Negative NO3 center dot difference in human coronary circulation with severe atherosclerotic stenosis

To examine whether or not the levels of NOx (nitrite; NO3- and nitrate; NO, ) in coronary circulating blood reflect endothelial dysfunction due to coro nary atherosclerosis, NOx levels in plasma obtained from ostium of:left cor onary artery and coronary sinus of patients who complained of chest pain we re evaluated in relation to their coronary angiographic findings. Prior to the study, a HPLC-Griess system for NOx measurement Was critically evaluate d. This system has a detection limit of 0.1 mu M of NO; and NO, by 10 yl of loading and was able to distinguish a difference of 0.1-0.2 mu M of these substances. Heparin (1U/10 mu l) did not affect the detective and discrimin ative abilities. NO,' difference, calculated from sino-arterial difference of NO,, was almost zero (-0.2 +/- 0.2 mu M) in patients with either normal coronary arteries or mild organic coronary stenosis (less than or equal to 20% narrowing), while a significant negative value(-5.9 +/- 1.7 mu M) was o btained from patients with significant stenosis (greater than or equal to 7 0% narrowing) in the left coronary arteries. These results demonstrate reli able ability on the HPLC-Griess system in evaluating NO2- and NO, in biolog ical samples, and that the negative NO, difference through coronary circula tion may reflect endothelial dysfunction in the patients with coronary athe rosclerosis with severe organic stenosis.