Moderate intensity exercise mediates comparable increases in exhaled chloride as albuterol in individuals with cystic fibrosis

Rationale Despite the demonstrated advantageous systemic changes in response to regular exercise for individuals with cystic fibrosis (CF), exercise is still viewed as an elective rather than a vital component of therapy, and it is likely that these benefits extend to and are partially mediated by exercise-induced changes in ion regulation. Objective We sought to determine if exercise could provide comparable improvements in ion regulation in the CF lung as albuterol, measured using exhaled breath condensate (EBC) collection and nasal potential difference (NPD). Methods Fourteen CF (13-42 yrs.) and sixteen healthy (18-42 yrs.) subjects completed a randomized crossover study of albuterol and submaximal exercise. EBC was collected at baseline, 30- and 60-min post-albuterol administration, and at baseline and during three separate 15 min cycling exercise bouts at low, moderate, and vigorous intensity (25, 50 and 65% of the maximum workload, respectively). NPD was performed at 30- and 80-min post albuterol or following moderate and vigorous intensity exercise. Results CF subjects had lower EBC Cl^-, but no difference in EBC Na⁺ at baseline when compared to healthy subjects. EBC Cl^- increased four-fold with moderate exercise which was similar to that seen 60-min post albuterol administration for CF subjects. Neither exercise nor albuterol altered EBC Na⁺. The change in NPD voltage with amiloride (ΔAmil) was greater and there was minimal Cl^- secretion (ΔTCC) seen at baseline in the CF compared to the healthy subjects. ΔAmil was greater with both albuterol and exercise when compared to baseline within both CF and healthy groups, but there was no significant difference in the ΔTCC response with either treatment. Conclusion Both exercise and albuterol can alter ion regulation increasing Cl^- secretion to a significant and similar degree in individuals with CF.