Effects of Intermittent Hypoxia on Platelet‐Eosinophil Aggregation Induced by Exercise under Shear Flow and Inflammation in Men

This study was to investigate the effect of intermittent hypoxia on heterotypic platelet‐eosinophil aggregation induced by exercise. Eleven healthy sedentary men exposed to normobaric hypoxia (i.e., 12% O 2 ) for 1 hour per day, 5 days per week for 4 to 8 weeks in a hypoxic chamber. At pre‐, 4‐week, and 8‐week hypoxia interventions, platelet‐eosinophil aggregation induced by shear stress, lipopolysaccharide (LPS), and N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP) were measures before and immediately after a progressive exercise test. Our results indicated that (1) 4 to 8 weeks of intermittent hypoxia enhanced aerobic capacity and elevated anaerobic threshold in these subjects; 2) prior to intervene hypoxia, strenuous exercise increased shear‐, LPS‐, or fMLP‐induced platelet‐eosinophil aggregation; (3) intermittent hypoxia for 4 weeks increased resting platelet‐eosinophil aggregation and augmented the extent of hetero‐aggregation induced by exercise under various shear flow and inflammatory conditions; and (4) intermittent hypoxia for 8 weeks reversed resting platelet‐eosinophil aggregation back to pre‐hypoxia treatment state and attenuated the extent of hereto‐aggregation induced by exercise. It is concluded that intervention of 4‐week hypoxia improves the subject's exercise performance, but simultaneously increases the risk of eosinophil‐related thrombosis evoked by vigorous exercise. However, 8 weeks of intermittent hypoxia maintains enhancement of physical fitness by hypoxia and also suppresses exercise‐induced hetero‐aggregation of platelet and eosinophil, thereby reducing the risk of thrombosis during exercise.