Relationship between endogenous concentrations of vasoactive substances and measures of peripheral vasodilator function in patients with coronary artery disease

P>The aim of the present study was to determine the relationship between plasma concentrations of nitrite/nitrate (NOx) and endothelin (ET)-1 and non-invasive measures of peripheral vasodilator function in patients with coronary artery disease (CAD). Twenty-two patients with angiographic CAD underwent non-invasive measurement of peripheral vasodilator function in the brachial conduit artery (flow-mediated dilation (FMD) testing via ultrasound) and in the forearm resistance arteries (via venous occlusion plethysmography) during reactive hyperaemia after 5 min ischaemia. In addition, plasma NOx and ET-1 concentrations were determined. The plasma concentration of NOx was related to the peak brachial FMD response when expressed as either the relative (%) or absolute (mm) change in diameter (r = 0.73, P < 0.001; and r = 0.64, P < 0.01, respectively). Moreover, plasma concentrations of NOx demonstrated a relationship with forearm vasodilation estimated by total forearm blood flow following 5 min ischaemia (r = 0.63, P < 0.01) and the flow debt repayment of the forearm (r = 0.54, P < 0.01). Finally, ET-1 concentrations were inversely related to FMD% (r = -0.45, P < 0.05). The findings of the present study demonstrate a relationship between the plasma concentrations of NOx and measures of vascular reactivity in conduit and resistance arteries in patients with CAD. Therefore, measurement of plasma NOx may serve as a reliable marker for peripheral vasodilator dysfunction in patients with CAD.