[The detection of nitric oxide and NO-derivatives in the endothelial cells and tissues].

The correctly working endothelium produces suitable quantities of nitric oxide (NO) and other mediators, necessary for maintenance of homeostasis of cardiovascular system. Because of correlation between the availability of NO and the physiological state of the whole organism, monitoring the concentration of nitric oxide is essential for the better understanding of pathogenesis of many diseases. For this reason, there are intensive studies performed to develop new methods allowing the control of NO concentration in biological specimens. Thus, we should pay a special attention on the methods which make possible the measurement of the concentration of nitric oxide and reactive oxygen species (ROS). They can be based on analysis of adducts formed by ROS with different stable complexes, on measurement of the direct products of oxygenation, or on the reduction of radicals. Electron paramagnetic resonance (EPR) deserves special attention, as it allows for the direct measurement of free radical signals or for analysis of stable adducts of radicals with the spin traps. Other methods should be used, however, to confirm and extend the results of EPR examination.