Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, PO BOX 6111, Campinas, São Paulo 13084-971, Brazil.
Pulm Pharmacol Ther. 2010 Aug;23(4):327-33. doi: 10.1016/j.pupt.2010.03.006. Epub 2010 Mar 20.
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 24h 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 24h after OVA-challenge was also seen. OVA-challenge resulted in a marked thrombocytopenia, as observed within 12h after OVA-challenge. The agonists ADP (0.5-50 microM) 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 (24h) they exhibited lower platelet adhesion to both agonists. Moreover, at 30 min after OVA-challenge, intracellular calcium levels to ADP (20 microM) and thrombin (100 mU/ml)-activated platelets were greater compared with non-challenged rats. As opposed, at 24h 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 (24h) after antigen challenge.
有相当多的证据表明血小板活化发生在过敏性气道疾病中。在这项研究中，我们旨在研究卵清蛋白（OVA）致敏大鼠模型中血小板对固定化纤维蛋白原的黏附和细胞内钙水平。雄性 Wistar 大鼠用 OVA 致敏。在 OVA 攻击后 30 分钟至 24 小时，使用负载 fura 2-AM 的血小板进行血小板对固定化纤维蛋白原的黏附和细胞内钙水平的测定。OVA 致敏大鼠的血清 IgE 水平约增加 5 倍。OVA 攻击后 24 小时，支气管肺泡灌洗液（BAL）中也可见明显的嗜酸性粒细胞浸润。OVA 攻击导致明显的血小板减少，这种情况在 OVA 攻击后 12 小时内即可观察到。激动剂 ADP（0.5-50μM）和凝血酶（30-100mU/ml）浓度依赖性地增加血小板对固定化纤维蛋白原的黏附。在 OVA 攻击后早期（30 分钟），与未致敏组相比，血小板表现出更大的血小板黏附，而在晚期（24 小时），它们对两种激动剂的血小板黏附较低。此外，在 OVA 攻击后 30 分钟，ADP（20μM）和凝血酶（100mU/ml）激活血小板的细胞内钙水平高于未受挑战的大鼠。相反，在 OVA 攻击后 24 小时，ADP 和凝血酶激活血小板的细胞内钙水平降低。总之，OVA 攻击在大鼠中促进了血小板黏附的双相反应，包括在早期（30 分钟）时增加黏附和细胞内钙水平，随后在抗原攻击后晚期（24 小时）时减少黏附和细胞内钙水平。
