Bronchial constriction in smooth muscle tissue of the lung is a symptom of asthma and can be reversed by raising intracellular cAMP levels.
For each of the following molecules state whether they will increase or decrease cAMP levels and why. Which ones would be effective asthma therapeutics?
a) a b-adrenergic receptor agonist
b) a b-adrenergic receptor neutral antagonist
c) a b-adrenergic receptor inverse agonist
d) an inhibitor of adenylate cyclase activity
e) a non-hydrolyzable analog of GTP
Note that the b-adrenergic receptor is a GPCR that responds to adrenaline.