268 



H. J. CURTIS AND CATHRYN CROWLEY 



METHODS 



Mice of the Charles River CD 1, specifically pathogen-free, strain were 

 used for the experiments which were begun when they were 2 months old. 

 Mercuric chloride was administered by stomach tube in the first experimental 

 group at the rate of 40 mg/kg of body weight, and at the rate of 20 mg/kg in 

 the second. These doses were administered once a week for four consecutive 

 weeks. Thereafter the mice were set aside for a period of 4 months. At that 

 time the animals were subjected periodically to 24-hour water deprivation, 

 and immediately thereafter pooled urme samples were collected from each of 

 the experimental and control groups. These were analysed for protein by 

 means of the Biuret reaction (Gornall et al, 1949). Also after the 24-hour 

 water fast, urine samples were expressed from 5 individual mice in each group 

 and the specific gravity was measured in a linear density column (Linderstrom 

 Lang and Lantz, 1938). 



RESULTS 



The results of the protein Biuret analyses are shown in Fig. 1. Three to four 

 months after the administration of mercuric chloride, the protein output 

 began to climb in the experimental mice reaching maximum output in 5-6 

 months. 



ro 



.10-0 - 

 0) 90 

 1 8-0 



7-0 



1 6-0 

 "I' 5-0 

 .s 4-0 



3-0 

 2-0 

 1-0 



o 



i 



1 \ ] \ \ r~r 



After 24 hr water fast 

 40 mg/kg HgClg 



1 I I I I I r 



20mg/kg HgCl2 



Control 



HgClj 

 stopped 



J L 



60 



ICO 



220 260 300 340 

 Age (days) 



380 420 460 



Fig. 1. Variation of protein concentration with age for normal and mercury-poisoned mice. 



In Fig. 2 the results of the specific gravity tests are shown. As indicated 

 by the control curve, the abihty of the normal kidney to concentrate urine 

 decreases with age. For the pomts tested up to about 9 months of age the 

 experimental group are less able than the controls to concentrate the urine. 



