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Effects of in vivo hepatic ischemia‐reperfusion injury on the CYP2E1‐mediated metabolism of chlorzoxazone and biliary clearance of its metabolite in isolated perfused rat livers
Author(s) -
Mehvar Reza,
Shaik Imam H.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.812.1
In our recent work, warm hepatic ischemia‐reperfusion (IR) injury reduced the in vivo clearance of the CYP2E1 marker chlorzoxazone (CZX) in rats. However, the AUC and renal excretion of the CZX metabolite, 6‐hydroxychlorzoxazone (HCZX), was unaffected. The purpose of the current study was to determine the reasons for this apparent discrepancy. Rats (n = 4–5/group) were subjected to sham operation (Sham) or 60 min of warm hepatic ischemia (70%), followed by 3 or 24 hr of in vivo reperfusion (IR). Livers were then isolated and perfused ex vivo using a CZX‐containing perfusate (~1 μg/mL) in a single‐pass manner for 60 min. The concentrations of CZX and HCZX in the inlet and outlet samples and bile were determined by HPLC. Moreover, kinetics of formation of HCZX, CYP2E1 protein, and cytochrome P450 reductase (CPR) activity were determined in liver microsomes. After 3 hr in vivo reperfusion, IR caused a significant (P < 0.05) decrease in the hepatic extraction ratio and clearance of CZX by ~30%. Additionally, it caused ~70% decrease in the biliary clearance and recovery of HCZX (P < 0.001), resulting in ~40% decrease (P < 0.01) in the total recovery of HCZX. Microsomal data showed ~50% decline in the intrinsic clearance of HCZX formation (P < 0.05). Whereas IR did not affect the CYP2E1 protein content (Western blot), the CPR activity was reduced (P < 0.05) by ~30% in the IR group. These IR‐induced changes returned to normal after 24 hr of in vivo reperfusion. We conclude that the similar AUCs of HCZX observed in the IR and Sham rats in vivo is most likely due to an IR‐induced lower biliary clearance of the metabolite.