PLASMA 4-HYDROXY-2-NONENAL LEVELS DURING CARDIOPULMONARY BYPASS, AND THEIR RELATIONSHIP TO THE IRON-LOADING OF TRANSFERRIN

4-Hydroxy-2-nonenal (HNE) an aldehydic peroxidation product of n-6 fat ty acids, is formed predominantly in model systems when redox active t ransition metal ions, particularly iron, are present. During cardiopul monary bypass surgery blood is circulated and oxygenated extracorporea lly, and periods of tissue ischaemia-reoxygenation are introduced. Bot h events cause oxidative stress with the generation of reactive forms of oxygen leading to lipid peroxidation. During bypass iron is release d often saturating plasma transferrin, and resulting in the appearance of chelatable iron in the plasma. Because such forms of iron can prom ote HNE formation in vitro, we have studied 12 bypass patients, 5 of w hom had plasma iron-overload. Our results show a greater percentage in crease in HNE formation during bypass when the plasma transferrin is i ron-overloaded compared with matched controls not showing iron-overloa d.