ISOLATED PERFrSF.D LIVER— BRAUER 



239 



relt-ntion of the choleretic at the effector sites, this response suggests that the liver 

 in some respects acts as though it were suhjected to bile stasis ; this response is not 

 too different from that seen if the organ were subjected to mechanical bile stasis. 

 The hypothermic liver, therefore, may be thought of as in "biochemical stasis" 

 under these conditions. We shall see presentl\- that this concept also describes parts 

 of the BSP handling in the liver at low perfusion temperatures. 



Our interest in hypothermia originally sprang from a concern with tlie mecha- 

 nism of bile secretion. The positive correlation of bile flow and perfusion tempera- 

 tures under controlled conditions of I)!ood How clearly separated this secretion 

 from urine — a filtration reabsorption i)roduct with a negative correlation with 

 temperature under comparable conditions." As a further outcome of our concern 

 with this problem we studied the relation between bile flow, perfusion rate or pres- 

 sure and perfusate oxygen tensions. Figure 3 shows our results insofar as they 

 relate to the problem of hypothermia. It is evident that, while at 38° C. bile flow 

 becomes dependent upon perfusion rate when this falls below 2 cc./g./mm., at 

 29° C. much lower perfusion rates can be attained without significant falling off of 

 bile flow. From our point of view this finding is in line with the results of pressure 

 chamber and of hemodynamic studies indicating that oxygen supply in relation to 

 oxygen consumption, rather than perfusion pressure or perfusate flow, is the factor 

 limiting bile flow^ under these conditions. From the point of view of the applications 

 of hypothermia to surgery or medicine, these same data afford a further illustration 

 of the protection of tissue functions against ischemia by lowering of tissue 

 temperatures. 



Finally, a few words may be in order in relation to the handling of BSP by the 

 isolated rat liver at various temperatures. After injection, BSP disappears from the 

 circulation according to a time course which is exponential for a brief period, 



100 



75 



uj 50 



_i 



m 



ui 

 > 



< 25 



UJ 



a: 



■=iPt!^A-==^ 



O 29°G 

 A 38°C 



12 3 4 5 6 7 



TISSUE PERFUSION (CQ/G/MIN) 



Fig. 3. — Bile flow-blood flow relations at ,58 C. and at 29" C. for three isolated rat liver 

 preparations. Wliole blood used as perfusate. 



