ISOCRATIC HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF PLASMA ADENOSINE

Due to manifold physiological and cardioprotective actions of adenosin e, the demand for a simple but accurate method to determine its concen tration in plasma is increasing. The aim of this study was firstly to develop a simple isocratic method instead of the gradient elution or p eak-shifting techniques used earlier and secondly to check conflicting data on the composition of ''stop-solution'', added to the sample in order to prevent changes in adenosine concentration. Isocratic elution improved signal to noise ratio and concentrations of 100 mu mol L(-1) dipyridamole and 2.5 mu mol L(-1) erythro-9(2-hydroxy-3-nonyl)adenine in the blood sample effectively prevented both adenosine formation an d degradation, even without the use of a 5'-ecto-nucleotidase inhibito r. Lowering the concentration of dipyridamole to 25 mu mol L(-1) cause d more than a tenfold increase of adenosine concentration in two out o f five cases and even 100 mu mol L(-1) dipyridamole alone is not suffi cient to inhibit adenosine deaminase in blood samples.