Metabolism studies on surviving turtle's liver

Abstract

In previous reports it has been stressed that, when inaking up balance sheets of organ metabolism from perfusates, it is important to take into the account rates of both the inflow and the outflow (v. Snyder and Tyler, '40). The present report deals with the results of experiments designed to follow the exchanges of lactic acid and glucose (copper reducing substances) between an organ and its perfusates determined upon such a basis.Livers of turtles were used, following the methods and techniques we have elsewhere described ( '40). The animals were Pseudemys elegans, well nourished and of ca. 20 em. body length. Inflow and outflow rates of perfusates were recorded continuously as well as p H of the hepatic vein outflow. During the course of an experiment samples werme taken from time to time from both the inflow and outflow paths for chemical analysis. The results were then reduced to the standard conditions of gain or loss in the hepatic vein outflow in reference to the porl-a1 vein inflow expressed as milligrams substance per minute per 100 gm. wet weight of liver. These data were finally plotted on coordinate paper.In order to leave no doubt, as to the extent to which the output rate of EL substance depends upon the varying differences of fluid outputinput rates, either a single curve plotting simply their differences (as in fig. 1, curve I) or a pair of curves, plotting the flow-rates of inflow and outflow separately (as the pair, I and 11, in fig. 2) is shown. The latter Explanatory notes i n general to all three figures. Along the abscissae the time durat'ion of the rxperiments is plotted in minutes. Along the ordinates, in terms of minutes and 100 gm. liver, are plotted: (a) rates of exchange of substances i n terms of milliliters or milligrams. ( b ) (either rates of flow, or gain or loss of rate of outflow i n reference t o rate of inflow, i n terms of milliliters per minute. In the latter case the curve is also a record of changing liver volurne. The pH of the fluid i n the hepatic vein outflow is also plotted along the ordinates. The glucose determinations are plotted as dots in full circles; lactic acid determinations are plotted as dots i n half circles. The frequency of points i n all the curves is fixed by the frequency of dumps of the tilting vessel at the hepatic vein outflow.