synthetase. The reduced TX synthesis capacity may be caused by a modification, destruction or desensitization of the platelet thrombin receptor as a consequence of the preceding thrombin stimulation.

Paracoccidioides brasiliensis Uses Endogenous and Exogenous Arachidonic Acid for PGEx Production

2010 ◽  
Vol 170 (2) ◽  
pp. 123-130 ◽  
Author(s):  
Guilherme Augusto Biondo ◽  
Luciane Alarcão Dias-Melicio ◽  
Ana Paula Bordon-Graciani ◽  
Michele Janegitz Acorci-Valério ◽  
Angela Maria Victoriano Campos Soares
Keyword(s):  
Arachidonic Acid ◽  
Paracoccidioides Brasiliensis ◽  
Exogenous Arachidonic Acid
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