Urinary cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) in asthmatic and normal children.

Urinary excretion of cAMP and cGMP was studied in nine normal and 15 asthmatic children. Bronchial lability was studied with a treadmill running test and atopy with serum IgE and skin prick tests. A circadian rhythm was found in both groups for cAMP and cGMP excretion. Cyclic GMP levels were higher in the asthma group, the difference reaching statistical significance around the time of the exercise challenge test. The fall in PEF induced by exercise showed a significant negative correlation with urinary cAMP responsiveness to isoproterenol inhalation. Exercise-induced bronchial lability correlated with 24-h cGMP excretion. High cGMP and low cAMP levels at night could be connected with nighttime exacerbations of symptoms. It is suggested that cGMP might have a more important role in asthma, than previously assumed.