Isocratic high-performance liquid chromatographic determination of plasma adenosine

Summary

Due to manifold physiological and cardioprotective actions of adenosine, the demand for a simple but accurate method to determine its concentration in plasma is increasing. The aim of this study was firstly to develop a simple isocratic method instead of the gradient elution or peak-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 μmol L⁻¹ dipyridamole and 2.5 μmol L⁻¹ erythro-9(2-hydroxy-3-nonyl)adenine in the blood sample effectively prevented both adenosine formation and degradation, even without the use of a 5′-ecto-nucleotidase inhibitor. Lowering the concentration of dipyridamole to 25 μmol L⁻¹ caused more than a tenfold increase of adenosine concentration in two out of five cases and even 100 μmol L⁻¹ dipyridamole alone is not sufficient to inhibit adenosine deaminase in blood samples.