Troubleshooting and improving the mouse and rat isolated perfused liver preparation.

Isolated Perfused Liver (IPL) model is widely performed in rats but mouse liver is used also, although a detailed description of this procedure is absent. A comparison of the different techniques used on rats and mice will be discussed in this article, associated with a detailed description of the surgical and technical aspects needed to obtain and maintain the integrity of the livers during the organ isolation and perfusion. The surgery procedures, the IPL set-up, and the evaluation of hepatic function and damage will be described in relation to both rats and mice. In particular, the heparin dosage and administration, the portal vein cannulation avoiding portal leakage, the use of supra hepatic caval vein output, and the insertion of a cannula for bile collection will be reported. For the settings, the perfusion circuit, the perfusion solution, the temperature and the flow rate will be described, with particular regard to the balance between perfusion pressure and oxygen delivery. The monitoring of liver integrity by measuring oxygen concentration and calculating oxygen delivery rate and oxygen uptake rate, and recommendations for the collection of perfusate and bile samples will be considered. Accurate pH measurement with normalization, and the perfusion portal pressure assay by a calibrated water manometer will be also reported. This work analyzes the parameters crucial to performing a correct IPL both in rat and mouse, comparing our experience with the equivalent practice from other laboratories. An updated example of IPL applications in liver toxicology and pharmacology, physiology and pathophysiology, and liver graft preservation will be briefly presented, underlining how this technique provides essential information allowing a more accurate planning of the in vivo studies.