72 NEUTRON EFFECTS ON ANIMALS 



follow rather closely the decrease in food intake as observed by Ross and 

 Ely (10) in rats irradiated under similar conditions. It can be pointed out, 

 on the basis of the results obtained by Weil and Russell (11) and by Gould 

 (12) on the effects of fasting, that a lack of fat absorption in rats would be 

 expected to result in a lowered alkaline phosphatase activity in serum. 

 Since the food intake data as well as other studies (10) point to a disruption 

 in food assimilation after irradiation and since this disturbance is closely 

 associated with the lowered enzyme activity, it is considered probable 

 that the latter may be largely, if not wholly, due to this one factor. 



In respect to the effects of neutron irradiation on the enzyme level in 

 the rabbit, further investigation will be necessary before any conclusions 

 can be made. The limited data, how^ever, do indicate that irradiation 

 employed under conditions which effect a decrease in the serum enzyme 

 activity in the rat may result in a similar but more prolonged decrease 

 in the rabbit enzyme. On the basis of the different energy values assigned 

 to the radiation in Box Xo. 4 and Box No. 7 (8), it is further indicated 

 that the enzyme decrease found in rabbits using a dose of 56 n at the lower 

 energy levels may not occur when the same dose of higher energy neutrons 

 is employed. It is evident that these points require further investigation. 



A rise in the alkaline phosphatase activity in the serum of rabbits after 

 exposure of the head or abdomen to X-rays (approximately 600 r) was 

 observed by Iwatsuru and Xanjo (3); this rise was attributed by these 

 authors to release of the enzyme by destroyed leukocytes. It is of interest 

 to note that Wachstein (13), using a modified Gomori technique, could 

 detect no alkaline phosphatase activity in the blood cells of the normal dog, 

 although many of the polymorphonuclear leukocytes in rabbit blood showed 

 strong activity. It would appear that destruction of leukocytes could not 

 account for the increase in serum enzyme activity found in neutron- 

 irradiated dogs employed in the present study. This increase, whether it 

 be due to one or many factors, is not unusual in view of the severe bodily 

 damage (7) suffered by these animals. 



SUMMARY 



The activity of alkaline phosphatase in the blood serum of rats, rabbits, 

 and dogs has been determined before and after exposure of the animals to 

 whole body neutron radiation. 



When a dose of 56 n was employed, rats showed a 75 per cent decrease 

 in the serum enzyme level on the fourth day; essentially normal values were 

 found one week after exposure. 



Limited data indicate that rabbits when irradiated under the same 

 conditions may show a decreased serum enzyme activity; under these 

 conditions, no significant changes were noted in the activity of serum acid 

 phosphatase. 



