FIGURE 2.

Allopurinol (Allo; 100 μm) does not affect HbNO yield detected by EPR. EPR for experiments conducted with blood drawn from normotensive (A, C, and E) and hypertensive volunteers (B, D, and F). A, representative EPR spectra for samples with allopurinol (red) or vehicle (blue) collected from mixtures at 5 (dashed) and 30 min (solid) and from supernatants (SPT) at 50 min (dotted) from normotensive volunteers at pH 6.5 and 37 °C. B, representative EPR spectra for samples using RBCs from hypertensive volunteers at pH 7.4 and room temperature. C, average HbNO concentrations in RBCs from normotensive volunteers at pH 6.5 and 37 °C (n = 3). No significant differences were found for HbNO formed at 5 min (p = 0.8) and 30 min (p = 0.3) in mixtures and 50 min in supernatants (SPT; p = 0.2). D, average HbNO concentrations from experiments when RBCs were drawn from hypertensive volunteers at pH 7.4 and room temperature (n = 6). No significant difference was found for HbNO formed at 15 min (p = 0.4) and 30 min (p = 0.7) in mixtures and 50 min in supernatants (p = 0.5). E, upon the addition of exogenous XOR (10 μm), the addition of allopurinol reduced HbNO formation measured at 30 min after nitrite addition at pH 6.5 and 37 °C using red blood cells from normotensive individuals (p = 0.03, n = 3). No effect of allopurinol was observed at 5 min after nitrite addition in the mixture at 5 min (p = 0.8) or in the supernatants at 50 min (p = 0.6). *, versus −All, p = 0.03, n = 3. F, HbNO concentrations from experiments conducted using red blood cells from hypertensive volunteers with the addition of NADH at pH 7.4 and 37 °C. No significant difference was found between the amounts of HbNO formed in the mixture in the presence or absence of allopurinol (p > 0.6).