The role of sulphide and sulphide oxidation in the copper molybdenum antagonism in rats and guinea pigs.

The sulphide metabolism of rats fed molybdate up to levels of 1000 ppm molybdenum was examined and large decreases in hepatic sulphite oxidase activity observed; overall sulphide oxidation capacity was also reduced. Molybdate but not tungstate caused increases in the total plasma copper of guinea pigs but in particular the appearance of a new TCA-insoluble fraction. The effect was increased by the addition of 500 ppm sulphur as sulphide, to the molybdate diet whereas the addition of 500 ppm S as sulphate was ineffective. 100 ppm Mo was less effective as thiomolybdate (MoS4=) than as molybdate. The significance of these results in relation to the role of sulphide in the Cu-Mo-S interaction is discussed.