Inhibition of sulfur dioxide on cytochrome P4501 A in rats

  Objective   To study the effects of sulfur dioxide(SO₂)on hepatic and pulmonary cytochrome P4501A1 (CYP1A1)and 1A2(CYP1A2)in rats.

  Methods   Male Wistar rats were housed in exposure chambers and treated with different concentrations of SO₂.Fluorescence spectrophotometry was used to study the activities of CYP1A1 and 1A2.The mRNA levels of CYP1A1 and 1A2 were analyzed in livers and lungs by using a real-time reverse transcription-polymerase chain reaction(real-time RT2PCR)assay.

  Results   The mRNA levels of CYP1A1 and 1A2 in lungs and livers, the activities of CYP1A1 in livers and those of CYP1A1 and CYP1A2 in lungs were significantly decreased in rats exposed to SO₂ at 14 and 28 mg/m³.Furthermore, the decreases of activities and mRNA levels of these P450 enzymes caused by SO₂ at different concentrations in lungs and livers of rats followed linear dose-response curves.The hepatic CYP1A2 activities were decrased in rats exposed to SO₂ at 56 mg/m³.

  Conclusion   SO₂ exposure can suppress the activities and mRNA levels of CYP1A1 and 1A2 in the lungs and livers of rats.The capacity of the liver and the lung to metabolize drugs and xenobiotics can be compromised in both animals and humans.