Adenosine level in exhaled breath increases during exercise-induced bronchoconstriction

Abstract

In asthmatic patients, airway obstruction provoked by exercise challenge is accompanied by an increase in plasma adenosine level. In this study, the current authors investigated if exercise-induced bronchoconstriction was associated with local changes of adenosine concentration in the airways.Oral exhaled breath condensate (EBC) collection (5-min duration) and forced expiratory volume in one second (FEV1) measurements were performed at rest (baseline) and 4-8 times after treadmill exercise challenge in healthy and asthmatic subjects. Adenosine concentration in EBC was determined by HPLC.Observations indicated that physical exercise results in bronchoconstriction together with a significant increase of adenosine level in EBC in asthmatic patients (mean¡SD maximal fall in FEV1 27¡13%; associated increase in adenosine 110¡76% as compared to baseline), but not in healthy control subjects. Exercise-induced changes in adenosine concentration correlated significantly with the fall in FEV1 values in asthmatic patients.In conclusion, the observed increase in adenosine concentration of oral exhaled breath condensate most probably reflects changes in the airways during exercise-induced bronchoconstriction. Due to its known bronchoconstrictor property in asthma, adenosine may contribute to the development of bronchospasm.

Elevated Airway Purines in COPD

“…Adenosine, in particular, has been linked to infl ammatory airways diseases, 1 including twofold to fourfold elevations in blood 2,3 and BAL fl uid 4 of subjects with asthma. Similarly, adenosine concentrations in exhaled breath condensate (EBC) are elevated in subjects with stable asthma, 5,6 increased with asthma exacerbations, 7 and decreased with successful treatment. Findings from animal models, particularly the adenosine deaminase knockout mouse, 8,9 further support a link between airway infl ammation and lung adenosine.…”

Adenosine induces airway hyperresponsiveness through activation of A3 receptors on mast cells

“…In this report, we describe a previously unrecognized role for adenosine as an inducer of AHR. Because it is well established that adenosine levels are elevated in the asthmatic lung, 8,9 there is a strong implication that adenosine may contribute to the development of AHR in patients with asthma.…”

“…8,9 By activating 4 G-protein-coupled adenosine receptors (A 1 , A 2A , A 2B , and A 3 ) on immunocytes, neurons, goblet cells, and ASM, adenosine is believed to contribute to asthma pathogenesis. [8][9][10][11][12][13][14][15][16][17][18][19][20] However, a role for adenosine in the development of AHR has not been previously investigated. In smooth muscle cells, Gerwins and Fredholm 21 demonstrated that adenosine could stimulate Ca 2+ mobilization and enhance the contractile response to activation of G q/11 -coupled receptors.…”

Exhaled breath condensate: a comprehensive update

“…EBC adenosine has been shown to be significantly greater in patients with asthma, cystic fibrosis [ 162 ], allergic rhinitis during exercise [ 41 ] and in allergic rhinitis [ 163 ]. EBC is a useful method of measuring purinergic molecules compared with other sampling techniques, due to absence of confounding factors such as low EBC cellular and protein content [ 164 ].…”