Balance of Net Base in the Rat. II. Reference Values in Relation to Growth Rate

Abstract

An investigation of mineral and net base balances in weanling, adolescent, food-restricted, and adult Wistar rats is presented. Supplementary studies included whole carcass analysis and measurements on isolated organs and skeleton preparations. The results show that the growing rat is in a state of positive net base balance due to dietary net base being deposited, along with calcium, magnesium, and phosphate, in the skeleton. Rates of gastrointestinal absorption of net base, calcium, magnesium, and phosphorus appeared closely interdependent and rates of retention were subject to <i>extrarenal</i> control. The sum of balances of magnesium and calcium was tightly correlated to the rate of weight gain. The results prove studies of the balance of net base in the young growing rat to be technically feasible and constitute a system of reference values for animals on a standard food preparation.