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Results for “PHOSPHORUS AND COMPOUNDS, RADIOACTIVE”

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PubMed1950

Mixing rate of phosphate between plasma and interstitial body fluid of cows.

Radiophosphate was injected into the left jugular vein of dairy cows. Blood samples were taken frequently from the right jugular vein during the first hour after injection. Between 20 minutes and 1 hour after injection, the decrease in plasma radioactivity could be formulated as a first order process, designated as "process 3," with a turnover time of 50 minutes. From 5 to 20 minutes after injection the decrease in plasma activity could be interpreted as the result of mixing plasma phosphate with another phosphate pool, designated as the second pool. The capacity of this second pool was derived as a constant in a kinetic equation, so chosen that the resulting mixing rates were independent of time. For two cows the capacity of the second pool was 5 and 8 times, respectively. the phosphate content of the plasma. This result led to the working hypothesis that the major part of the second pool was the phosphate in the interstitial tissue fluid. The turnover time of the plasma phosphate in the mixing process with the second pool amounted to an average of 14 minutes for 5 lactating cows, and an average of 21 minutes for 2 dry cows. This result was obtained under the assumption that the slow first order process 3 is parallel to the mixing process. The assumption that the slower first order process is in series with the mixing process reduces the resulting mixing time to about four-fifths of that reported above. The calculation of process 2 which deviates from first order may be applicable to numerous turnover processes in which both exchange pools have a limited capacity.

Animals↗
PubMed1950

Tissue culture studies; growth of tissue in vitro as related to the direct measurement of P32 uptake.

An improved procedure for measuring the uptake of tracer P(32) by tissues in culture is described. It consisted of counting the beta-emissions through a specially designed roller tube in which the culture medium could be effectively removed from the system without opening or damaging the cultures. In standard growth-promoting medium, the uptake was shown to be markedly greater than in Tyrode's solution. The uptake curve was found to be essentially parallel with the uptake of P(32) in desoxyribo- and ribonucleic acids when standard medium was used, and in desoxyrihonucleic acid when Tyrode's solution was used. This is interpreted to signify that the total uptake of tracer phosphorus approximates the growth in the culture. The value of uptake measurements as a frame of reference for comparison of various types of media and of metabolic studies is indicated.

In Vitro Techniques↗