Role of nitric oxide in haemodialysis hypotension.

To investigate the possible involvement of nitric oxide (NO) in haemodialysis hypotension, we measured plasma concentrations of nitrate anion (NO3-), a metabolite of NO, in 114 patients undergoing maintenance haemodialysis. Mean plasma NO3- concentrations before dialysis were greater in subjects with lower blood pressure (155 +/- 16 micromol L-1) than in those with middle (117 +/- 8 micromol L-1) or higher blood pressure (105 +/- 12 micromol L-1) before dialysis. Further, mean plasma NO3- concentrations before dialysis were greater in subjects with lower blood pressure (186 +/- 13 micromol L-1) than in those with middle (112 +/- 7 micromol L-1) or higher blood pressure (64 +/- 11 micromol L-1) after dialysis. Plasma NO3- concentrations before dialysis were inversely correlated with mean blood pressure before dialysis (r=0.318, P=0.0006), and showed a strong inverse correlation with mean blood pressure after dialysis (r=0.608, P=0.0001). In the selected participants who had equal range of mean blood pressure before dialysis, mean plasma NO3- concentrations were greater in subjects with severe hypotension during dialysis (180 +/- 14 micromol L-1) than in those with mild hypotension (99 +/- 11 micromol L-1) or without hypotension (53 +/- 12 micromol L-1); plasma NO3- concentrations before dialysis were inversely correlated with changes in mean blood pressure during dialysis and mean blood pressure after dialysis. Results indicate that enhanced NO production may be involved in acute hypotension during dialysis, and suggest the possible involvement of NO in the pathogenesis of chronic hypotension associated with maintenance haemodialysis.