VASCULAR EVENTS AND VOLUME CHANGES IN THE TURTLE'S LIVER SURVIVING IN AN ONCOMETER

Abstract

An oncometer suitable for surviving small organs is descr.; also the preparation of a lobe of the turtle''s liver and the manner of placing it in the oncometer without serious interruption of perfusion. Expts. are descr. with this prep. in the oncometer. during which marked vol. changes of the organ together with changes in rate of hepatic outflow are evoked with acetyl-[beta]-methylcholine and adrenalin-HCl. These vol. changes are graphically recorded. A method of estimating inflow vols. for short-lasting time units, synchronous with observed outflow vols., is descr. and its implications and validity discussed. By this method of estimating inflow vol. and comparing the difference between inflow and outflow vols. it appears that in response to a choline drug the latter may be as much as 50% greater or less than the former. This difference alone would represent an enormous difference between input and output of substances for an organ (during identical time units) into the general circulation, and therefore may play an important role in the body economy. In response to acetyl-[beta]-methyl-choline, injected into the portal inflow, the changes in vol. among 10 preps. was usually a decrease, which at its maximum varied from 0 to 21.7% of the liver preparation''s vol. at start. This decrease is usually followed by an increase during recovery that often is greater than the decrease evoked. In response to epinephrin the change in liver vol. also tends to be negative in character but perhaps to a somewhat lesser extent. Among 9 different preps. the maximum response in 2 cases was positive and of 16.5 and 9.3% respectively; in the 7 other cases the maximum response was negative, the decreases in vol. varying from 1.3 to 22.8%. Several attempts were made to reverse the perfusion direction so that fluid would flow into the hepatic vein and out of the portal vein, but never with any success. The precautions taken against clots and air emboli collecting in the vascular spaces were so thorough that it is considered most improbable that the failure can be attributed to emboli acting as one-way valves. No search has yet been made for venous valves however and the explanations for the failure are held in abeyance.