A technique in which radioisotopes are used for the measurement of the rates of synthesis of compounds within living cells. A suspension of cells or organelles is exposed to a small quantity of an isotope for a brief period (seconds or minutes), hence the term ‘pulse’. This is achieved through the addition to the suspension of a much larger quantity of the stable (unlabelled) isotope of the same compound following the required period of exposure to the radioisotope. The effect of competition between the two isotopes is to reduce to a negligible level the further uptake of the latter. Measurement of the levels of activity in samples under various experimental conditions can yield useful information regarding the factors influencing the uptake and metabolism of compounds.
Subjects: Plant Sciences and Forestry — Ecology and Conservation.