title: The effect of propranolol on catecholamine clearance.
abstract: Normal subjects given propranolol increased their plasma t1/2 for infused isoproterenol from 2.68 to 6.25 minutes. Propranolol increased plasma norepinephrine (NE) levels only slightly. Propranolol increased the t1/2 of isoproterenol but not that of NE in men with autonomic nervous system degeneration. This suggests that propranolol acts on nonneuronal uptake-2 processes, rather than on uptake-1 mechanisms. alpha-Blockers slow uptake-1 and beta-blockers slow uptake-2 processes. When 27 subjects exercised, those who attained the highest plasma levels of the alpha- and beta-receptor agonist NE also had the briefest apparent t1/2 for NE. Adrenergic receptor blocking drugs slow catecholamine clearance. NE may stimulate its own clearance.
mesh_terms: D001794:Blood Pressure / Q000187:drug effects; D004347:Drug Interactions; D006207:Half-Life; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D007545:Isoproterenol / Q000378:metabolism / Q000494:pharmacology*; D009638:Norepinephrine / Q000097:blood*; D005082:Physical Exertion; D011433:Propranolol / Q000494:pharmacology / Q000627:therapeutic use*; D011674:Pulse / Q000187:drug effects; D012791:Shy-Drager Syndrome / Q000188:drug therapy / Q000378:metabolism
chemical_list: D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine