Table 36.— Kidney and liver weights in two strains of rats at terminal age from parents fed two stock diets t 



with young fed SP 8 HVO and SPE diets 



Strain and diet 



Rats 



Average 

 age 



Average 



weight 



loss 



Kidney weight 



Liver weight 





Average 



Range 



Average 



Range 



B HE rats 



Parents fed BHE stock diet: 

 Offspring fed — 



SP8HV0 



Number 

 11 

 14 



10 



9 



5 



9 



10 



Days 

 571 

 438 



739 

 633 



886 

 703 

 435 



Grams 

 136 

 151 



108 

 80 



75 



85 



Grams 

 3. 76 

 8.24 



2. 00 

 2.35 



1. 22 



2. 41 

 5. 14 



Grams 



1. 70- 7. 80 



2. 68-13. 3 



1.34- 4. 11 

 1. 60- 4. 34 



1. 12- 1. 40 



1. 04- 4. 07 



. 99-10. 4 



Grams 

 16. 9 

 21. 4 



1 13. 7 (8) 

 18. 9 



10. 2 

 12. 2 

 1 21. 6 (9) 



Grams 

 10. 0-24. 7 



SPE 



Wistar rats 



Parents fed Wistar stock diet: 

 Offspring fed — 



SP 8 HVO 



15. 3-38. 7 

 9. 0-24. 6 



SPE 



15. 0-21. 9 



BHE rats 



Parents fed Wistar stock diet: 

 Offspring fed — 



Wistar stock 



9. 6-12. 4 



SP 8 HVO 



10. 0-15. 7 



SPE._ 



13. 7-34. 7 







1 Numbers in parentheses indicate the number of animals when differing from that listed in column 1. 



rats. The livers from Wistar rats fed SPE diet 

 tended to be larger than those from the same 

 strain fed SP 8 HVO diet. 



BHE rats from parents raised on the stock diet 

 of the Wistar rats showed differences in kidney 

 and liver weights with SP 8 HVO and SPE diets 

 that were similar to those found when the parents 

 were raised on regular stock diet. The results 

 agree with the histological findings, and provide 

 further evidence that the dietary history of stock 

 Wistar rats was not responsible for differences in 

 the response of BHE and Wistar rats to diet. 



Discussion. — Much of the information in the 

 literature on kidney weights in the rat has been 

 based on studies during the period of rapid growth 

 or for the young adult rat. There appears to be 

 a tendency for the right kidney to be somewhat 

 larger than the left kidney (4, 123), although the 

 differences observed were small (3 to 5 percent). 

 There has been general agreement that the weight 

 of this organ is closely related to body weight, 

 but the value for this relationship has been found 

 to vary with the strain of animal under investiga- 

 tion. The values tabulated in Donaldson's refer- 

 ence tables for Wistar rats (50) were obtained 

 by using the formula of Hatai (86) relating kidney 

 to body weight. For male rats weighing 450 

 grams, the value recorded for the weight of two 

 kidneys was 3.5 grams or 0.78 percent of body 

 weight. Freudenberger (70) has reported kidney 

 weights with a similar relationship to body weight 

 for male Wistar rats 1 year old. For comparable 

 rats of the Long-Evans hybrid strain of Norway 

 rats, the average kidney weight represented a 

 somewhat smaller percentage of the body weight, 



0.69. Addis and Gray (4)> using a log log relation 

 between body and kidney weight, have developed 

 an equation for the Slonaker strain of rats and 

 have presented standards for kidney weights of 

 rats with body weights up to 400 grams. On 

 the basis of the standards for the Slonaker strain, 

 animals weighing 400 grams would have kidneys 

 weighing 0.54 percent of their body weight. 



The results reported in this publication provide 

 no information on changes in kidney size in the 

 young growing rat. For fasted adult rats under 

 300 days of age, kidney weights, when considered 

 in relation to body weight, were within the range 

 reported by other investigators. 



The influence of feeding various dietary 

 combinations throughout life on the kidney size 

 of the rat has received relatively little attention 

 to date. Many of the available reports relating 

 diet to kidney size have dealt with short-time 

 feeding studies, often under extreme conditions 

 producing acute changes. The emphasis has been 

 chiefly on the influence of dietary protein on 

 kidney size, and there has been general agreement 

 that kidney size is increased with increasing 

 levels of protein. 



Osborne, Mendel, Park, and Winternitz (150) 

 observed an invariable increment in the size of the 

 kidney when the casein content of the diet ex- 

 ceeded 50 percent. This gain in kidney weight 

 often amounted to 50 percent or more above the 

 normal weight. When the casein level exceeded 

 75 percent, unmistakable evidence of kidney 

 enlargement was found within 8 days. Equally 

 striking changes were observed when rats were 

 fed a diet containing 80 percent "meat residue." 



50 



