In vivo effects of indomethacin on the activity of metal-containing enzymes

Interaction between indomethacin and heavy metal ions in aqueous solution

The interaction between indomethacin anions and heavy metal ions, such as cadmium, zinc and copper(II) ions, was studied in aqueous solution by polarographic techniques. Indomethacin anions form complexes with these heavy metal ions: the complex formed with cadmium ions is sparingly soluble, while more soluble and also stronger complexes are formed with zinc and copper(II). At high concentrations, where indomethacin anions undergo self-aggregation, these last compounds are solubilised. This property is briefly discussed and compared to that of bile salts. In the presence of calcium ions, indomethacin forms a poorly soluble salt and no evidence was detected for the formation of complex species.

Lipid peroxidation and antioxidant enzyme activity in aspirin-treated rats

1. Malondialdehyde formation and antioxidant enzyme activity after oral or intraperitoneal treatment of rats with various doses of aspirin was studied. 2. Aspirin, orally, had no effect on spontaneous, Fe(II)- or Fe(II)/ascorbate-induced malondialdehyde formation in liver homogenates; orally, ascorbate-induced malondialdehyde production was inhibited but only after 5-day treatment with 500 mg/kg aspirin; after intraperitoneal injection, the drug inhibited ascorbate- and Fe(II)/ascorbate-induced production of malondialdehyde. 3. Aspirin had no effect on malondialdehyde formation in erythrocytes, irrespective of the dose and route of drug administration. 4. Aspirin increased glutathione peroxidase activity in liver after 5-day treatment with an oral dose of 500 mg/kg and decreased enzyme activity in both liver and erythrocytes, 24 hr after a single injection of the same dose. 5. Aspirin, in vivo slightly affected lipid peroxidation and antioxidant enzyme activity.

In vitro effects of aspirin on malondialdehyde formation and on activity of antioxidant and some metal-containing enzymes

The in vitro effects of aspirin in different concentrations on malondialdehyde formation and on the activity of antioxidant and some metal-containing enzymes in rat liver homogenate and erythrocytes were studied. Aspirin showed a biphasic dependence on concentration: low concentrations (to 1.0 mM) stimulated the spontaneously formed malondialdehyde in the liver homogenate and the high concentration (5.0 mM) inhibited it; all aspirin concentrations tested had no effect on the liposomes; 5.0 mM aspirin inhibited the Fe(2+)-induced lipid peroxidation in the liver homogenate but had an opposite effect on the liposomes. Aspirin dose-dependently inhibited nitro-blue tetrazolium reduction and decreased deoxyribose degradation. The higher aspirin concentrations inhibited the activity of antioxidant and some metal-containing enzymes. It is suggested that these aspirin effects are determined by the aspirin-metal complexes formed rather than by aspirin itself.

Liver superoxide dismutases after copper deficiency and/or indomethacin treatment of rats

Copper deficiency in rats resulted in a decrease of liver cytosolic and lysosomal CuZnSOD activity (by 71% and by 55%, respectively) and in an increase of mitochondrial MnSOD (by 185%). The content of copper and zinc decreased by 64% and 38%, respectively, and that of manganese increased by 47%. Cytosolic CuZnSOD activity, both in control and copper-deficient rats, increased (by 71.5 units/mg protein and by 83.0 units/mg protein, respectively) after indomethacin treatment. Rat liver contained four CuZnSOD (cytosolic and lysosomal) and one MnSOD isoenzyme. Neither copper deficiency nor indomethacin treatment changed the position and the number of bands. The CuZnSOD-band with pI approximately 5.7 was greatly decreased by copper deficiency and was not restored to normal after indomethacin treatment.