necessarily accompanied by fatty livers. There 

 was some indication with other than SPE diets 

 that large livers tended to be associated with 

 kidney damage and that changes in the liver with 

 age might be important in the production of 

 kidney damage even though the liver itself showed 

 no evidence microscopically of damage. On SPE 

 diet alone or with added supplements, liver fat 

 was high at a relatively early age, often in rats 

 with apparently normal kidneys. The infiltration 

 of the liver with fat that was observed with SPE 

 rats may, however, accelerate kidney changes. 

 The tendency to enlarged, damaged kidneys on all 

 diets suggested an inherent kidney weakness in 

 the BHE strain of rats. It is conceivable that an 

 excessive load may be placed on the kidneys be- 

 cause of improper functioning of the liver resulting 

 from some defect in certain enzyme systems 

 responsible for the normal activity of this organ. 

 Differences in the accumulation of fat in the 

 livers of BHE and Wistar rats when fed SPE diet 

 under identical conditions provide evidence sug- 

 gesting inherent differences in the metabolic proc- 

 esses involved in the utilization of this diet by 

 these two strains of rats. 



Serum cholesterol 



Serum cholesterol measurements were usually 

 made on the blood from fasted rats, and only the 



results with fasted animals are included in this 

 section. 



Kats maintaining weight on stock, SP 8 

 HVO, and SPE diets.- — The influence of age and 

 diet on cholesterol levels in the sera from rats 

 maintaining weight on stock, SP 8 HVO, and SPE 

 diets is summarized in table 65. Age appeared 

 to exert no influence on the serum cholesterol levels 

 or rats fed stock diet. A cholesterol level of 114 

 mg./lOO ml. was obtained for a 976-da3 T -old rat fed 

 this diet. Cholesterol values were below 150 mg./ 

 100 ml. in 80 percent of the sera analyzed. On 

 SP 8 HVO diet, serum cholesterol levels were 

 similar to those on stock diet when the age of the 

 rats was less than 500 days. In rats more than 

 500 days old, however, only 43 percent of the 

 cholesterol values were below 150 mg./lOO ml. and 

 3 of the annuals in this group had sera containing 

 more than 200 mg./lOO ml. On SPE diet, serum 

 cholesterol levels were high even in the youngest 

 group of rats, and were consistently higher than 

 150 mg./lOO ml. for all age groups. Values ex- 

 ceeding 200 mg./lOO ml. were a frequent finding, 

 and 9 of these SPE rats had serum levels exceeding 

 300 mg./lOO ml. The high serum cholesterol levels 

 in rats 300 to 399 days of age seem to be another 

 indication that this period is a critical one in the 

 response of rats to SPE diet. 



Table 65. — Influence oi diet and age on serum cholesterol levels in rats maintaining weight on stock, SP 8 



HVO, SPE, SPM, SPB, and SPPB diets 





Rats 



Average 



Serum cholesterol 



Diet and age of rats 







Rats with cholesterol levels 



of— 



(dars) 





age 



Average 



Range 





























Less than 



150 to 199 



200 to 299 



300 mg./ 













150 mg./ 



mg./lOO 



mg./lOO 



100 ml. 













100 ml. 



ml. 



ml. 



and over 





Number 



Days 



Mg./lOO ml. 



Mg./lOO ml. 











Stock: 



















Less than 300. 



19 



229 



120 



79-217 



79 



16 



5 







300 to 499 _.. 



5 



6 



410 

 691 



117 



127 



97-151 

 107-179 



80 



83 



20 

 17 





 







500 and over. _ 







SP 8 HVO: 



















Less than 300 



6 



252 



103 



90-117 



100 















300 to 399 



S 



353 



122 



81-185 



( 



25 











400 to 499 _ . ... 



6 



457 



131 



112-154 



83 



17 











500 to 599 



14 



546 



166 



99-270 



43 



36 



21 







SPE: 





Less than 300 



7 



252 



199 



157-240 







57 



43 







300 to 399 



7 



353 



351 



178-670 







14 



43 



43 



400 to 499 



14 



455 



232 



152-402 







43 



43 



14 



500 to 599 



1 1 



530 



287 



197-432 







9 



55 



36 



SPM: 



















Less than 400 



6 



304 



118 



102-128 



100 















400 to 599 



6 



512 



164 



87-265 



50 



17 



33 







SPB: 





Less than 400 - 



6 



304 



103 



SO-152 



83 



17 











400 to 599 



6 



513 



163 



79-243 



50 



17 



33 







SPPB: 



















Less than 400. . 



6 



289 



135 



95-236 



83 







17 







400 to 599 . 



11 



530 



221 



129-343 



9 



36 



36 



18 



78 



