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|Type:||Artigo de periódico|
|Title:||Platelet adhesion and intracellular calcium levels in antigen-challenged rats|
de Mello, GC
|Abstract:||There is considerable evidence that platelet activation occurs in allergic airways diseases. In this study we aimed to investigate platelet adhesion to immobilized fibrinogen and intracellular calcium levels in a rat model of allergic inflammation. Male Wistar rats were challenged with ovalbumin (OVA). At 30 min to 24 h after OVA-challenge, assays of platelet adhesion to immobilized fibrinogen and intracellular calcium levels using fura 2-AM loaded platelets were performed. The serum levels of IgE were approximately 5-fold greater in OVA-sensitized rats. A marked eosinophil influx in bronchoalveolar lavage (BAL) fluid of OVA-challenged rats at 24 h after OVA-challenge was also seen. OVA-challenge resulted in a marked thrombocytopenia, as observed within 12 h after OVA-challenge. The agonists ADP (0.5-50 mu M) and thrombin (30-100 mU/ml) concentration-dependently increased platelet adhesion to immobilized fibrinogen. At an early time after OVA-challenge (30 min), platelets exhibited greater platelet adhesion compared with the non-sensitized group, whereas at a late time (24 h) they exhibited lower platelet adhesion to both agonists. Moreover, at 30 min after OVA-challenge, intracellular calcium levels to ADP (20 mu M) and thrombin (100 mU/ml)-activated platelets were greater compared with non-challenged rats. As opposed, at 24 h after OVA challenge, a lower intracellular calcium level to ADP- and thrombin-activated platelets was observed. In conclusion, OVA-challenge in rats promotes a biphasic response in platelet adhesion consisting of an increased adhesion and intracellular calcium levels at an early phase (30 min), which progress to a reduction in adhesion and intracellular calcium levels at a late time (24 h) after antigen challenge. (C) 2010 Elsevier Ltd. All rights reserved.|
|Editor:||Academic Press Ltd- Elsevier Science Ltd|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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