Dose-response study of asthmatic volunteers exposed to XXXX during intermittent exercise.

@entity565 @entity7459 @entity6836 @entity1576
Twenty-one mildly asthmatic volunteers were exposed to 0, 0.3, 1.0, and 3.0 ppm @entity7459 ( @entity6836 ) in purified background air in an environmental control chamber. Exposures were separated by 1-wk periods and occurred in random order. Each lasted 1 hr and included three 10-min bouts of moderately heavy exercise (mean ventilation rate 41 L/min). Exposure temperature was near 22 degrees C and relative humidity near 50%. Specific airway resistance and maximal forced expiratory performance were measured preexposure, after the initial exercise, and near the end of exposure. Bronchial reactivity was assessed immediately following exposure, by normocapnic hyperventilation with subfreezing air. Symptoms were recorded on questionnaires before, during, and for 1-wk after each exposure. Exercise induced significant bronchoconstriction regardless of @entity6836 level. No statistically significant untoward response to @entity6836 was observed at any exposure concentration. This negative finding agrees with our previous results, but contrasts with findings elsewhere of @entity1576 after exposure to 0.3 ppm. The discrepancy is presently unexplained, but it may relate to different severity of @entity565 in different subject groups.
