Nitric oxide released from zwitterionic polyamine/NO adducts inhibits Cu 2+-induced low density lipoprotein oxidation

Abstract

The effects of nitrix oxide (NO) released from zwitterionic polyamine/NO adducts on Cu 2+-induced low density lipoprotein (LDL) oxidation were studied. When each of the two kinds of NO releasing zwitterionic polyamine/NO adducts (NOC5 and NOC7) was incubated at 5 μM with isolated human LDL (0.25 mg/ml) and Cu 2+, the formation of thiobarbituric acid reactive substances (TBARS) was inhibited. The duration of inhibition by NOC7 (20 min) and NOC5 (100 min) corresponded to the NO generation lives of respective zwitterionic polyamine/NO adducts. The duration of inhibition was dependent on the amount of NOC5 added (2.5–20 μM). Repeated additions of 5 μM NOC5 at 100 min intervals worked as inhibitor in the same manner. NOC5 broke to inhibit at any process of the Cu 2+-induced LDL oxidation reaction. Fragmentation of apolipoprotein B derived from Cu 2+-induced LDL oxidation was also prevented by the addition of NOC5. These results clearly indicate that NO inhibits the oxidative modification of LDL induced by Cu 2+. NO releasing zwitterionic polyamine/NO adducts are good reagents for NO studies.