Nitrosylated Hemoglobin Levels in Human Venous Erythrocytes Correlate with Vascular Endothelial Function Measured by Digital Reactive HyperemiaReportar como inadecuado




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Impaired nitric oxide NO–dependent endothelial function is associated with the development of cardiovascular diseases. We hypothesized that erythrocyte levels of nitrosylated hemoglobin HbNO-heme may reflect vascular endothelial function in vivo. We developed a modified subtraction method using Electron Paramagnetic Resonance EPR spectroscopy to identify the 5-coordinate α-HbNO HbNO concentration in human erythrocytes and examined its correlation with endothelial function assessed by peripheral arterial tonometry PAT. Changes in digital pulse amplitude were measured by PAT during reactive hyperemia following brachial arterial occlusion in a group of healthy volunteers 50 subjects. Erythrocyte HbNO levels were measured at baseline and at the peak of hyperemia. We digitally subtracted an individual model EPR signal of erythrocyte free radicals from the whole EPR spectrum to unmask and quantitate the HbNO EPR signals.

Results

Mean erythrocyte HbNO concentration at baseline was 219+-−12 nmol-L n = 50. HbNO levels and reactive hyperemia RH indexes were higher in female free of contraceptive pills than male subjects. We observed a dynamic increase of HbNO levels in erythrocytes isolated at 1–2 min of post-occlusion hyperemia 120+-−8% of basal levels; post-occlusion HbNO levels were correlated with basal levels. Both basal and post-occlusion HbNO levels were significantly correlated with reactive hyperemia RH indexes r = 0.58; P<0.0001 for basal HbNO.

Conclusion

The study demonstrates quantitative measurements of 5-coordinate α-HbNO in human venous erythrocytes, its dynamic physiologic regulation and correlation with endothelial function measured by tonometry during hyperemia. This opens the way to further understanding of in vivo determinants of NO bioavailability in human circulation.



Autor: Irina I. Lobysheva , Pauline Biller, Bernard Gallez, Christophe Beauloye, Jean-Luc Balligand

Fuente: http://plos.srce.hr/



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