VITAMIN-E DOES NOT PREVENT EXERCISE-INDUCED INCREASE IN PULMONARY CLEARANCE

It has been observed that sustained exercise results in a prolonged in crease in alveolar epithelial permeability, as assessed by the pulmona ry clearance rate of aerosolized Tc-99m-labeled diethylenetriaminepent aacetate (Lorino et al. J. Appl. Physiol. 67: 2055-2059, 1989). The in volvement of lipid peroxidation in this increased permeability was tes ted in seven nonsmoking volunteers by comparing the exercise-induced i ncreases in pulmonary Tc-99m-diethylenetriaminepentaacetate clearance before and after a 3-wk supplementation with oral vitamin E (1,000 IU/ day), according to a protocol designed as a single-blind crossover stu dy. The 60-min exercise was performed on a treadmill at a constant loa d corresponding to 80% of maximal O-2 uptake. Administration of vitami n E, a very important antioxidant, did not reduce the exercise-induced increase in lung clearance, suggesting that the exercise-induced incr ease in lung epithelial permeability does not primarily result from th e occurrence of lipid peroxidation in the alveolar membrane. This resu lt thus corroborates the hypothesis of an alteration of the intercellu lar tight junctions due to the mechanical effects of hyperventilation.