Table 67. — Serum cholesterol levels of rats with kidneys of different weights on stock, SP 8 HVO, SPE, 



SPM, SPB, and SPPB diets 



Diet 



Rats 



Kidneys less than 

 1.80 grams 



Rats 



Kidneys 1.80 to 2.19 

 grams 



Rats 



Kidneys 2.20 grams 

 and over 





Average 

 weight 



Average 

 cholesterol 



Average 

 weight 



Average 

 cholesterol 



Average 

 weight 



Average 

 cholesterol 



Stock 



Number 

 31 

 34 

 27 

 13 

 15 

 18 



Grams 

 1.49 

 1.47 

 1.52 

 1.33 

 1. 44 

 1. 46 



Mg./lOO ml. 

 108 

 114 

 192 

 115 

 113 

 147 



Number 



6 



10 



10 



7 



1 



13 



Grams 

 1.94 

 1. 95 

 1. 91 

 1. 95 

 1. 86 

 1.99 



Mg./lOO ml. 

 142 

 157 

 280 

 187 

 241 

 222 



Number 



4 



10 



76 



3 



8 



10 



Grams 



2. 78 



3. 88 

 5. 51 

 3. 06 

 3.32 

 4.45 



Mg./lOO ml. 

 225 



SP 8 HVO 



SPE 



228 

 343 



SPM 



397 



SPB 



302 



SPPB 



304 







to accompany the small normal kidneys from rats 

 fed SPPB diet. The highest levels to accompany 

 kidneys in this weight range were those from rats 

 fed SPE diet. Kidneys weighing between 1.8 

 to 2.2 grams frequently showed some signs of 

 damage, chiefly evidenced by the presence of 

 hyalin casts. Cholesterol levels accompanying 

 kidneys in this weight range were consistently 

 higher than those found in rats with small kidneys. 

 Cholesterol values in rats with badly damaged 

 kidneys exceeding 3.0 grams in weight were 

 generally high, but neither kidney size nor the 

 types of kidney damage observed showed any 

 quantitative relationship to the extent that the 

 serum cholesterol was elevated. 



A further consideration of the cholesterol data 

 suggests that the influence of age on serum levels 

 may be related chiefly to the increase with age in 

 the number of rats with enlarged damaged kidneys. 

 Evidence for this is seen in the data summarized 

 in table 68 for rats fed the semipurified diet, 

 where the results for rats with damaged kidneys 

 have been excluded. The main difference between 

 the results in this table and in table 65 lies in the 

 results for rats 500 days and older. The 5 animals 

 in this age group with small normal kidneys had 

 an average cholesterol value of 120 mg./lOO ml. 

 similar to that found for younger rats, in contrast 

 to 166 mg./lOO ml. (table 66) for all 14 animals in 

 this age group. 



Table 68. — Serum cholesterol levels of rats with 

 normal kidneys at different ages on SP 8 HVO 



diet 



Average aj 



ie (days) 



Rats 



Cholesterol 





Average 



Range 



252 



354 _ 



Number 

 6 

 6 

 5 

 5 



Mg./lOO ml. 

 103 

 119 

 133 



120 



Mg./lOO ml. 

 90-117 

 84-164 



460 



112-154 



549 ... 



99-150 







Serum cholesterol in littermates. — No con- 

 sistent relation of serum cholesterol to liver size, 

 liver fat, and adrenal or thyroid size was observed. 

 There was some indirect evidence that the wide 

 range of serum cholesterol levels was due in part 

 to differences in inherited characteristics in the 

 mixed strain of rats under investigation. Litter- 

 mates were used in each of the experimental series 

 for comparison of the various dietary regimens, 

 but relatively few data were available to compare 

 the response of littermates fed the same experimen- 

 tal diet. One series with SPE diet provided some 

 data that permitted a direct comparison of the 

 response of littermates to this diet under strictly 

 comparable conditions. In table 69 are sum- 

 marized the findings for two littermates from each 

 of four litters. All were sacrificed at about 550 

 days of age. Data are included not only for serum 

 cholesterol levels but also for the organ weights of 

 these rats. Only one of the animals had lost more 

 than 100 grams when sacrificed. Although the 

 range of serum cholesterol values for the individual 

 rats in the four litters was wide, varying from 152 

 to 432 mg./lOO ml., the serum levels for littermates 

 were relatively close. In contrast, organ weights 

 of individual rats varied considerably even for 

 littermates. 



Rats fed other experimental diets. — -In 

 table 70 are summarized limited data on serum 

 cholesterol levels in rats fed the other experimental 

 diets. Most of the data were for sick or moribund 

 rats that were losing weight at the time of sacrifice. 



The wide range of values and the tendency to 

 elevated serum cholesterol values observed in 

 SPE rats were also apparent in rats fed the various 

 supplemented SPE diets. No significant differences 

 were observed in the serum cholesterol levels on 

 any of these diets. Most of these rats had lost 

 more than 100 grams before sacrifice and had large 

 damaged kidneys. A comparison of the serum 

 levels in rats that were maintaining weight might 

 show differences not apparent in these moribund 

 animals. 



When the level of HVO was increased from 8 to 

 16 percent, the average serum cholesterol level 



80 



