Calcium Excretion by the Alimentary Tract.

Abstract

It is generally accepted that calcium is absorbed in the upper and excreted in the lower intestine. Since, so far as we have been able to ascertain, none of the experiments used by the various investigators has involved the use of pouches or fistulas of the various portions of the intestine in unanesthetized animals, we decided to study calcium excretion by using such a method. We believe this method has the definite advantage that every possible factor can be quite accurately controlled.

Stewart and Percival, 1 in acute experiments on cats, showed by washing of the colon that apparently there was a constant excretion of calcium by the colon, averaging about 0.8 mg., for the 3 hours.

Pouches (Thiry-Vella) of the upper jejunum and the lower ileum about 18 inches long were made; and pouches of the entire colon were made. Only dogs were used. These pouches were washed out at various intervals with distilled water, 0.1% HCl and 0.1% NaHCO₃, the amount of calcium in the washings being determined by the permanganate method.

It was found that daily washings with distilled water of the loop, or pouch, of the upper jejunum, yielded from 0.32 to 1.2 mg. of calcium; that daily washings of the pouch of the lower ileum yielded from 2.0 to 8.5 mg.; and that daily washings of the entire colon yielded from 1.8 to 15.0 mg. of calcium. Daily washings with the weak acid and alkaline solutions did not increase the yield. Washing out the lower ileum or colon at one hour intervals in succession for 6 or 8 hours markedly increased the yield, the yield of the lower ileum being from 24.0 to 30.0 mg., and of the colon from 17.6 to 55.4 mg., for 8 hours. Experiments are under way to determine the effect of bile, feces and mechanical distension on calcium elimination by the intestine.