Profiles of 67Cu in blood, bile, urine and faeces from 67Cu-primed lambs: effect of 99Mo-labelled tetrathiomolybdate on the metabolism of 67Cu after long-term storage.

1. The effectiveness of tetrathiomolybdate (TTM) in the removal of 67Cu from the long-term storage compartment in liver was studied. Lambs receiving 5 mg Cu/kg dry matter (DM) or 35 mg Cu/kg DM were primed intravenously (iv) with 67Cu and challenged 10 d later with 99Mo-labelled TTM given either iv or intraduodenally (id). The profiles of 67Cu and 99Mo and of Cu and of Mo with time were measured in blood, bile, urine and faeces. 2. The level of dietary Cu affected the amplitude of profiles of 67Cu and Cu in blood, bile and urine after administration of 99Mo-labelled TTM. TTM administration increased liver Cu removal and this was most marked in sheep given TTM iv. The liver Cu removal from the long-term storage Cu compartment was low and was not affected by the route of administration of TTM. Endogenous Cu excretion was higher in lambs given TTM id. 3. Excretion of 67Cu in bile through the transhepatocellular pathway after TTM administration appeared absent, while the transbiliary and hepatolysosomal pathways were operative. The potential reasons for this change are discussed. 4. TTM predominantly enhances the removal of Cu from the short-term storage compartment, but effects on the long-term storage compartment may still be of significance.