There is difference of opinion among the authors on the possibility of using Rb 86 as an accurate tracer for the study of potassium metabolism. However, most of the investigations by these authors dealt mainly with normal subjects and therefore not directly applicabte in the pathologieal conditions which are commonplace in the clinical practice.
This is a report on the experimental studies about the metabolism of Rb 86 in comparison with potassium in the normal as well as some pathological conditions. This study is performed in the clinical research division of the National Institute of Radiological Sciences, Chiba, Japan.
As a first step of experiment, I have performed in vitro experiment to compare the active transport of K 42 and Rb 86 through the cellular membrane of R.B.C. There was marked difference in the uptake of both ions into the cells which is far more pronounced with the addition of tiny amount of glucoside which has known property of inhibiting active transport of potassium into the cells.
The glucoside acta far more strong on the potasaiom than the rubidium.
In the animal experiments using rabtits, we tried to alter the potassium metatolism by administering DOCA and X-Ray irradiation. This study revealed that when the rate of ancretion of potassium increases, the increased retention of Rb 86 resulted and vice versa. Same tendency was noted in the amount of both ion in the various organs of the animals which is slaughtered 4, 8, and 12 days after the irradiation.
There were two cases of volunteers among the inpatients of the hospital division of the institute. Both of them are with inoperable carcinoma of the uterus and receiving external and internal irradiation. Each patient was given one mc. of Rb 86 orally and followed with whole body countine and examination of blood, urine and saliva. One patient who was in the terminal stage of the disease died on 16th day and an autopsy was performed. Small pieces from each organ tissues were removed for counting of radioactivity and determination of potassium level in the tissue. There were fairly even distribution of Rb 86 relative to the K content of each organ tissue with the exceptien of liver and salivary gland.
As a result of this experiments, I was able to conclude that although there are manr similar features in the metabolic pattern of both ions, Rb 86 can not be regarded as an accurate and faithful tracer for the potassium metatolium particularly in the pathological conditions.
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