The use of a novel reagent, Cu-FL, for determination of NO synthesis stimulated by the medicinal leech salivary cell secretion in human endothelial cell (HUVEC) and rat cardiomyocyte cultures

Abstract

Using a novel NO-specific reagent, the complex of Cu2+ with a fluorescein derivative (Cu-FL), stimulation of NO production by the medicinal leech salivary cell secretion (SCS) has been demonstrated for the first time in cultures of human endothelial cells (HUVEC) and rat cardiomyocytes (RCM). NO was detected in the cells by fluorescent electronic microscopy and determined quantitatively in the cells and in the culture fluid by the fluorescence method. SCSstimulated NO synthesis in HUVEC but not in RCM cells was accompanied by NO release into the intercellular space thus determining its subsequent distribution. Localization of intracellular NO synthesis centers is presented and it is shown that the increase in NO levels during the SCS action on HUVEC and RCM is associated with the increase in the activity of eNOS/nNOS, but not iNOS. In the endothelial cells SCS-activated nitrosylation processes, estimated by the increase of nitrite-ion content in the culture medium. It is therefore important to use Cu-FL, rather than Griss-reagent, during the first hour of analysis of NO synthesis. It is possible that the NO-depended mechanism of the SCS action on endothelial cells may be a factor responsible for the positive effect of SCS during hirudotheraphy.