IMPACT OF NITRIC-OXIDE ON BLOOD-PRESSURE IN HEMODIALYSIS-PATIENTS

Nitric oxide (NO) is a powerful vasoactive agent that contributes to t he regulation of blood pressure (BP). However, the role of NO in uremi c patients and during the course of hemodialysis is still debated. Blo od L-arginine concentrations and exhaled NO concentrations were measur ed in 22 healthy controls and in 22 hemodialysis patients before and a fter dialysis, On the basis of their BP response during hemodialysis, the patients were divided into three groups: 6 of the 22 patients pres ented with a decrease in BP during dialysis (group 1), eight presented with a stable BP (group 2), and eight with an increase in BP (group 3 ). The exhaled NO concentration was higher in dialysis patients than i n healthy controls (22.7 +/- 2.6 ppb in dialysis patients v 16.7 +/- 0 .9 ppb in controls, mean +/- SEM, P = 0.044). The predialysis and post dialysis exhaled NO concentrations were inversely correlated with the change in BP during hemodialysis (r = -0.47, P = 0.013). Patients with a decrease in BP (group 1) had the highest NO concentrations; patient s with an increase in BP (group 3) had the lowest values; and patients with a stable BP during the course of dialysis (group 2) had intermed iary values (trend test, P = 0.0291). In addition, both the exhaled NO concentration and the blood L-arginine concentration decreased during dialysis in all patients (P = 0.005 and P = 0.001, respectively). The se results provide several novel insights into NO metabolism and BP re gulation during hemodialysis: (1) maintenance hemodialysis is associat ed with a chronic increase in NO concentrations; (2) changes in BP dur ing hemodialysis are inversely correlated with exhaled NO concentratio ns, higher NO levels being associated with a decrease in BP and lower NO levels with an increase in BP during dialysis; (3) blood L-arginine levels decrease during hemodialysis, and this reduction may in turn i nfluence NO production. (C) 1997 by the National Kidney Foundation, In c.