Glucuronide and sulphate conjugation in isolated liver cells from control and phenobarbital- or PCB-treated rats

The conjugation of 4-methylumbelliferone, p-nitrophenol and o-aminophenol in isolated rat liver cells was studied. It was found that for maximum sulphate conjugation to take place a very high sulphate concentration (50 mM) was needed, indicating that the rate limiting step may be the formation of ‘active sulphate’. Under these conditions only a slight increase in the glucuronide/sulphate ratio with increasing substrate concentration was seen. Inducers of drug metabolism. PCB and phenobarbital, increased only glucuronidation. PCB was also found to cause qualitative changes in the metabolism of 4-methylumbelliferone.