Alveolar epithelial integrity in athletes with exercise-induced hypoxemia

The effect of incremental exercise to exhaustion on the change in pulmonary clearance rate (k) of aerosolized Tc-99m-labeled diethylenetriaminepentaac etic acid (Tc-99m-DTPA) and the relationship between k and arterial Po-2 (P a-O2) during heavy work were investigated. Ten male cyclists (age = 25 +/- 2 yr, height = 180.9 +/- 4.0 cm, mass = 80.1 +/- 9.5 kg, maximal O-2, uptak e = 5.25 +/- 0.35 1/min, mean +/- SD) completed a pulmonary clearance test shortly (39 +/- 8 min) after a maximal O-2 uptake test. Resting pulmonary c learance was completed greater than or equal to 24 h before or after the ex ercise test. Arterial blood was sampled at rest and at 1-min intervals duri ng exercise. Minimum Pa-O2 values and maximum alveolar-arterial Po, differe nce ranged from 73 to 92 Torr and from 30 to 55 Torr, respectively. No sign ificant difference between resting k and postexercise k for the total lung (0.55 +/- 0.20 vs. 0.57 +/- 0.17 %/min, P > 0.05) was observed. Pearson pro duct-moment correlation indicated no significant linear relationship betwee n change in h for the total lung and minimum Pa-O2 (r = -0.26, P > 0.05). T hese results indicate that, averaged over subjects, pulmonary clearance of Tc-99m-DTPA after incremental maximal exercise to exhaustion in highly trai ned male cyclists is unchanged, although the sampling time may have elimina ted a transient effect. Lack of a linear relationship between h and minimum Pao, during exercise suggests that exercise-induced hypoxemia occurs despi te maintenance of alveolar epithelial integrity.