Assay of human erythrocyte catechol-o-methyltransferase activity with naturally occurring catecholamines as substrates.

This report describes a simple and sensitive radiometric assay for catechol-o-methyltransferase activity in human erythrocytes and other tissues. Saturating concentrations of the endogenous catecholamines and S-adenosylmethionine are used under optimum assay conditions. Erythrocyte catechol-o-methyltransferase activity is also dependent on storage conditions, as activity was lost at -20 degrees C but not at -80 degrees C.