Distribution of Vitamin D 3 -4-C 14 in Rachitic and Vitamin D 3 Treated Chicks. ∗

Abstract

Summary

The distribution of vit. D₃-4-C¹⁴ in rachitic and vit. D₃-treated chicks was assessed following oral intubation into chicks fed rachitogenic diet alone (rachitic) or treated with 6 IU/day of vit. D₃. At 24 hours, the chicks were sacrificed and the radioactive material in each tissue was extracted from saponified tissue, then partitioned into a nonpolar fraction (iso-octane) containing primarily vit. D₃ and a polar fraction (67% methanol) containing only breakdown products. Radioactivity was assayed in the ANSitron liquid scintillation counter using automatic external standardization for correction of counting efficiency.

Radioactivity was widely distributed in all tissues of the chicks with high uptake, on a concentration basis, by intestinal tract, liver, kidneys, adrenal glands, spleen and gall bladder and in serum. Muscle and pancreas were low in localized uptake. However, bone, muscle and skin each quantitatively accounted for a greater percentage than liver.

From the relative proportion of activity in the polar partition phase (67% methanol) compared to that in the iso-octane partition phase, it can be inferred that the intestinal tract activity was mainly vit. D, in contrast to skin, spleen and gall bladder, muscle, and bone where considerable breakdown products were present.

The small intestines of the rachitic animals contained considerably more activity than corresponding tissue in the vit. D₃-treated chicks, whereas livers, ceca and large intestines contained less activity. Rachitic chicks excreted more activity than the vit. D-treated animals. Other tissues (muscle, bone, skin, adrenal glands) were quite similar in uptake in both groups.