Purpose: To examine the effects of intermittent hypoxic breathing at rest (IHR) or during exercise (IHT) on blood pressure and nitric oxide metabolites (NOx) and hypoxia-inducible factor-1 alpha levels (HIF-1α) over a 6-week period.
Methods: 47 hypertensive patients were randomly allocated to three groups: hypertensive control (CON: n = 17; IHR: n = 15 and IHT: n = 15. The CON received no intervention; whereas, IH groups received eight events of hypoxia (FIO2 0.14), and normoxia (FIO2 0.21), 24-min hypoxia and 24-min normoxia, for 6 weeks. The baseline data were collected 2 days before the intervention; while, the post-test data were collected at days 2 and 28 after the 6-week intervention.
Results: We observed a significant decrease of the SBP in both IH groups: IHR (- 12.0 ± 8.0 mmHg, p = 0.004 and - 9.9 ± 8.8 mmHg, p = 0.028, mean ± 95% CI) and IHT (- 13.0 ± 7.8 mmHg, p = 0.002 and - 10.0 ± 8.4 mmHg, p = 0.016) at days 2 and 28 post-intervention, respectively. Compared to CON, IHR and IHT had increased of NOx (IHR; 8.5 ± 7.6 μmol/L, p = 0.031 and IHT; 20.0 ± 9.1 μmol/L, p < 0.001) and HIF-1α (IHR; 170.0 ± 100.0 pg/mL, p = 0.002 and IHT; 340.5 ± 160.0 pg/mL, p < 0.001). At 2 days post-intervention, NOx and HIF-1α were negatively correlated with SBP in IHT.
Conclusion: IH programs may act as an alternative therapeutic strategy for hypertension patients probably through elevation of NOx and HIF-1α production.
Keywords: Exercise; Hypoxicator; Malondialdehyde; Nitrite/nitrate; Simulated altitude; Six-minute walk test.