The effects of castration and of the four weeks' administration of estradiol or testosterone on the blood circulation in the tibia and the kidney (expressed as the 85Sr-microsphere uptake values, which are not influenced by simultaneous changes in cardiac output) were studied in four experiments on a total of 147 rats (68 females, 79 males), relative weights being noted at the same time. 85Sr-microsphere uptake in the tibia rose markedly after castration in both males and females, fell after estradiol benzoate in intact females and intact and orchidectomized males and also fell after testosterone in intact and oophorectomized females and orchidectomized males. 85Sr-microsphere uptake in the kidney rose after castration only in males in experiments B; it fell after estradiol in orchidectomized males and fell after testosterone in intact females and males and in orchidectomized males. Relative tibial weight fell in castrated females, but in castrated males only in experiment D; after estradiol it rose only in males (intact and orchidectomized) and rose after testosterone in intact and oophorectomized females and orchidectomized males. Relative kidney weight fell after castration in both males and females, rose after estradiol in intact females and intact and orchidectomized males and rose after testosterone in intact and castrated males and females. In all four experiments there was a demonstrable statistically significant correlation between the 85Sr-microsphere uptake values in the tibia and the kidney. The relative weights displayed a similar correlation.(ABSTRACT TRUNCATED AT 250 WORDS)

Laboratory for Endocrinology and Metabolism 1st Medical Faculty Charles University Prague Czech Republic