Passage of 85 Sr and 47 Ca into the Gastrointestinal Tract in Rats during Feeding and Fasting

Abstract

The secretion of ${}^{85}{\rm Sr}$ and ${}^{47}{\rm Ca}$ from the vascular space into the intestine was determined in rats as a function of time during both feeding and fasting. ${}^{85}{\rm Sr}$ and ${}^{47}{\rm Ca}$ were injected intravenously, and the rats were sacrificed after 1/2, 1, 2, 4, and 24 hours. The gastrointestinal radioisotope content was measured in six separate segments. During feeding, slightly more ${}^{47}{\rm Ca}$ than ${}^{85}{\rm Sr}$ , 5.1% vs 4.6% of the dose, respectively, was present at 1/2 hour in the gastrointestinal tract. At 4 hours the ${}^{85}{\rm Sr}$ in the intestine rose to 7.0%, while ${}^{47}{\rm Ca}$ had increased only very slightly. Between 4 and 24 hours the excretion of both isotopes via the intestine increased, but the increase in ${}^{85}{\rm Sr}$ excretion was greater than tha...