Metabolic Studies with Radiobismuth: I. Retention and Distribution of${}^{206}{\rm Bi}$ in the Normal Rat

The retention of tracer doses of bismuth citrate in mature female rats indicated that there were three compartments which cleared exponentially. Two of these compartments were renal and accounted for 30% and 44% of the administered dose. The biological half-times of bismuth in these compartments were less than 30 min and 13 hr, respectively. The nonrenal compartment accounted for the remainder of the dose and its retention half-time was 122 hr. The major site of bismuth accumulation was in the kidney. Autoradiographs showed${}^{206}{\rm Bi}$ to be localized in the renal cortex. The kidney is shown to secrete${}^{206}{\rm Bi}$ into the urine and the renal extraction ratio is in excess of 0.92 for bismuth citrate. Whole-body scans at 24 hr do not reveal any other areas of concentration and demonstrate the applicability of this radionuclide as an imaging agent with conventional equipment.