The Inhibition by Chlorate of the Sulphation of Polyethyleneglycol in the Isolated Perfused Guinea Pig Liver

Abstract

1. The sulphation of polyethyleneglycol 200 by the isolated perfused guinea pig liver is inhibited to about 60% by 10 mM C1O⁻₃ in the plasma of the perfusate when the concentration of SO^2-₄ therein is 1.18 mM.

2. The inhibition is almost complete when the concentration of SO^2-₄ is about 0.1 mM, a level which can be achieved by using a modified Ringer-bicarbonate solution, devoid of sulphate, to prepare the perfusate.

3. Chlorate, presumably through its action on ATP-sulphurylase, may therefore be a useful inhibitor of sulphation in the isolated perfused liver when the activity of the sulphurylase is rate-limiting.

4. The rate of bile production in the presence of chlorate is no different from that in its absence showing that, in the time scale of the perfusion, chlorate is not a general liver poison.

5. When the synthesis of PAPS is not rate-limiting, as in the sulphation of oestrone metabolites by rat liver, chlorate has no effect on the rate of sulphation.