Philip S. Chen

COMPARISON OF THE PHYSICO-CHEMICAL AND PHYSIOLOGICAL BEHAVIOR OF NATURAL INULIN WITH ITS RADIOACTIVE DERIVATIVES

Summary In several in vitro systems it has been found that the C14 (inulin-C14OOH) and H3 (inulin-OCH3 3) labelled derivatives behave differently from ordinary inulin. Several lots passed faster than inulin through cellophane tubing in dialysis or centrifugal-pressure ultrafiltration. Size differences were also demonstrated by gel filtration through Sephadex G-50 column. Migration of inulin-C14OOH from inulin occurred in paper electrophoresis because of its anionic nature. Following a single i.v. injection to a dog, urine C14 specific activity was not higher than administered dose but fell with time, showing that the glomerular capillaries did not restrict filtration of inulin as compared with the smaller inulin-C14OOH. It is suggested that a more rapid rate of extrarenal removal of the radioactive inulin-C14OOH occurred.

Specific Activity of Inulin-C14OOH in Serum and Lymph of Nephrectomized Dog.∗

Summary Following intravenous injection of inulin-C14OOH and inulin into a nephrectomized dog, the thoracic duct lymph was considerably higher than serum in specific activity, falling gradually to serum values. The fractionation of the smaller inulin-C14OOH molecules in lymph formation was thus similar to that observed in ultrafiltration through cellophane membranes, but it was quantitatively of insufficient magnitude to effect an observable decrease in serum inulin specific activity. It is suggested that the decrease in urine specific activity previously reported for the intact dog was due to a quicker uptake of inulin-C14OOH than non-labelled inulin by renal tissue.

Distribution of vitamin D3-4-C14 in rachitic and vitamin D3 treated chicks.

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.