Effect of salbutamol inhalations of plasma and urinary cyclic adenosine monophosphate levels in asthmatics and non-atopic controls.

Twenty asthmatics and 14 non-atopic controls were given long-acting theophylline tablets, 400 mg twice daily, and were then challenged, after a control period, with 0.5 mg salbutamol as an inhalant, divided in two doses. Urinary and plasma cyclic adenosine monophosphate (cAMP) levels were determined at the beginning of the study, during theophylline treatment and after the challenge with salbutamol inhalation. In neither the asthmatics nor the controls did theophylline alone raise the concentration of cAMP in plasma or its excretion in urine. Inhalation of salbutamol caused a significant rise in plasma cAMP levels in the controls but not in asthmatics. The inhaled sympathomimetic aerosol caused a slight simultaneous rise in urinary cAMP excretion in non-atopic controls, but in the asthmatics. Our results show that sympathomimetics administered directly to the bronchial mucosa do not elicit the same metabolic cAMP response in asthmatics as in controls.