EFFECTS OF DIET POOR IN INORGANIC SALTS ON CERTAIN ORGANS AND BLOOD OF YOUNG RATS

Abstract

The following experimental rations were used: Diet 1, casein 18%, starch 51%, lard 27%, salts 4%; Diet 2, casein 18%, starch 55%, lard 27%; Diet 3, casein 35%, starch 27%, lard 30%, salts 8%; Diet, 4, casein 45%, starch 13%, lard 32%, salts 10%. The plan was to compare measurements and composition of the various organs in the group given the low salt ration with other groups of animals of the same age or body weight but with different nutritive history during the experimental period of 40 days. The "low salt" group, consisting of 26 rats weighing from 41 to 49 gm., was given diet 2 without added salts at weaning and in all but 1 case the body weight was maintained at 45 [plus or minus] 5 gm. throughout the experimental period. Occasionally the weight of a rat in this group dropped below the 40-gm. limit but administration of the control diet containing salts always raised the weight level above 40 gm. within two days. The "physiological" control group comprising 20 animals was killed and autopsied at weaning when they weighed 40-45 gm. These were normal rats of the same body weight as that maintained in the "low salt" group. The "chronological" control group consisted of 12 rats which had been given diet 1 at weaning and which grew normally on this ration for 40 days. There were thus available normal animals of the same age as that of the experimental group. The "low calorie" control group including 10 rats maintained at the weaning weight of 40 to 45 gm. for the 40-day experimental period by limiting the quantity of diets 3 and 4 which are so adjusted that, in spite of the decrease in total calories provided when 1 to 2.5 gm. of the food are fed, the absolute quantity of both the indispensable protein and salts is adequate for normal growth of a rat weighing 40-45 gm. At the beginning of the experimental period this group required about 2.5 gm. of food per day and diet 3 was used; later the energy requirement for maintenance of body weight decreased to approximately that furnished by 1 gm. of food and then diet 4 was fed; both rations yield about 5 calories per gm. This group served as a control on the effects of stunting per se, apart from any qualitative deficiency in the ration. The "low salt" splenectomized group comprised 10 rats, splenectomized at weaning and maintained thereafter on diet 2 during the 40-day experimental period. Young rats maintained for 40 days on an experimental ration deficient only in ash do not increase in body weight. The body and tail lengths of such rats at the end of the experimental period are greater than those of normal rats of the same body weight. The leg bones are heavier than those of normal rats of the same weight, the increase being largely accounted for by the higher content of organic residue. The fresh weight of the kidneys of the experimental animals is strikingly greater than that of normal rats of the same weight. The concentration of moisture, ash and organic solids of the kidney is similar to that of normal rats of the same weight rather than age. The fresh weight of the spleen is diminished and this organ is more like that of the normal weight controls than age controls. There is a polycythemia, the cells being smaller than normal and the total hemoglobin of the blood less than normal.