Ruthenium red protects HepG2 cells overexpressing CYP2E1 against acetaminophen cytotoxicity.

摘要

We studied the mechanisms of acetaminophen (APAP) cytotoxicity in HepG2 cells overexpressing cytochrome p4502E1, particularly the role of oxidativeitrosative stress and ryanodine Ca(2+) channel. Cells were grown for 24 h with APAP in the presence or absence of 4-methylpyrazole (4MP), L: -arginine methyl ester (L-NAME), superoxide dismutase (SOD), or ruthenium red (RuR). Drug cytotoxicity was also tested in cells pretreated overnight with V-PYRRO/NO. APAP was without effect on empty vector-transfected cells, but damaged CYP2E1-transfected cells and this was abolished by RuR, reduced by 4MP, or V-PYRRO/NO but affected by L-NAME or SOD. APAP increased microsomal [(3)H]-ryanodine binding, while microsomal Ca(2+) uptake was significantly lowered. RuR increased net microsomal Ca(2+) uptake and normalized cytosolic Ca(2+) levels. We can conclude that neither oxidative nor nitrosative stress is relevant to APAP cytotoxicity in cultured HepG2 cells, but our results point to ryanodine receptors as a potential crucial protein in the early stages of APAP cytotoxicity.