Distribution and Excretion of Nickel-63 Administered Intravenously to Rats

Abstract

The distribution and excretion of ⁶³Ni administered intravenously was studied using 64 Sprague-Dawley female rats. Small quantities of tissues (50–75 mg) were acid-digested and the isotope was counted using a liquid scintillation system. The major portion (61%) of a single intravenous injection of ⁶³Ni was excreted via the urine within 72 hours, with a lesser amount appearing in the feces (5.9%). In addition, the ⁶³Ni activity in the whole blood and plasma had completely disappeared by 48 hours with no accumulation in the red blood cells. The relative distribution of the ⁶³Ni per gram of fresh tissue was as follows: kidney > adrenal > ovary > lung > heart > eye > thymus > pancreas > spleen > liver > epidermis > gastrointestinal tract > muscle > incisor > femur = brain > adipose. However, in all tissues analyzed the ⁶³Ni decreased rapidly, and after 72 hours only the kidney contained significant amounts of ⁶³Ni. The ⁶³Ni distribution was compared with the blood volume of specific tissues. Correlation coefficients were 0.79, 0.76, 0.82 and 0.68 for intervals of 15 minutes, 2 hours, 6 hours, and 16 hours, respectively, following intravenous injection of the isotope. These correlations were statistically significant and suggest that the distribution of the ⁶³Ni was directly dependent upon the relative blood volume of the specific tissues analyzed.