Sulfotransferases (SULTs) catalyze the sulfation of many endogenous compounds 
that include monoamine neurotransmitters, such as dopamine (DA), and thyroid 
hormones (iodothyronines). Decarboxylation of iodothyronines results in 
formation of thyronamines. In the mouse, thyronamines act rapidly in a 
nongenomic fashion to initiate hypothermia and decrease cardiac output and heart 
rate. These effects are attenuated after 1-4 h, and metabolism of thyronamines 
via sulfation may be a mechanism for termination of thyronamine action. We 
carried out this study to test thyronamine (T0AM), 3-iodothyronamine (T1AM), 
3,5-diiodothyronamine (T2AM), and 3,5,3'-triiodothyronamine (T3AM) as substrates 
for human liver and cDNA-expressed SULT activities. We characterized several 
biochemical properties of SULTs using the thyronamines that acted as substrates 
for SULT activities in a human liver high-speed supernatant pool (n=3). T1AM led 
to the highest SULT activity. Activities with T0AM and T3AM were 10-fold lower, 
and there was no detectable activity with T2AM. Thyronamines were then tested as 
substrates with eight cDNA-expressed SULTs (1A1, 1A2, 1A3, 1C2, 1E1, 2A1, 2B1a, 
and 2B1b). Expressed SULT1A3 had the greatest activity with T0AM, T1AM, and 
T3AM, whereas SULT1A1 showed similar activity only with T3AM. Expressed SULT1E1 
had low activity with each substrate. T1AM, the most active thyronamine 
pharmacologically, was associated with the greatest SULT activity of the 
thyronamines tested in the liver pool and in both the expressed SULT1A3 and 
SULT1E1 preparations. Our results support the conclusion that sulfation 
contributes to the metabolism of thyronamines in human liver and that SULT 
activities may regulate the physiological effects of endogenous thyronamines.