Adrenal Influences on Distribution of Injected Colloidal Thorium

¹ From the Department of Biology, Graduate School of Arts and Science, New York University, New York City

A chemical analysis was made of the influence of adrenalectomy upon the distribution of intravenously administered colloidal thorium dioxide (thorotrast) in spleen, liver, lymph nodes, lung, blood and urine of the adult rat. Adrenalectomy resulted in a decrease in the uptake of thorium by the spleen; this occurred as early as 2 hours and was maintained for at least 48 hours after its administration. The blood levels decreased quickly; only slight amounts remained after 2 hours. No significant differences were noted in thorium concentration within the livers of normal and adrenalectomized rats at 2, 4, 8, 24 and 48 hours after its injection. The lungs and lymph nodes (at 2 hr.) of adrenalectomized rats accepted slightly greater amounts of the metal than similar organs in control rats. Thorium was excreted in urine in slight amounts; but adrenalectomy resulted in a slightly greater excretion of ThO₂/gm dried urine. Although the concentrating activity of spleen was much greater than the liver, the total amount of thorium deposited in the liver was larger. The quantities of thorium recovered from the normal rats were always greater than those from adrenalectomized animals, by a difference almost identical with that found between the spleens from normal and operated animals. The relatively large differences in thorium uptake by the spleens of normal and adrenalectomized animals cannot be accounted for by the differences in thorium deposition in other organs studied and by elimination in the urine. The discrepancy is probably explained on the basis of differential entry of thorium into tissues other than those examined in the present study.