Adenosine and its role in asthma

Endogenous adenosine formed from ADP and AMP by the action of ATPase am 5'- nucleotidase is known to cause bronchoconstriction and asthma in humans. It ha: been suggested that this action of adenosine is due to its binding to specific purine receptors in the mast cells in the lungs and consequent release of mediators whicl elicit bronchoconstriction and asthma. The release of these mediators leading to asthm was also believed to be due to vagal stimulation by adenosine. Though the role a adenosine in causing bronchoconstriction leading to asthma is well confirmed the actus mode of action and details of the mechanisms involved in the clinical manifestation o asthma remain unclear.