Nedocromil sodium and diphenhydramine HCl ameliorate exercise-induced arterial hypoxemia in highly trained athletes

Introduction: Exercise-induced arterial hypoxemia (EIAH) has been observed in highly trained endurance athletes during near maximal exercise, which may be influenced by a histamine-mediated inflammatory response at the pulmonary capillary-alveolar membrane. In order to test this hypothesis, we examined whether the mast cell stabilizer nedocromil sodium (NS) and H-1-receptor antagonist diphenhydramine HCL (DH) would ameliorate EIAH and mitigate the drop in arterial oxyhemoglobin saturation (SaO2) during intensive exercise. Methods: Seven highly trained male cross country runners (age, 21 +/- 2 years; (V) over dotO(2max), 74.7 +/- 3.5 ml.kg(-1).min(-1)) participated in the study. All subjects completed a maximal exercise treadmill test to exhaustion, followed by three 5-min constant-load exercise bouts at 70%, 80%, and 90% (V) over dotO(2max). Prior to testing, subjects received either placebo (PL), NS, or DH. Results: Compared to PL, there was a significant treatment effect on SaO2 (p < 0.001) for both NS and DH during both constant-load exercise and at (V) over dotO(2max). Post hoc tests revealed SaO2 values, compared to PL, were significantly higher at (V) over dotO(2max) and during DH trials and higher with NS at constant-load intensities except at 70% (p = 0.13). Conclusion: The findings provide further evidence that histamine contributes directly or indirectly to the development of EIAH during intense exercise in highly trained athletes.

Automated summary

This study found that histamine plays a role in the development of exercise-induced arterial hypoxemia (EIAH) during intense exercise in highly trained athletes. The use of the mast cell stabilizer nedocromil sodium (NS) and H-1-receptor antagonist diphenhydramine HCL (DH) can improve EIAH and increase arterial oxyhemoglobin saturation (SaO2).