Abstract: In order to explore the mechanism of trans C18:1-induced endotheliocyte damage by NOS-NO system, the viability of human umbilical vein endothelial cells (HUVECs) subjected to trans C18:1 treatments at the concentrations of 50, 100, 200μmol/L and 400μmol/L for 24 or 48 h was determined by MTT assay. Meanwhile, the content of NO and the activity of NOS in HUVECs treated with trans C18:1 at the dose of 200μmol/L for 24 h were also determined using a commercial kit. Moreover, the viability of HUVECs subjected to treatments of trans C18:1 coupled with nitric oxide synthase inhibitor L-arginine methyl nitrite (LNAME) and/or nitric oxide donor (SNP) were also determined. The results indicated that trans C18:1 could decrease the viability of HUVECs in a dose- and time-dependent manner. The viability of HUVECs could be decreased by the combinatorial treatment of LNAME and trans C18:1 but increased by the combinatorial treatment of SNP and trans C18:1. trans C18:1 treatment could induce the secretion of NO and significantly decrease the activity of eNOS, but had no obvious effect on the activity of iNOS in HUVECs. Therefore, trans C18:1 treatment can reduce the secretion of NO through inhibiting eNOS activity, which suggests that the involvement of NOS-NO system is one of the important mechanisms of trans C18:1-induced HUVEC damage.

Key words: trans C18:1, human umbilical vein endothelial cell (HUVEC), NOS, NO, damage