Demonstration of N-acetyldopamine in human kidney and urine. 
Free and conjugated dopamine and N-acetyldopamine concentrations were measured in human urine and kidneys by reversed phase high performance liquid chromatography with single-electrode electrochemical detection.  Conjugated N-acetyldopamine was found to occur in urine from six normal humans and in four out of six human kidneys.  Unconjugated N-acetyldopamine was detected in only one urine sample and in three of seven kidneys.  Urinary excretion of total N-acetyldopamine averaged 0.485 micromoles/day in the same subjects.  In the kidneys, total N-acetyldopamine concentration averaged 1.46 nanomoles/gram.  N-Acetyldopamine was not detected in human caudate nucleus, mouse whole brain, or liver from Rhesus monkey.  When daily urinary excretion rates of N-acetyldopamine were determined in six individuals by both single- and dual-electrode electrochemical detection, the results were highly correlated for both free and total N-acetyldopamine (r greater than 0.97, p less than 0.001).  Using dual-electrode electrochemical detection, conjugated N-acetyldopamine accounted for 96.4% of the total N-acetyldopamine excretion.  This value was 95.8% in the same individuals using single-electrode detection.