– Isoproterenol-d7 is intended for use as an internal standard for the quantification of isoproterenol by GC- or LC-MS. Isoproterenol is an agonist of β1- and β2-adrenergic receptors (β1- and β2-ARs; Kis = 224 and 458 nM, respectively). It is selective for β1- and β2-ARs over β3-ARs (Ki = 1,570 nM). Isoproterenol inhibits contractions in isolated field-stimulated rat vas deferens (EC50 = 45.6 nM). In vivo, isoproterenol (0.33 mg/kg) decreases blood pressure and increases water intake in nephrectomized rats. It reduces blood pressure and increases heart rate in renal hypertensive rabbits. Isoproterenol inhibits histamine-induced bronchospasms in anesthetized dogs. Formulations containing isoproterenol have been used in the treatment of bradydysrhythmias and to improve breathing during anesthesia.