Table 22. — Kidney weights in fasted and nonfasted rats maintaining weight at different ages on stock, SP 



8 HVO, and SPE diets 





Rats 



Average 

 age 



Average 

 weight 



at 

 death > 



Kidney weight 



Kidney 

 to body 

 weight 



Rats with kidneys weighing — 



Condition, diet, and 

 age (days) 



Average 



Range 



Less 



than 



1.50 



grams 



1.50 to 



1.99 



grams 



2.00 to 



2.99 



grams 



3.00 

 and 

 over 



Fasted rats 



Stock: 



Less than 200. _ . . 

 200 to 299 . 



Number 

 4 

 15 

 6 

 5 

 8 



6 



8 



7 



14 



7 



8 



14 



11 



15 

 11 

 5 

 7 

 11 

 11 



5 



6 



23 



5 

 18 

 29 



Days 

 160 



248 

 382 

 436 



727 



252 

 353 



457 

 546 



252 

 348 

 455 

 530 



148 

 258 

 376 

 465 

 538 

 679 



154 

 248 

 332 



154 

 277 

 330 



Grams 

 381 

 447 

 428 

 436 

 410 



502 

 541 

 600 

 680 



552 

 588 

 616 

 624 



390 

 466 



482 

 486 

 490 



457 



521 



532 

 636 



520 

 613 

 614 



Grams 

 1. 34 

 1. 58 

 1.58 

 1. 54 

 1. 66 



1. 41 



1.57 



1. 63 



2. 17 



1. 69 



2. 44 

 2. 29 

 2. 34 



1. 41 



1. 67 



2. 01 



1. 87 



2. 15 

 2. 23 



2. 08 

 2. 02 

 1. 88 



1. 92 



2 22 



3! 01 



Grams 

 1. 12-1. 50 

 1. 13-1. 92 

 1. 17-2. 02 

 1. 32-1. 82 

 1. 21-2. 10 



1. 24-1. 74 

 1. 23-2. 39 

 1. 19-2. 59 

 1. 43-5. 24 



1. 46-1. 81 

 1. 60-3. 99 

 1. 47-4. 50 

 1. 76-3. 82 



. 98-1. 86 

 1. 38-2. 01 

 1. 34-2. 96 

 1. 07-2. 70 

 1. 41-3. 61 

 1. 45-2. 93 



1. 79-2. 54 

 1. 43-3. 32 

 1. 41-2. 71 



1. 76-2. 17 

 1. 49-4. 19 

 1. 69-8. 88 



Percent 

 0. 35 

 . 35 

 . 36 

 .34 

 . 37 



.28 

 . 29 

 .26 

 .32 



.31 

 . 41 

 .37 

 .36 



.36 

 .36 

 . 41 

 .38 

 .43 

 . 47 



. 40 

 .37 

 .30 



. 37 

 .37 



.49 



Percent 

 75 

 27 

 33 

 60 

 25 



83 

 50 

 57 



7 



14 

 



14 

 



73 

 27 

 20 

 14 

 9 

 9 





 17 

 13 





 6 

 



Percent 

 25 

 73 

 50 

 40 

 62 



17 



38 

 29 

 57 



86 

 38 

 36 

 36 



27 

 54 

 40 

 57 

 54 

 9 



60 

 50 

 61 



60 

 22 

 38 



Percent 

 

 



17 

 



12 





 12 

 14 

 29 





 50 

 29 



54 





 18 

 40 

 29 



27 

 82 



40 

 17 

 26 



40 

 67 

 38 



Percent 

 

 



300 to 399 ._- 







400 to 499 







500 and over 

 SP 8 HVO: 



200 to 299 . 





 



300 to 399. 







400 to 499 -._ 







500 to 599 . .__ 



7 



SPE: 



200 to 299. 







300 to 399. . 



12 



400 to 499_- 



21 



500 to 599. -_ 



9 



Nonfasted rats 



Stock: 



Less than 200 _ 



200 to 299 _ __ 





 



300 to 399. 







400 to 499.. 







500 to 599 



9 



600 and over . 

 SP 8 HVO: 



Less than 200___ . . 

 200 to 299 . _ 











17 



300 to 399 . _ 







SPE: 



Less than 200 



200 to 299.. ___ . _ 





 6 



300 to 399 _._ 



24 







1 Weight before 17-hour fast. 



the percentage of rats with large livers and not to 

 an occasional excessively heavy liver. 



The increasing difference with age between both 

 the kidney and the liver weight of fasted and 

 nonfasted animals suggests that a slowing of the 

 metabolic processes has occurred in the older rats, 

 resulting in a temporary enlargement of these 

 organs, which can still return to normal after a 

 17-hour fast. 



In fasted rats fed SP 8 HVO diet, livers showed 

 a consistent tendency to increase in size with age, 

 in contrast to the relatively constant values ob- 

 served for the weights of livers from comparable 

 stock rats. The livers represented 2.1 percent of 

 body weight, with no apparent influence of age 

 on this relationship. The increase in liver size 

 with age, therefore, seems to be due chiefly to the 

 tendency for adult rats fed SP 8 HVO diet to 

 continue gaining in body weight with age. 

 Although the livers from these animals weighed 



more, on the average, than those from stock rats, 

 they were significantly smaller in relation to body 

 weight (P<0.01). There was no evidence that 

 age was a factor within the limited range for which 

 data were available. 



Livers from nonfasted rats averaged 20.3 grams 

 in weight, 8 grams heavier than those from fasted 

 rats of corresponding age. In nonfasted rats 

 fed this diet, large livers were observed even in 

 rats less than 200 days old. In contrast to the 

 stock rats, the livers from these nonfasted SP 8 

 HVO rats tended to represent a smaller percentage 

 of the body weight with increasing age, 4.5 

 percent for rats under 200 days, and 3.1 percent 

 for those between 300 and 400 days of age. 



On SPE diet, the livers from fasted rats were 

 larger than those from rats fed stock or SP 8 HVO 

 diets, averaging 21.0 grams in weight and 3.4 per- 

 cent of body weight. The range of values was 

 wide, from 12.8 grams for the smallest liver to 31.8 



39 



