Washed platelets

BAY 41-2272 is a novel non-NO-based soluble GC activator. It produced a marked inhibition of platelet aggregation in washed platelets and PRP, however, with much lower potency in PRP. Both NO and prostacyclin exhibited synergistic activity with BAY 41-2272 to inhibit platelet aggregation. In vivo, BAY 41-2272 significantly reduced blood pressure in rats, but it had only a small effect on FeCl3-induced thrombosis [107]. 

Platelet Aggregation and Deaggregation in Platelet-Rich Plasma or Washed Platelets (Born Method)... 

The entire procedure is performed in plastic (polystyrene) tubes and carried out at room temperature. Freshly collected venous blood is anticoagulated with hirudin (1 volume + 9 volumes of animal blood) or ACD solution (1 volume + 9 volumes of human blood) and centrifuged at 170 x g for 15 min to obtain platelet-rich plasma (PRP). The PRP-supematant is carefully removed, and the rest is further centrifuged at 1500 x g for 10 min to obtain platelet-poor plasma (PPP). PRP is diluted with PPP to a platelet count of 3 x 108/ml before use in the aggregation assays. To obtain washed platelets (WP), 8.5 volumes of human blood are collected into 1.5 volumes of ACD and centrifuged as for PRP. PRP is acidified to a pH of 6.5... 

This technique can not be applied in whole blood yet but can be used with PRP, washed platelet or GFP. 

Kirk, R.I., Deitch, J.A., Wu, J.M., and Lerea, K.M., Resveratrol decreases early signalhng events in washed platelets but has httle effect on platelet aggregation in whole blood. Blood Cells Mol. Dis., 26, 144, 2000. 

Thrombosthenin is extracted from a concentrated suspension of washed blood platelets obtained by any of the described methods of isolation (Maupin, 1954b). Bettex-Galland and Liischer (1961), starting with 50 liters of freshly (collected citrated human blood isolated by differential centrifugation in the (told, from the buffy layers, 20 to 30 ml of a highly concentrated suspension of washed platelets. Since the isolation of thrombosthenin is based on its solubility properties, special ce,re must be taken to eliminate the leucocytes their content of deoxyribonuclcoproteids... 

Figure 7. Adenosine effect on vasopressin-induced intracellular Ca mobilization in washed platelet suspension. (Reproduced from publication of Agatwal, et al., Ref. 74)...

However, increased platelet aggregation response in SHR has not been found to be universal. In our laboratory, under identical experimental conditions utilizing the same washed platelet samples at the same time, we have observed that while fiuombin induces a greater platelet aggregation response in SHR, ADP induces a lesser fibrinogen binding... 

PPADS was investigated fiirther for its ability to inhibit ADP-induced platelet aggregation [32]. As shown in Figure 5, PPADS (100 and 500 pM) was able to inhibit P2 p-purinoceptor-mediated responses in human washed platelets. However, comparing the effective threshold concentration of PPADS in platelets (100 pM Figure 5) with that found for the P2X Subtype (1.0 pM Figure 3), it becomes obvious that PPADS is highly selective for P2X" P2T P o P o S-... 

We observed recently that a relatively high concentration (300 pM) of phthalide 20 in rat PRP significantly inhibited platelet aggregation induced by collagen but not by ADP and U-46619 (a thromboxane A2 receptor agonist) [299]. The inconsistency between the previously reported data and our results may be due to the different species (rat versus rabbit) and preparations (platelet-rich plasma versus washed platelets) used. 

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