Basophils and exercise-induced hypoxemia in extreme athletes

This study examined whether the increase in histamine release (%H, i.e., pl asma histamine expressed as a percentage of whole blood histamine) associat ed with exercise-induced hypoxemia (EIH) is related to high training-induce d changes in basophil and osmolarity factors in arterial blood. All paramet ers were measured in 20 endurance athletes, 11 of whom presented an EIH (HT nor) and 9 of whom were nonhypoxemic (HThyp), and in 10 untrained control s ubjects (UT). Measurements were made at rest, at the maximal workload of an incremental exhaustive exercise test, and at the fifth minute of recovery. %H increased during exercise in HThyp (P < 0.01) but did not increase sign ificantly in HTnor and UT controls. The results indicated that 1) osmolarit y and Na+ and K+ concentrations did not differ between the two trained grou ps and 2) the basophil count and basophil histamine content did not differ among groups. We concluded that the %H increase associated with EIH was not due to a training effect on these parameters. The relatively low increase in histamine content during exercise in HThyp in comparison to HTnor (P < 0 .05) and UT (P < 0.01) and the low recovery vs. resting basophil count only in HThyp (P < 0.01) suggested an accentuated exercise-induced basophil deg ranulation in the hypoxemic athletes.