Effect of exogenous heme on sulfide-induced changes in rat heme metabolism

Intraperitoneal heme treatment (5 mg/kg body wt) reversed the effects of a preceding (2 h) intraperitoneally injected Na2 S (150 mumol/kg body wt) dose on blood delta-amino levulinic acid synthase and heme synthase activities. The sulfide dosing caused decreased activity of both enzymes of which that of heme synthase was overcorrected above controls by the heme treatment 25 h after the sulfide dose. Heme alone caused a transient induction in the heme oxygenase activity in liver 23 h after the injection. The effects on heme synthesis in the sulphide-dosed rats support the role of the inactivation of the heme-controlled translational inhibitor of protein synthesis by the supply of exogenous heme.