Intermittent Hypoxia-hyperoxia Conditioning as a New Therapeutic Intervention to Reduce Hypertension (HyperIHHC)

The primary objective of this project is to examine the efficiency of intermittent hypoxia-hyperoxia conditioning (IHHC) protocol to improve vascular health and reduce blood pressure in hypertensive patients (stage 1). The result of the present study will investigate if IHHC could be a therapeutic treatment for hypertensive individuals. The investigation is designed with a placebo intervention (air ambient) and a control group (age-matched healthy participants). The interest of short cycles of intermittent hypoxia-hyperoxia is due to the triggering of the vasodilatory response in a greater extent compared to the pressor mechanisms since the exposure duration remains short. Therefore, it can be hypothesized that control and hypertensive groups achieving IHHC may exhibit a decreased blood pressure compared to the control and hypertensive groups achieving placebo intervention. The control group may show greater change than hypertensive due to higher vascular reserve.The secondary objective of the study is to understand the underlying mechanism of the beneficial effects of IHHC, especially the role of blood hemorheological changes. Based on available literature, it is know that hypoxia induce an increase in blood viscosity. One may hypothesize that with such a short hypoxic dose used during IHHC, only minor change in blood viscosity may occur. However, a slight rise in blood viscosity is known to stimulate NO synthase and then to produce more NO. Hence it could be one of the mechanisms involved in the early vasodilatory response to hypoxia. These findings are in line with the reported higher NO end-product metabolites during exercise in normoxia and hypoxia in subjects who showed a rise in blood viscosity after exercise. The hypothesis is that the magnitude of IHHC beneficial effects is related to change in blood viscosity and its determinants.

Inclusion Criteria:to be aged between 44 and 65 years old.for women, post-menopausal will be considered.for hypertensive group, stage 1 hypertension: systolic blood pressure (140-159 mmHg) and/or diastolic blood pressure (90-99 mmHg).free of other disease than hypertension and free of anti-hypertensive treatment medication.Hypertensive participants with 14 days of hypertensive drugs wash-out.able to complete all sessions.able to give consent.Exclusion Criteria:Peripheral arterial diseaseAtrial fibrillationHypoxic congenital heart diseasesPulmonary Hypertensionusing dietary supplements or drugs which interfere with the measurements (nitrate supplementation)