 The investigators preliminary work provides primary evidence that activated platelets play a novel role in the initiation of tissue injurious and inflammatory responses at the microvascular interface. As such, platelets aggregate in close proximity to perivascular mast cells, a cell type that can rapidly launch powerful inflammatory responses through release of preformed effectors. Platelet activation alone is sufficient to stimulate these mast cells in vitro while, conversely, pharmacological inhibition of platelets reduce mast cell-dependent inflammation and end organ injury after rat circulatory arrest. 