plasma serotonin , dopamine , norepinephrine , and epinephrine were determined by radioenzymatic assays in blood samples withdrawn at frequent intervals for 2 h , simultaneously from the indwelling catheter and from a catheter temporarily inserted into a saphenous vein other than the one used for the injection of tryptophan .
C0028351
norepinephrine
C0014563
epinephrine