Inhaled adenosine and guanosine on airway resistance in normal and asthmatic subjects

Abstract

1 The airway response to the inhaled nucleosides, adenosine (6.7 × 10^-4-6.7 mg/ml) and guanosine (7.3 × 10^-4-1.4 mg/ml) was studied in normal and asthmatic subjects. Airway response, measured in the body plethysmograph, was expressed as percentage change in specific airway conductance (sGaw) from baseline.

2 Inhaled adenosine caused no change in sGaw in normal subjects but produced a dose-dependent reduction in sGaw in both allergic and non-allergic asthmatic subjects (76 and 62% reduction respectively at 6.7 mg/ml).

3 Kinetics of adenosine induced bronchoconstriction were studied in 12 asthmatic subjects who inhaled a single concentration of adenosine. Bronchoconstriction was maximal within 5 min (42% reduction in sGaw) with partial recovery by 30 min.

4 The related nucleoside guanosine caused no change in sGaw in normal or asthmatic subjects.

5 Adenosine, but not guanosine, is a potent bronchoconstrictor in asthma suggesting that it may have a specific pharmacological effect.