The role of the fenestrated liver sinusoidal endothelial cells (LSECs) in the hepatic disposition of paracetamol was investigated in isolated perfused livers from rats treated with poloxamer 407 (P407), a surfactant that causes extensive defenestration of the LSECs. Bolus doses containing tracer amounts of (14)C-paracetamol and reference markers (Evans Blue, (3)H-sucrose) were injected into control rats and rats that had been administered P407 via intra-peritoneal injection 24 h prior to experimentation. Scanning electron microscopy confirmed a reduced number of fenestrations in rats treated with P407. The recovery of paracetamol was significantly increased in P407 rats compared to controls (0.72 ± 0.07 P407 vs. 0.67 ± 0.04 control, p < 0.05) and the volume of distribution of paracetamol as a fraction of the sucrose volume was significantly reduced. The permeability-surface area (PS) product for the transfer of paracetamol across the LSECs was also reduced in the P407 rats (0.032 ± 0.009 P407 vs. 0.043 ± 0.007 mL/s/g controls, p < 0.05). P407 treatment resulted in increased recovery and decreased PS product of paracetamol following a single pass through the isolated perfused liver. This is consistent with exclusion of paracetamol from the space of Disse due to defenestration of the LSECs.
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