Iefremova U. The properties of arginase and NO-synthase of peripheral blood lymphocytes in rheumatic diseases.

The dissertation is devoted to the research of NO-synthase/arginase system of blood lymphocytes of patients with rheumatoid arthritis and ankylosing spondylitis. The significant increase in arginase activity, an imbalance of constitutive (endothelial) and inducible NO-synthase of blood lymphocytes of patients with rheumatic disorders in comparison with practically healthy persons has been shown. It has been shown that in peripheral blood lymphocytes of patients with rheumatoid arthritis and ankylosing spondylitis the accumulation of urea in arginase reaction is faster and more intensive. It has been found that in conditions of rheumatic pathology the increase of arginase activity in immunocompetent cells is related to the increase of maximum reaction rate. The maximum speed of L-arginine hydrolysis (determined by [Mn2+]) in peripheral blood lymphocytes in patients with rheumatic pathology is greater in comparison to healthy persons. Affinity constant to L-arginine in peripheral blood lymphocytes for all the studied groups is not significantly different. It has been established that inhibition of eNO-synthase occurs by reducing the speed of the enzyme reaction. NO production in lymphocytes of patients with rheumatic diseases is mainly realized by iNO-synthase, whereas under normal physiological conditions endothelial isoform of the enzyme is being involved. The initial rate of NADРH(Н+) oxidation by eNO-synthase in patients with rheumatic pathology is lower than in practically healthy persons.