We have tested the hypothesis that the composition of alveolar surfactant varies with pattern of breathing and level of fitness. We examined three major components of surfactant, surfactant protein A (SP-A), disaturated phospholipids (DSP), and cholesterol (CHOL) in bronchoalveolar lavage (BAL) fluid from 12 healthy men before and after exercise. Fitness was assessed as work load/heart rate ([kpm · min-1]/[HR · HRmax-1]) achieved during cycling for 30 min at 90% theoretical maximal heart rate. Using a bronchoscope, four 20-ml vols of 0.15 M NaCl at 37° C were instilled and then recovered from first a right upper and then a right lower lobe segmental bronchus. As we found no differences in the BAL from upper and lower lobes, the fluid was combined. We found a direct relationship between CHOL and DSP (r(s) = 0.84, p < 0.001), SP-A and CHOL (r(s) = 0.40, p < 0.025), and between SP-A and DSP (r(s) = 0.44, p < 0.025). The change in the ratios CHOL/DSP, SP- A/CHOL, and SP-A/DSP immediately after exercise was correlated with fitness (r(s) = -0.56, p < 0.025; r(s) = 0.75, p < 0.005; r(s) = 0.62, p < 0.025, respectively). We conclude that the composition of surfactant can change rapidly with exercise in a manner related to fitness, and we suggest that this is consistent with the existence of at least two pools of tissue surfactant of different composition supplying the alveolar compartment.
|Number of pages||9|
|Journal||American journal of respiratory and critical care medicine|
|Publication status||Published - Jun 1994|