Biology ETDs

Publication Date

5-19-1969

Abstract

These investigations were designed to assess the alterations in tissue distribution and excretion of inhaled radioyttrium in rats as a function of various concentrations of stable yttrium. One experiment utilized 91Y and three experiments utilized 88Y as the radioactive isotope. Stable yttrium was added to achieve various ratios of radioactive to non-radioactive yttrium in the inhaled particles. In experiment 1, Sprague-Dawley female rats were exposed by inhalation of aerosolized carrier-free 91Y and by inhalation of aero­solized 89Y labeled with 91Y. Other rats were injected intravenously with carrier-free 91Y (ionic) or with various concentrations of 89YCl3 labeled with 91Y. Daily whole-body counts were made and certain organs were removed for radiochemical analysis or direct radioactivity measurements when the rats were sacrificed 21 days after exposure. Additional studies were carried out with 88Y as the radioisotope. Experiment 2 consisted of 24 rats inhaling carrier-free 88Y, experiment 3 consisted of 25 rats inhaling particles with 89Y added for an 89Y; 88Y ratio of 5.85 x 104 and experiment 4 consisted of two groups of 5 rats each, inhaling particles with 89Y concentration equivalent to 89Y/88Y ratios of 5.45 x 104 and 2.18 x 105. Five rats from each exposure regime were placed in metabolism cages and the excreta were collected daily for radioanalysis. Whole-body counts were made on all rats, initially daily, then every other day until the time of sacrifice. The rats were dissected and bone, liver, lung, kidneys, spleen, adrenal gland and gastrointestinal tract were removed and counted. Significance tests were done at the 90% confidence level to detect differences in the whole-body retention, excretion and organ distribution of 88Y when inhaled carrier-free and when inhaled with stable yttrium. The observations significant at the 90% confidence level were: 1) there was less radioyttrium translocated from the lungs at all carrier ratios inhaled when compared to carrier-free radioyttrium, 2) at the maximum carrier 88Y/89Y ratio of 2.18 x 105, there was at least 30% more radioyttrium in the lungs at 32 days post-exposure than in the lungs of the carrier-free animals, 3) at the maximum carrier ratio there was at least 28% less radioyttrium in the skeleton at 32 days post-exposure than in the skeleton of the carrier-free animals, 4) there was no increase in radioyttrium concentration in the reticuloendothelial system, other than the lungs, as was observed in intravenous injection studies under the influence of high carrier concentrations. In addition, the following trends in agreement with the above conclusion were observed: high levels of inhaled stable yttrium labeled with radioyttrium tend to increase the retention of radioyttrium in the lung in proportion to the increase in carrier level, the mechanism of yttrium translocation from the lung appears to have several components in addition to or instead of atom availability for complex formation, and high carrier levels of inhaled yttrium possibly tend to increase the rate of fecal excretion of radioyttrium.

Project Sponsors

Contract AT(29-2)-1013 with the United States Atomic Energy Commission

Language

English

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Gordon Verle Johnson

Second Committee Member

Marvin LeRoy Riedesel

Third Committee Member

Martin William Fleck

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