INITIAL HYPEREMIA AND BLOOD VOLUME 



415 



There is evidence that the perfusion rate of blood through the Hver * 

 may be sHghtly decreased after acute specific irradiation of the organ 

 (use of Y^° colloids). (See Fig. 1.) However, the irradiation dosage 

 must be great in order to measure an effect. After an accumulation of 

 20,000 rep in 3 days in the liver due to uptake of Y^° colloid, mice showed 

 a 30 per cent reduction in rate of uptake of chromic phosphate colloid 



1.5 



<u — 



2 1.0 



0.5 



3 X 10*'ergs/gm 



3x 10' rep 



2 X 10*^ergs/gm 

 2x10' rep 



1 X lO^ergs/gm 

 1 X 10' rep 



0123456789 

 Davs after injection of Y colloid 



Fig. 1. The circles represent the chromic phosphate disappearance constant (ob- 

 tained in mice) plotted as a function of time after the injection of a liver-localizing 

 colloid containing Y^. The open circle at zero time represents the average disap- 

 pearance constant as measured on normal non-anesthetized mice. Also included on 

 the graph are the body weight, mortality, and accumulated irradiation dose to the 

 liver. The ordinate at the right represents the radiation dose in two sets of units, 

 ergs per gram of Uver tissue and roentgens equivalent physical. The units for the 

 body-weight curve and for the per cent mortality curve are given at the beginning 

 and end of the curves. [Graph by Dobson (4).] 



by the liver, and this was divided between a reduction in phagocytic 

 efficiency and decreased liver perfusion rate. After 6-9 days these ani- 

 mals had accumulated 30,000 rep, and the combined decrease in phago- 

 cytic efficiency and circulation amounted to a 60 per cent decrease in 

 chromic phosphate disappearance. Thus for moderate irradiation dos- 

 ages very little effect would be expected in the effective liver perfusion 



* As measured by chromic phosphate disappearance. Under most circumstances 

 the clearance of chromic phosphate through the liver is greater than 90 per cent. 

 It is estimated that about half the irradiation effect noted here is a decrease in the 

 phagocytic efficiency of the liver in the removal of chromic phosphate from the 

 blood, and about half is a true decrease in the perfusion of blood through the liver (4). 



