Indexes of nitric oxide system in experimental antiphospholipid syndrome

Abstract

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the presence of antibo­dies to negatively charged membrane phospholipids (aPL). Endothelial dysfunction is one of the most dangerous­ APS manifestations followed by thrombosis, placental insufficiency and often foetal death due to circulatory disorders in placenta blood vessels. It is established that synthesis and bioavailability of nitric oxide (NO) in the endothelium are impaired at APS, but the role of NO system in pregnancy failure at this pathology remains ambiguous. The aim of this research was to estimate the indexes of the nitric oxide system in animals with an experimental antiphospholipid syndrome before pregnancy and on the 18th day of pregnancy, without­ treatment and under treatment with nitric oxide synthesis modulators (L-arginine and aminoguanidine). In the blood serum and liver of the BALB/c mice with experimental APS, the content of eNOS and iNOS– by ELISA and the level of NO2– and NO3– with the use of Gris reagent were determined before pregnancy and on the 18th day of pregnancy. The data obtained indicate the relative inefficient NO production by eNOS and NO hyperproduction by iNOS in the blood serum and liver of mice in the pathogenesis of experimental APS. Thus, in mice with APS before pregnancy and on the 18th day of the pregnancy, the eNOS content and NO2– level were decreased while the iNOS content and NO3– level were increased compared to the indexes in the control animal group. L-arginine administration to the animals with APS at the follow-up periods resulted in an increased eNOS content and NO2–, NO3– levels in blood serum and liver with the simultaneous decrease in iNOS content in the liver as compared to indexes in untreated mice with APS. The combined use of L-arginine and selective iNOS inhibitor aminoguanidine caused a significant increase in eNOS content and a decrease in iNOS content followed by normalization of NO2– and NO3– levels in blood and liver of mice with experimental APS before pregnancy and on the 18th day of pregnancy compared to untreated mice with APS.

Keywords

• aminoguanidine
• antiphospholipid syndrome
• enos
• inos
• l-arginine
• nitric oxide