Adenosine and its role in asthma.

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