NCIt definition : The hydrochloride salt form of protokylol, a derivative of the beta-adrenergic receptor
agonist isoproterenol with bronchodilator activity. Protokylol binds to beta-2 adrenergic
receptors in bronchial smooth muscle, thereby activating intracellular adenyl cyclase,
an enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3',5'-adenosine
monophosphate (cAMP). Increased cAMP levels cause relaxation of bronchial smooth muscle,
relieve bronchospasms, improve mucociliary clearance and inhibit the release of mediators
of immediate hypersensitivity from cells, especially from mast cells.;