Radioenzymic measurement of norepinephrine, epinephrine, and dopamine: stability, enzymic activity, and sensitivity.
We investigated factors affecting sensitivity and reproducibility of radioenzymic (catechol-O-methyltransferase) measurement of plasma catecholamines. There was no apparent deterioration of catecholamine during storage at -20 degrees C for 240 days. Accuracy and sensitivity of the assay depended mostly on the method of transferase preparation; its preparation by adjusting the pH to 6.8 before fractionation with ammonium sulfate resulted in an unsuitable enzyme with a relatively high background-radioactivity count, particularly for neorepinephrine and dopamine.
D002394:Catechol O-Methyltransferase; D004298:Dopamine / Q000097:blood*; D004355:Drug Stability; D004837:Epinephrine / Q000097:blood*; D006801:Humans; D008722:Methods; D009638:Norepinephrine / Q000097:blood*; D014316:Tritium
D014316:Tritium; D002394:Catechol O-Methyltransferase; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine