Exposure to hypoxia induces higher surface expression of platelet activation markers and increased clot retraction. (A-D) Washed platelets from hypoxia-exposed and control animals were either stimulated with ADP (activated) or left unstimulated (resting). The αIIbβ3 and CD41 surface expressions were determined by flow cytometric analysis, using fluorescein isothiocyanate-conjugated antibodies. Flow cytometry histograms from representative experiments (A-B) and quantitation of fluorescence expressed as mean fluorescence intensities (C-D) are shown. Data are presented as mean ± SEM, a typical result of at least 3 independent experiments (n ≥ 6; *P < .05 vs activated control). (E-F) Clot retraction assay was performed in platelet rich plasma (PRP) isolated from control and exposed animals, as described in the supplemental Methods. The clot retraction in exposed animals was found to be significantly greater than in control animals. Shown are representative images of the clot retraction assay for different incubation periods; the clot size was quantified using ImageJ software and expressed as percent retraction of clot (mean ± SEM; n = 6). *P < .05, **P < .01 vs control. See the supplemental Methods for details.
