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.