Comparative kinetics of 45Ca and 89Sr in chronic uremic syndrome in the rat

In rats a chronic uremic syndrome was induced by 5/6 resection and subsequent irradiation of the kidneys. After 5 weeks 45Ca and 89Sr were injected simultaneously, and the different metabolic handling of the two elements was determined applying an open two-compartment model of Calcium kinetics. The uremic animals were compared with two groups of rats which were pairfed, and fed ad libitum, respectively. Besides an elevenfold faster urinary excretion when calculated with Sr, and which was reduced to about one half in the uremic rats, a significant discrimination by bone in favour of Ca was found, with a rather stable factor of 1.2 in the three groups. This is considered to evidence that urinary excretion and bon uptake of Sr are independent processes.