NEUTRON EFFECTS ON ANIMALS 67 



Rabbit serum was prepared from blood (2 to 3 cc.) obtained by heart 

 puncture. Male animals weighing about 6 pounds were employed; they 

 had access at all times to Purina Rabbit Chow and water. 



A description of the dogs from which serum samples were obtained will 

 be found elsewhere (7). 



Irradiation. The animals were exposed to whole body neutron radia- 

 tion. The procedure used in this Laboratory has been described by 

 Enns etal. (8). 



Alkaline Phosphatase Estimation. The method of Huggins and Talalay 

 (9) was used with minor modifications. One-fourth the amounts of test 

 solution and reagents specified by these authors was used in flat-bottom 

 colorimeter tubes (14 x 9(5 mm.) in conjunction with a Klett-Summerson 

 photoelectric colorimeter. Blank and experimental determinations were 

 identical except that no phonolphthalein phosphate was used in the buffer 

 employed for the former. 



In the case of rat serum, samples were made up to twice their original 

 volume with distilled \\ater immediately before use; in addition, some 

 highly active samples recjuired twofold dilution of the phenolphthalein 

 color with distilled water before a reading could be made. One hour was 

 used for incubation at 37°C'. and activity is expressed in terms of one-hour 

 units per 100 cc. of serum (9). 



With sera of low activity (rabbit, dog) no dilution was required. An 

 incubation time of two hoiu's was employed and the activity is gi\-en in 

 terms of two-hour units per 100 cc. (9). 



The use of chloroform in the alkaline buffer-substrate solution as speci- 

 fied by Huggins and Talalay was found to jneld values for normal rat serum 

 which were somewhat low when compared with those foimd in the absence 

 of this agent. The inhibition amounted to 13 to Ki per cent; no difference 

 was found in the slopes of the unit curves for each solution nor in the pH 

 of each after the usual propoi-tion of serum had been added. This apparent 

 inhibitory action of chloroform was not encountered in the woi-k on rabbits. 

 Since these observations were first made after most of the estimations on 

 rat sera had been performed, recoided values in this study are based on 

 the use of buffer-substrate solutions saturatetl with chloroform. 



SERUM ALKALINE PHOSPHATASE ACTIVITY IN RATS 



The serum alkaline ph()si)hatase activity has been investigated in nine 

 groups of female rats (Tabl(> T). The animals in eight groups were previ- 

 ously exposed to a single dose (5() n) of neutron radiation in Box No. 7 (8) 

 while the remaining group of norm.al animals served as controls. Enzyme 

 estimations were made on the serum from each animal at the time of sacri- 

 fice, which occurred on \arious days after the irradiation period. 



