Detoxication and Excretion of Radioactive Strontium. IV. Effect of Sodium Calcium Citrate and the Mode of Action of Citrate.

After the injection of radioactive strontium, a mixture of trisodium citrate and monosodium monocalcium citrate was injected into rats and the effect of monosodijm monocalcium citrate injection in accelerating the excretion of radiostrontium was compared with the effect of the injection of trisodium citrate only. Greatly enhanced excretion of radiostrontium into urine was found in the rats treated with sodium calcium citrate, without any symptom of hypocalcemia. When citrate was injected into rats in the form of either trisodium salt or sodium calcium salt, citrate level in blood plasma was greatly elevated and nearly one-half of injected citrate was found in the urine within six hours. Mechanism of the action of citrate on the excretion of radioactive strontium is discussed and attributed to its chelating ability.