Acute cholestasis-induced renal failure: Effects of antioxidants and ligands for the thromboxane A2 receptor

Acute cholestasis-induced renal failure: Effects of antioxidants and ligands for the thromboxane A2 receptor.BackgroundAcute biliary obstruction is associated with the development of renal impairment and oxidative stress. The F2-isoprostanes, formed during oxidant injury, are renal vasoconstrictors acting via thromboxane (TX)-like receptors. We determined whether the formation of F2-isoprostanes is increased in experimental cholestasis and whether thiol containing antioxidants or ligands for the TXA2 receptor could improve renal function.MethodsThe effects on renal function of acute bile duct ligation (BDL) in the rat were studied for two days. The consequences of administration of N-acetylcysteine (NAC), α-lipoic acid (LA), the TX receptor antagonist (TXRA) BAYu3405, or placebo were then examined.ResultsBDL caused a reduction in creatinine clearance from 1.10 ± 0.05 to 0.55 ± 0.05 ml/min and sodium excretion from 52 ± 3 to 17 ± 3 μmol/hr. Urinary F2-isoprostanes increased from 14 ± 2 to 197 ± 22 pg/ml following BDL. Renal functional changes were ameliorated by NAC (creatinine clearance 0.73 ± 0.05 ml/min), LA (0.64 ± 0.03 ml/min), and a TXRA (0.90 ± 0.15 ml/min); P < 0.05. Similarly, sodium excretion was increased from 17 ± 3 μmol/hr (placebo) to 34 ± 3 μmol/hr (NAC), 29 ± 3 μmol/hr (LA), and 38 ± 5 μmol/hr (TXRA); P < 0.005. Hepatic glutathione concentrations increased from 6.5 ± 0.3 μmol/g (normal liver) to 8.8 ± 0.5 μmol/g (NAC) and 7.7 ± 0.3 μmol/g (LA), P < 0.01. However, only LA markedly inhibited F2-isoprostane formation (197 ± 22 to 36 ± 11 pg/ml creatinine clearance; P < 0.05). Urinary TXB2 excretion was elevated after BDL (2.2 ± 0.5 to 111.1 ± 20.3 pg/min) but was unaffected by NAC and LA.ConclusionNAC, LA, and TXRA can partially prevent renal dysfunction in experimental cholestasis. The effects of the antioxidants are independent of their ability to inhibit lipid peroxidation or TX synthesis