[13N]-beta-phenethylamine ([13N]PEA): a prototype tracer for measurement of MAO-B activity in heart.
[13N]beta-Phenethylamine ([13N]PEA) was evaluated as a radio tracer for the measurement of mouse heart monoamine oxidase (MAO) activity in vivo. After intravenous administration, [13N]PEA was deaminated by MAO-B. 13NH3 formed thereby was taken up by amino acids and trapped in the heart. The relation between the radioactivity trapped in the heart and the enzyme activity was examined. The radioactivity in the heart 15 min after administration was reduced in a dose-dependent manner by pretreatment with a specific MAO-B inhibitor, l-deprenyl, but not with a specific MAO-A inhibitor, clorgyline. A linear correlation existed between the heart radioactivity level and the heart MAO-B activity (0-45%). [13N]1,1-d2-2-Phenethylamine (C6H5-CH2-CD2-13NH2, [13N]d2PEA), a modified tracer with less reactivity towards the enzyme, was tested similarly. This tracer possessed a higher sensitivity than [13N]PEA, and a wider range (0-85%) of MAO-B activity correlated linearly with the trapped radioactivity. These results indicate that [13N]PEA derivatives ([13N]PEA and [13N]d2PEA) can be useful radiotracers for noninvasive measurements of MAO-B activity in the human heart.
D000641:Ammonia / Q000378:metabolism; D000818:Animals; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008995:Monoamine Oxidase / Q000032:analysis*; D009206:Myocardium / Q000201:enzymology*; D009590:Nitrogen Radioisotopes; D010627:Phenethylamines; D012642:Selegiline / Q000494:pharmacology
D009590:Nitrogen Radioisotopes; D010627:Phenethylamines; D012642:Selegiline; C029261:phenethylamine; D000641:Ammonia; D008995:Monoamine Oxidase