Dynamics of nitric oxide release in the cardiovascular system

The endothelium plays a critical role in maintaining vascular tone by releasing nitric oxide (NO). Endothelium derived NO diffuses to smooth muscles, triggering their re­laxation. The dynamic of NO production is a determining factor in signal trans- duction. The present studies were designed to elucidate dynamics of NO release from normal and dysfunctional endothelium. The nanosensors (diameter 100-300 nm) exhibiting a response time better than 100 us and detection limit of 1.0x10-9 mol L-1 were used for in vitro monitoring of NO release from single endothelial cells from the iliac artery of normotensive (WKY) rats, hypertensive (SHR) rats, and normal and cholesterolemic rabbits. Also, the dynamics and distribution of NO in left ventricular wall of rabbit heart were measured. The rate of NO release was much higher (1200 ± 50 nmol L-1 s-1) for WKY than for SHR (460 ± 10 nmol L-1 s-1). Also, the peak NO concentration was about three times higher for WKY than SHR. Similar decrease in the dynamics of NO release was observed for cholesterolemic rabbits. The dynamics of NO release changed dramatically along the wall of rabbit aorta, being highest (0.86 ± 0.12 ,umol L- 1) for the ascending aorta, and lowest for the iliac aorta (0.48 ± 0.15 ,Mmol L-1 ). The distribution of NO in the left ventricular wall of rabbit heart was not uniform and varied from 1.23 ± 0.20 ,umol L-1 (center) to 0.90 ± 0.15 ,umol L-1 (apex). Both, the maximal concentration and the dynamics of NO release can be useful diag­nostic tools in estimating the level of endothelial dysfunction and cardiovascular system efficiency.