An Enzymatic Radioassay ofDopamine-β-hydroxylase in Serum and Tissues

Abstract

Details of an enzymatic radioassay procedure ofdopamine-β-hydroxylase in serum and tissues have been described. The method is based on the formation of octopamine from tyramine by dopamine-β-hydroxylase and a subsequent conversion of octopamine to N-¹⁴C-methyl-octopamine by the second incubation with S-adenosyl-L-methionine-(methyl-¹⁴C) and phenylethanolamine-N-methyltransferase. The normal value of human serum and examples of the activities of human sera in various diseases, as well as the activities in rat sera have been shown.