Metabolic studies using Zn-65. 8. Variations of the relative distribution of Zn-65 in the guinea pig

Abstract

The study of Zn-65 distribution (60 /xc/kg in one intraperitoneal dose) was undertaken in certain organs of Guinea pigs within a period of 6 to 140 days.

Seven lots of Guinea pigs of not less than 6 animáis in each lot were injected with Zn-65, and kept for a period of 6, 15, 27, 45, 60, 80 and 140 days respectively. After the termination of each pe­riod, the animals were killed and the Zn-65 content was determined in the following groups of organs: carcass, skin and hair, encephalon, eyes, nails, teeth, liver, pancreas, spleen, stomach, intestine, kidneys and adrenals, male genital apparatus, lungs and the heart.

The results showed that 1) the carcass and specially the osseous system constituted the main sites of Zn-65 deposits, with a 58 % of the body burden. The accumulation remained practically constant within the 27 and 140 days period.

2) The skin and hair but specially the hair constituted the second centre of Zn- 65 accumulation.

3) The third site of Zn-65 deposit occured in the kidneys and the adrenals having and approximate value of 1.5 %.

4) The nails, allowing for its small mass, represents another site of deposition with and approximate valué of 0.35 %.

5) The thoracic and abdominal organs show a continued decrease in its contribution to the body burden, in such a manner that within the periods 6 and 140 days the valué of the stated propportion of 31 % is reduced by a tenth.

6) The teeth and encephalon, wich are very distinct parts, present very similar variations. With a period of increase until the 22nd days, when the Zn-65 content is 5.5 % and 0.5 % respectively, these values then decrease gradually to give values of 2.9 % and 0.27 % in the 140th day.