<prompt> Mechanism of action of Theophylline in Bronchial Asthma include all of the following, EXCEPT:Phosphodiesterase inhibitionAdenosine Receptor antagonismIncreased Histone DeacteylationBeta-2 Receptor stimulation  <response>: Theophylline has no action on beta 2 receptor. It is a methyxanthine, which cause bronchodilation mainly by increasing the cAMP levels, by inhibiting the phosphodiesterase enzyme. Mechanism of action of theophylline includes: 1 Release of calcium from the sarcoplasmic reticulum in skeletal and cardiac muscle. 2 Inhibition of phosphodiesterase 3 Blockage of adenosine receptor. Adenosine cause bronchoconstriction, dilate cerebral vessels and inhibit gastric secretion and cardiac pacemaker. Ref: Essentials of Medical Pharmacology By KD Tripathi, 5th Edition, Page 201 - 204. 