The absorption of calcium, strontium, barium and radium from the gastrointestinal tract of the rat

Abstract

Absorption of calcium, strontium, barium and radium from the gastrointestinal tract of the rat has been studied by means of double radioactive-tracer techniques. At 14-18 days of age there is almost complete absorption of calcium and strontium and about 80% of barium and radium is absorbed. For animals 6-8-weeks old absorption of calcium has decreased to about 60%, strontium to 25%, barium to 7% and radium to 11%. In animals at 60[long dash]70 weeks of age the absorption of all the elements except barium is decreased to between one-third and one-half of these levels. Deprivation of food before administration markedly increases the absorption of barium and radium and slightly reduces calcium absorption. Administration of the elements in cow''s milk significantly enhances the absorption of calcium and, more particularly, strontium in 6[long dash]8 week-old rats. The absorption of barium and radium is not affected and the effect is not observed in old animals. The results for the absorption of barium and radium show a closer similarity to each other than to the results for strontium and calcium.