Measurement of exchangeable nickel in the rat

⁶³Ni Cl₂ was injected intravenously into rats which were exsanguinated at multiple time points following injection. Tissues were removed and analyzed for radionickel concentration. Tissue exchangeable pools were directly estimated and compartmental analysis performed by computer evaluation of the percent isotopic retention versus time. Kidney was found to have the largest rapidly exchangeable tissue pool with an approximate value of 10 ng/gm (wet wt.) during the first sixteen hours of study. Compartmental analysis was most compatible with two intracellular compartments in kidney, liver, lung and spleen. Bone had best fit with only one compartment. The rapid compartment in most tissues had half time of several hours, while the slower compartment had a half time of several days. The authors feel these data are consonant with the existance of a homeostatic mechanism operant for nickel.