Liver Perfusion in the Study of Hormone Effects on the Ionic Content and Membrane Potential of Liver Cells

Factors responsible for the success of canine liver perfusion are reviewed along with the description of the method used by the authors; emphasis is placed on the avoidance of anoxia, perfusion with blood by the hepatic artery and the portal vein, use of optimal values for haematocrit, pCO2 and temperature. The validity of this method of perfusion is established by biochemical tests but also by its ability to support the viability of livers before transplantation. The monitoring of the perfusion is obtained with an on line digital computer gathering data from autoanalyzers, transducers (temperature, pressure) and from intracellular microelectrodes for the measurement of the membrane potential of the liver cell. Various applications of this system to the study of ionic movements are described. Non-hormonal factors, such as temperature or pH changes modify the ion concentration and the membrane potential; some of the mechanisms involved are briefly discussed. Epinephrine injection produces by stimulation of the α receptor an hepatic potassium loss coupled with an equivalent sodium gain which are concomitant to a marked depolarization. These phenomena can be related to an increase in membrane permeability to the sodium ion. Comparisons are made between the stimulation of a and β adrenergic receptors. The effect of insulin on potassium uptake is studied during liver perfusion and in vivo in order to demonstrate antagonism between insulin on one hand and glucagon and cyclic AMP on the other hand. In conclusion, liver perfusion offers some advantage over in vivo or other in vitro techniques but the method employed must maintain the liver in perfect functional condition. The measurement of membrane potential could be used to evaluate the viability of the perfused liver.