Protein metabolism in growing rats. II. Serum proteins and blood complement in relation to age and dietary protein level

Abstract

A study of serum complement levels, hematocrit values, total serum proteins and electrophoretic patterns on cellulose acetate has been inade in young al­ bino rats fed on diets of three different levels (4 and 20 % casein and 9 % ve­getable protein) during periods of 15,20 60 and 90 days from weaning.

Hematocrit values increased with age independently of dietary protein. Total serum protein increased rapidly during the first month in those groups fed on diets of 20% casein and 9% vegetable protein. Animals on 4% casein diet had significantly lower values than the other diet and similar to those sacrifieed at weaning during the first two month.

Similar behavior was found in serum albumin, which suggests depletion of protein reserves in the 4% casein groups. 

Beta and gamma globulins were also lower in protein deficient rats, while alpha-globulins showed no differences in relation to dietary proteins. In the three diet groups, alpha-3-globulins increased progressively with age, to reach valúes of 300 % greater at 90 days from wean­ing; alpha-2-globulin did not vary with age and alpha-i-globulins showed a slight increase in the first 30 days only.

Serum complement level was very low at weaning and increased by about 150- 300 % during the first 15 days. At the end of the first month, animals on 20 % cascin and 9 % vegetable protein diets had levels similar to those of adults, while those on 4 % casein diet showed significantly lower levels, similar to the weaning group. At 60 and 90 days after weaning, serum complement levels was similar in the three diet groups. No correlation was found between serum complemeut level and concentration of se­rum protein fractions.