title: Tyramine neurotoxicity and first-pass brain technetium-99m-diethylenetriamine penta-acetic acid.
abstract: Tyramine induces coma in phenelzine-treated dogs with liver disease. The objective of the present investigation was to examine the influence of tyramine in these monoamine oxidase-inhibited dogs on the kinetics of Tc-99m-diethylenetriamine penta-acetic acid (Tc-99m-DTPA) during its first passage through the brain by nuclear imaging techniques. The study began with anesthetized mongrel dogs (n = 10) in a supine position over the camera detector. Data acquisition was started simultaneously after the rapid intracarotid injection of Tc-99m-DTPA (5 mCi) and 60 0.5-sec images of the brain were taken. Tyramine induced increased uptake with a concomitant impairment in the elimination of Tc-99m-DTPA from the brain of these phenelzine-treated animals with hepatic injury (n = 5) as compared to pretreated animals serving as a control group or phenelzine-treated animals without liver disease. This was accompanied by an appreciable reduction in hemispheric cerebral blood flow (50.5 +/- 19.3 vs. 110 +/- 16 ml/100 g/min), respectively. Increased cerebrovascular permeability of Tc-99m-DTPA and decreased cerebral blood flow occurred concomitantly with increased cerebrospinal fluid pressure and elevation in cerebrospinal fluid catecholamines of monoamine oxidase-inhibited animals with hepatic injury.
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D056486:Chemical and Drug Induced Liver Injury; D004285:Dogs; D004298:Dopamine / Q000097:blood / Q000134:cerebrospinal fluid; D004347:Drug Interactions; D004837:Epinephrine / Q000097:blood / Q000134:cerebrospinal fluid; D006501:Hepatic Encephalopathy / Q000139:chemically induced; D007427:Intracranial Pressure / Q000187:drug effects; D007700:Kinetics; D008433:Mathematics; D008996:Monoamine Oxidase Inhibitors; D009638:Norepinephrine / Q000097:blood / Q000134:cerebrospinal fluid; D009942:Organometallic Compounds / Q000134:cerebrospinal fluid / Q000378:metabolism*; D004369:Pentetic Acid / Q000134:cerebrospinal fluid / Q000378:metabolism*; D010624:Phenelzine; D011877:Radionuclide Imaging; D013667:Technetium / Q000134:cerebrospinal fluid / Q000378:metabolism*; D016284:Technetium Tc 99m Pentetate; D014439:Tyramine / Q000633:toxicity*
chemical_list: D008996:Monoamine Oxidase Inhibitors; D009942:Organometallic Compounds; D013667:Technetium; D004369:Pentetic Acid; D010624:Phenelzine; D004298:Dopamine; D016284:Technetium Tc 99m Pentetate; D009638:Norepinephrine; D014439:Tyramine; D004837:Epinephrine