Vaskulárna medicína 2/2011

Expression of nitric oxide synthase isoforms in varicose vein wall

Introduction. There are conflicting findings in literature about structural changes of the primary varicose vein walls. Nitric oxide – a potent vazodilatátor – is synthesized by nitric oxide synthase (NOS). There are three known isoforms of NOS: nNOS (neuronal NOS), iNOS (inducible NOS), eNOS (endothelial NOS). Material and methods. Samples of varicose and control (healthy) veins were processed by standard light microscopy method and immunohistochemic technique using rabbit polyclonal antibodies against all three NOS isoforms: iNOS, eNOS and nNOS. Antibodies expression was evaluated semi quantitatively and proved morphometrically by 2D image analysis. Total area of NOS isoforms expressions was determined by color analysis and color digital subtraction. Results. We observed discontinuous and significantly lower expression of all three NOS isoforms in tunica media of varicose veins compared with control group, where the expression of all three NOS isoforms was continuous. For the statistical analysis was used unpaired t-test. Discussion and conclusion. Our results suppose lower NO levels in varicose vein wall, deducing that varicose vasodilatation is due to other mechanism, although the stage of chronic venous disease of varicose vein samples was undetermined. Our results are in contradiction with previously published results of Howlader and Abd-El-Aleem, who observed raised total NO levels in patients with severe stages of chronic venous disease.

Keywords: varicose veins, nitric oxide (NO), nitric oxide synthase (NOS)