Factors influencing sulfation in isolated rat hepatocytes

Sulfation of harmol by isolated hepatocytes was dependent on an exogenous source of sulfate. Inorganic sulfate ion stimulated sulfation by over ten fold. Analysis of the stimulation of harmol sulfation by sulfate indicated a Km of 239 microM and a Vmax of 1.1 mumoles harmol sulfate/min/10(6) cells. Cysteine also stimulated the rate of harmol sulfation but was less effective than sulfate ion. Lithium chloride inhibited harmol sulfation. Sulfation was unaffected by several metabolic alterations which inhibited harmol glucuronidation. Fasting for 24 hours, and incubation with ethanol or linoleic acid, did not influence the rate of sulfation but inhibited glucuronidation by 50 percent.