Cell injury and protection in long-term incubation of liver slices after in vivo initiation with paracetamol: cell injury after in vivo initiation with paracetamol

Diabetes and hypertriglyceridemia modify the mode of acetaminophen-induced hepatotoxicity and nephrotoxicity in rats and mice

Certain disease conditions can modify drug-induced toxicities, which, in turn, may cause a medication-related health crisis. Therefore, preclinical investigations into the alterations in drug-induced toxicities using appropriate disease animal models are very important. This paper reviews the reported data related to the effects of diabetes and hypertriglyceridemia, common lifestyle-related diseases in a modern society, on acetaminophen (APAP)-induced hepatotoxicity and nephrotoxicity in rats and mice. It has generally been reported that diabetes protects rats and mice from APAP-induced hepatotoxicity and there are several reports that help to speculate on the effects of diabetes on APAP-induced nephrotoxicity. In fructose-induced hypertriglyceridemic rats, hepatotoxicity of APAP becomes apparently less severe, whereas nephrotoxicity of APAP becomes significantly more severe. The mechanisms of alteration of APAP-induced hepatorenal toxicity under diabetic and hypertriglyceridemic conditions are also discussed in this paper.

Structural and functional integrity of precision-cut liver slices in xenobiotic metabolism: a comparison of the dynamic organ and multiwell plate culture procedures

1. Objectives were two-fold: (1) to compare the viability of precision-cut liver slices in two culture systems, namely the dynamic organ and the multiwell plate; and (2) to evaluate whether increasing the number of slices per incubation results in a proportional increase in the extent of metabolism. 2. With both culturing systems, the major products of 7-ethoxycoumarin metabolism were the sulphate and glucuronide conjugates of 7-hydroxycoumarin with very low levels of the free compound. When the multiwell plate procedure was used, metabolism increased linearly for at least 10 h, whereas it tended to plateau after 6 h in the dynamic organ culture system. At preincubations > 10 h, significantly more metabolism of 7-ethoxycoumarin was seen in the slices cultured using the multiwell system compared with the dynamic organ system. 3. Morphological evaluation employing light and electron microscopy revealed that liver slices incubated using the multiwell system were structurally better preserved compared with those incubated using the dynamic organ system. 4. Using the multiwell system, increasing the number of slices per incubation from one to two resulted in only a modest increase in the metabolism of 7-ethoxycoumarin. The rate of metabolism of this substrate was much higher with one liver slice when expressed per mg homogenate protein. 5. It is concluded that (1) the multiwell plate culture system for culturing slices is superior to the dynamic organ system in studying the metabolism of xenobiotics following long-term incubations, (2) increasing the number of slices per incubation does not result in a corresponding increase in the rate of metabolism, and (3) in both culture systems optimal viability appears to be within 24 h of incubation.

Protection in the late stages of paracetamol-induced liver cell injury with fructose, cyslosporin A and trifluoperazine

A fixed combination of the three components, fructose, cyclosporin A and trifluoperazine (FCAT), was found to protect in the late stage of paracetamol-induced liver cell injury both in vivo and in an in vivo/in vitro system. Rats pre-induced with phenobarbitone were given a paracetamol dose of 1 g/kg i.p. The combination of FCAT was given orally 3 h or 3 and 8 h after paracetamol and was able to afford protection as seen by measurements of plasma alanine transaminase (ALT) levels at 24 h. In the in vivo/in vitro system, rats pre-induced with phenobarbitone were dosed with paracetamol 1 g/kg i.p. to initiate injury and liver slices were then taken 3, 4 and 5 h later. The liver slices were then incubated for up to 18 h with the protective agents (FCAT) and the progression of injury followed. Injury was assessed by lactate dehydrogenase (LDH) leakage into the medium and potassium content of the slices. FCAT significantly reduced the injury even as assessed after 5 h in vivo initiation and 18 h progression in vitro. Mitochondrial membrane potential was also maintained in the FCAT-treated liver slices from paracetamol-treated rats as seen by the ability to maintain a gradient of triphenyl methyl phosphonium (TPMP+) between the cell and external medium. All three compounds are required for protection, indicating that more than one event is critical to the survival of the cell and each target point needs to be protected for effective long-term cell survival. The in vivo/in vitro system has been found to give a better comparability to the in vivo situation than injury models that take 6 h or less.