Gastrointestinal Absorption of Mg 28 in Rabbits. ∗

Abstract

Summary

Three groups of normal rabbits were starved for 17 to 48 hours prior to feeding of a dilute solution of MgSO₄. Mean urinary excretion of radioactivity in 48 hours in the 3 groups ranged between 10 and 12.5%. The high concentration of radioactivity detected in the midabdomen by external survey was traced to fecal content of caecum and colon. Fecal excretion was increased by resumption of feeding after exhibition of Mg²⁸, and concentration of radioactivity over the midabdomen decreased. These results suggest that poor gastrointestinal absorption of magnesium accounts for its low renal excretion. Absorption does not appear to occur from the large intestine.