Airway Tone During Exercise in Healthy Subjects: Effects of Salbutamol and Ipratropium Bromide

Abstract

In healthy subjects changes in airway calibre during exercise are conflicting and smaller than in asthmatics. Methodological differences could explain the discrepancies between the results obtained in healthy subjects. Therefore, our aim was to assess during exercise the changes in airway diameter and the effects of 200 µg salbutamol (SAL) or 40 µg ipratropium bromide (IPR) inhalations versus placebo (PLA), using spirometry and respiratory resistance (Rrs). Eight non-asthmatic subjects exercised 9 min at 70 % of their maximal aerobic power after inhalation of 200 µg SAL, 40 µg IPR, or PLA. Maximal flow-volume curves were obtained before and after inhalations, at 3 (E3) and 6 (E6) minutes of exercise, and during recovery. Rrs were measured by impulse oscillometry before and after inhalation, and immediately at the end of exercise. At rest, FEV₁ increased significantly after inhalation of SAL and IPR. Rrs decreased only after SAL. During exercise FEV₁ increased significantly from rest with SAL and IPR while forced mid expiratory flow (FEF_{25 - 75}) increased significantly for all conditions. At E6 the rise of FEV₁ and FEF_{25 - 75} were greater with SAL compared to PLA and IPR. In all conditions Rrs increased significantly immediately at the end of exercise as compared to rest but less than during flow-matched hyperpnea. It is concluded that a similar bronchodilation was observed during exercise with and without anticholinergic drug which suggests a withdrawal of parasympathetic control of airways during exercise in healthy subjects. Nevertheless, the bronchodilation observed during exercise is not maximal since it can be reinforced by β₂-mimetic drug.

Respiratory resistance - exercise - bronchodilation - healthy subject - parasympathetic tone

References

• 1 American Thoracic Society . Standardization and spirometry, update 1994.  Am J Resp Crit Care Med. 1995;  152 1107-1136
• 2 Beck K C. Control of airway function during and after exercise in asthmatics.  Med Sci Sports Exerc. 1999;  31 4-11
• 3 Beck K C, Hyatt R E, Mpougas P, Scanlon P D. Evaluation of pulmonary resistance and maximal expiratory flow measurements during exercise in humans.  J Appl Physiol. 1999;  86 1388-1395
• 4 Beck K C, Offord K P, Scanlon P D. Bronchoconstriction occurring during exercise in asthmatic subjects.  Am J Respir Crit Care Med. 1994;  149 352-357
• 5 Cochrane G M, Prieto F, Clark T J. Intrasubject variability of maximal expiratory flow volume curve.  Thorax. 1977;  32 171-176
• 6 de Bisschop C, Pichon A, Guénard H, Denjean A. Accounting for flow dependence of respiratory resistance during exercise.  Respir Physiol Neurobiol. 2003;  136 65-76
• 7 Fredberg J J, Inouye D, Miller B, Nathan M, Jafari S, Raboudi S H, Butler J P, Shore S A. Airway smooth muscle, tidal stretches, and dynamically determined contractile states.  Am J Respir Crit Care Med. 1997;  156 1752-1759
• 8 Freeman W, Javaid A, Cayton R M. The effect of ipratropium bromide on maximal exercise capacity in asthmatic and non-asthmatic men.  Respir Med. 1992;  86 151-155
• 9 Goubault C, Perault M C, Leleu E, Bouquet S, Legros P, Vandel B, Denjean A. Effects of inhaled salbutamol in exercising non-asthmatic athletes.  Thorax. 2001;  56 675-679
• 10 Jackson A C, Murphy M M, Rassulo J, Celli B R, Ingram Jr R H. Deep breath reversal and exponential return of methacholine-induced obstruction in asthmatic and nonasthmatic subjects.  J Appl Physiol. 2004;  96 137-142
• 11 Jennings S J, Warren J B, Pride N B. Airway caliber and the work of breathing in humans.  J Appl Physiol. 1987;  63 20-24
• 12 Johnson B D, Saupe K W, Dempsey J A. Mechanical constraints on exercise hyperpnea in endurance athletes.  J Appl Physiol. 1992;  73 874-886
• 13 Kagawa J, Kerr H D. Effects of brief graded exercise on specific airway conductance in normal subjects.  J Appl Physiol. 1970;  28 138-144
• 14 Krowka M J, Enright P L, Rodarte J R, Hyatt R E. Effect of effort on measurement of forced expiratory volume in one second.  Am Rev Respir Dis. 1987;  136 829-833
• 15 Lefcoe N M, Carter R P, Ahmad D. Postexercise bronchoconstriction in normal subjects and asthmatics.  Am Rev Respir Dis. 1971;  104 562-567
• 16 Mansfield L, McDonnell J, Morgan W, Souhrada J F. Airway response in asthmatic children during and after exercise.  Respiration. 1979;  38 135-143
• 17 McFadden Jr E R, Gilbert I A. Exercise-induced asthma.  N Engl J Med. 1994;  330 1362-1367
• 18 Skloot G, Togias A. Bronchodilation and bronchoprotection by deep inspiration and their relationship to bronchial hyperresponsiveness.  Clin Rev Allergy Immunol. 2003;  24 55-72
• 19 Stirling D R, Cotton D J, Graham B L, Hodgson W C, Cockcroft D W, Dosman J A. Characteristics of airway tone during exercise in patients with asthma.  J Appl Physiol. 1983;  54 934-942
• 20 Stubbing D G, Pengelly L D, Morse J LC, Jones N L. Pulmonary mechanics during exercise in normal males.  J Appl Physiol. 1980;  49 506-510
• 21 Todaro A. Exercise-induced bronchodilatation in asthmatic athletes.  J Sports Med Phys Fitness. 1996;  36 60-66
• 22 Warren J, Jennings S. Normal human airway response to exercise.  J Appl Physiol. 1984;  56 1686
• 23 Warren J B, Jennings S J, Clark T JH. Effect of adrenergic and vagal blockade on the normal human airway response to exercise.  Clin Sci (Colch). 1984;  66 79-85