The protective effects of thiol-containing compounds on mercuric chloride-induced acute inhibition of enzymes from mouse kidney.

The inhibitory effect of mercuric chloride on mouse kidney enzymes and the treatment of this inhibition with some thiol-containing compounds, e.g., dithiothreitol (DTT), dimercaptosuccinic acid (DMS) and D-penicillamine (Pen) was examined. To produce a significant inhibition of renal enzymes in vivo, it was necessary to administer 5 mg Hg/kg/day, s.c., once daily for 3 doses, and to sacrifice the animals 1 day after the last injection. With this Hg dose, microsomal Mg2+-Na+-K+-ATPase, mitochondrial Mg2+-HCO-3-ATPase and supernatant carbonic anhydrase activities decreased to about 30%, 70% and 60% of normal values, respectively. Combined administration of DTT (5-20 mg/kg, i.p.) and DMS (5-20 mg/kg, i.p.) with HgCl2 restored the enzyme activities to near normal or normal levels in parallel to the administered doses. The effect of Pen was slightly less than that of the above 2 compounds. This may be due to the number of thiol radicals, as Pen is a monothiol and the other 2 compounds are dithiol compounds. Since the toxicity of DMS is very low compared with DTT, DMS may be more suitable for the treatment of mercury poisoning.