Fig. 5.

Evidence of increased platelet reactivity at 5,200 m. Platelet function was assessed on Apex 4 using Multiplate electrode aggregometry assays on whole blood activated by ( A ) thrombin receptor activating peptide (TRAP), ( B ) Collagen (COL) or (C) adenosine diphosphate (ADP). Area under the curve (AUC) represents the degree of platelet aggregation over time. ( D ) Platelet function was assessed on Apex 2 using a PFA-100 device and collagen-epinephrine cartridges. Increased platelet reactivity reduces closure time. Data are mean (horizontal bars) ± SEM. ** p  < 0.01, ***** p  < 0.00001 using paired t -tests corrected for multiple comparisons using the Bonferroni method, ( C ) p  < 0.016 or ( D ) p  < 0.0083 accepted as significant. Apex 2 data points are represented by closed circles; Apex 4 data points are represented by open circles.