Discrimination in Intestinal Absorption of Strontium and Calcium.

Summary Absorption of Sr85 and Ca45 was studied in the rat by the technic of in vivo intestinal perfusion. With no calcium added to the perfusion solution the percentage of Sr85 absorbed was about 0.3 that of Ca45. With increasing levels of calcium in the perfusion solution, the percentage of Sr85 and Ca45 absorbed decreased; however, the ratio of percentage absorption of Sr85 to Ca45 increased, reaching a value of about 0.6 in 25 mM calcium solution. There was no evidence of discrimination in the reverse movement of Sr85 and Ca45 from blood to intestine. The discrimination which occurs in the absorption process would appear to be a dominant factor in determining over-all strontium calcium relationships.