Biology ETDs

Publication Date

5-30-1968

Abstract

Effects of diet on 137Cs retention and distribution in the rat were examined. After a 7-day period, retention of an intraperitoneal dose of 137Cs was higher than control values for rats fed semistarvation, high carbohydrate, high protein, and high fat diets. Relative distribution of 137Cs among tissues .was examined considering changes in tissue composition due to diet variation. The primary effect of diet on cesium metabolism was a modification of cesium excretion via urine and feces. There appeared to be a direct relationship between mass of fecal material and the amount of 137Cs excreted in feces. Diet variation changed the composition and amount of material in the intestinal lumen to which cesium could be adsorbed for subsequent excretion in feces. On the other hand, cesium excretion via urine seemed to be less dependent on the amount of urine produced; the amounts of urea, fatty acids, amino acids, or glucose in the blood may be important factors in renal 137Cs excretion. Rats fed a high protein diet produced approximately twice the volume of urine as control animals, yet urinary excretion of 137Cs in both groups was similar. Excretion of 137Cs in urine of animals fed high carbohydrate, semistarvation, and high fat diets was apparently proportional to urine volume. It seems unlikely that retention of cesium can be decreased in rats by enriching diets with carbohydrate, protein, or fat, even if diuresis can be induced in conjunction with the enriched diets. The decrease in feces production which accompanies enriched diets obscures any advantages pained by using the enriched diets. Varying the primary intracellular nutrients by feeding rats high carbohydrate, high protein, or high fat diets resulted in an increased or decreased affinity of some cells for cesium. High protein diets may facilitate 137Cs accumulation in liver; high carbohydrate and high fat diets resulted in a low liver TRI, indicating a lack of liver accumulation of 137Cs. The effect may have been due to changes in ionization of intracellular proteins, a shift in the relative amounts of stored nutrients, or a change in the relative amount of connective tissue present. Tissue retention index values are subject to change by factors such as tissue mass change, redistribution of the isotope among tissues, and lack of displacement of strongly bound ions. Skeletal muscle is a tissue where all three of these factors can be observed. Cesium ions are apparently strongly held in muscle tissue, possibly to contractile protein. Loss of contractile protein during muscle atrophy increases the relative proportion of connective tissue (to which cesium ions are not strongly attracted) and forces redistribution of the ions.

Project Sponsors

Atomic Energy Commission Research Contract AT(29-2)-1629, National Defense Fellowship (Title IV) number 67-07102

Language

English

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Marvin LeRoy Riedesel

Second Committee Member

Clifford Smeed Crawford

Third Committee Member

James Samuel Booth

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