Cardiovascular mortality in dialysis patients remains a serious problem. It is 10 to 20 times higher than in the general population. No molecular mechanism has been proven to explain this increased mortality, although nitric oxide (NO) has been implicated. The objective of our study was to determine the extent of removal of plasma and salivary NO congeners nitrite and nitrate by hemodialysis, as this might disrupt physiological NO bioactivity and help explain the health disparity in dialysis patients. Blood and saliva were collected at baseline from patients on dialysis and as it exited the dialysis unit. Blood and saliva were again collected after 4-5 hours of dialysis. In the 27 patients on dialysis, baseline plasma nitrite and nitrate by HPLC were 0.21±0.03µM and 67.25±14.68µM, respectively. Blood immediately upon exit from the dialysis unit had 57% less nitrite (0.09±0.03µM; P=0.0008) and 84% less nitrate (11.04µM; P=0.0003). After 4-5 hours of dialysis, new steady state plasma levels of nitrite and nitrate were significantly lower than baseline 0.09±0.01µM (P=0.0002) and 16.72±2.27µM (P=0.001), respectively. Dialysis also resulted in a significant reduction in salivary nitrite (232.58±75.65µM to 25.77±10.88µM; P=0.01) and nitrate (500.36+154.89µM to 95.08±24.64µM; P=0.01). Chronic and persistent depletion of plasma and salivary nitrite and nitrate likely reduces NO bioavailability and may explain in part the increased cardiovascular mortality in the dialysis patient.
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