Retention and subcellular distribution of 67Ga in normal organs

Using normal rats, retention values and subcellular distribution of 67Ga in each organ were investigated. At 10 min after administration of 67Ga-citrate the retention value of 67Ga in blood was 6.77% dose/g, and this value decreased with time. The values for skeletal muscle, lung, pancreas, adrenal, heart muscle, brain, small intestine, large intestine and spinal cord were the highest at 10 min after administration, and they decreased with time. Conversely, this value in bone increased until 10 days after injection. But in the liver, kidney, and stomach, these values increased with time after administration and were highest 24 h or 48 h after injection. After that, they decreased with time. The value in spleen reached a plateau 48 h after administration, and hardly varied for 10 days. From the results of subcellular fractionation, it was deduced that lysosome plays quite an important role in the concentration of 67Ga in small intestine, stomach, lung, kidney and pancreas; a lesser role in its concentration in heart muscle, and hardly any role in the 67Ga accumulation in skeletal muscle. In spleen, the contents in nuclear, mitochondrial, microsomal, and supernatant fractions all contributed to the accumulation of 67Ga.