Effect of lethal x-irradiation on urinary cortisol and 2-alpha- and 6-beta-hydroxycortisol excretion patterns and production rates in guinea pigs.

Abstract

The effect of fatal whole body X-irradiation (1000 r) on the urinary excretion of corticosteroids was studied in 2 guinea pig strains distinguished by high and low urinary hydroxylated cortisol derivatives (“high” and “low” producers). Following X-irradiation, there was a progressive drop in the urine output in the 2 strains. During radiation sickness, the high producers exhibited a significantly higher urinary excretion of polar corticosteroids such as 2α- and 6β-hydroxycortisol as compared to sham-irradiated animals. This resulted in an “inverted” excretion pattern with the polar corticosteroids becoming the dominant characteristic. The pattern changes were less apparent in the low producers because of their limited ability to form these compounds. Production rates of cortisol, 2α- and 6α-hydroxycortisol were determined in high producers from the cumulative specific activities of the urinary steroids following tracer injections. During the 24 hr which followed irradiation and 4 days thereafter when the animals showed signs of radiation sickness, there was a statically significant increase in the production rates of the 3 steroids studied which was 2−, 2− and 3-fold higher, respectively, over that found in sham-irradiated animals. The in vivo conversion of cortisol to 2α-hydroxycortisol and 6β-hydroxycortisol was not significantly affected by irradiation. (Endocrinology80: 947, 1967)