Nitric oxide and peroxynitrite regulate transporter transcription in rat liver slices.

To determine the role of nitric oxide (NO) in rat liver transporter regulation, we investigated in precision-cut liver slices the effect of NO and peroxynitrite (ONOO(-)), a reaction product of NO with superoxide (O(2(-))), on mRNA levels of 13 influx and efflux transporters. To inactivate Kupffer cells (KCs), liver slices were prepared from rats treated with gadolinium chloride (Gd). Transporter mRNA levels were determined after incubation of untreated (normal-slices) and Gd-pretreated slices (Gd-slices) for 18 h with Spermine NONOate (SpNO), an NO donor, and SIN-1 (3-(4-morpholinyl) sydnonimine hydrochloride, SIN), a ONOO(-) donor.

Effect of aminoguanidine on lipopolysaccharide-induced changes in rat liver transporters and transcription factors.

To determine the role of nitric oxide (NO) in rat liver transporter regulation, we investigated whether NO mediates lipopolysaccharide (LPS)-induced changes in transporters and their transcription factor expression using aminoguanidine (AG), an inhibitor of induced nitric oxide synthase (iNOS). We confirmed that LPS decreased mRNA levels for Ntcp, Oatp1, Oatp2, Oatp4, Oct1, Mrp2, Mdr1a and increased those for Mdr1b at 16 h after administration. AG attenuated these decreases for Ntcp, Oatp1 and Oatp4 (retinoid X receptor (RXR)alpha- and hepatocyte nuclear factor (HNF)4alpha-dependent genes) and increase for Mdr1b (nuclear factor (NF)-kappaB-dependent gene).