Intermittent Hypoxic Exposure Reduces Endothelial Dysfunction

Abstract

Intermittent exposure to hypoxia (IHE) increases the production of reactive oxygen and nitrogen species as well as erythropoietin (EPO), which stimulates the adaptation to intense physical activity. However, several studies suggest a protective effect of moderate hypoxia in cardiovascular disease (CVD) events. The effects of intense physical activity with IHE on oxi-inflammatory mediators and their interaction with conventional CVD risk factors were investigated. Blood samples were collected from elite athletes (control n=6, IHE n=6) during a 6-day IHE cycle using hypoxicator GO2 altitude. IHE was held once a day, at least 2 hours after training. In serum, hydrogen peroxide (H2O2), nitric oxide (NO), 3-nitrotyrosine (3-Nitro), proinflammatory cytokines (IL-1β and TNFα), high sensitivity C-reactive protein (hsCRP), and heat shock protein 27 (HSP27) were determined by the commercial immunoenzyme (ELISA kits) or colorimetric methods. Serum erythropoietin (EPO) level was measured by ELISA kit every day of hypoxia. IHE was found to significantly increase H2O2, NO, and HSP27 but to decrease 3NT concentrations. The changes in 3NT and HSP27 following hypoxia proved to enhance NO bioavailability and endothelial function. In the present study, the oxi-inflammatory mediators IL-1β and hsCRP increased in IHE group but they did not exceed the reference values. The serum EPO level increased on the 3rd day of IHE, then decreased on 5th day of IHE, and correlated with NO/H2O2 ratio (rs=0.640, P<0.05). There were no changes in haematological markers contrary to lipoproteins such as low-density lipoprotein (LDL) and non-high-density lipoprotein (non-HDL) which showed a decreasing trend in response to hypoxic exposure. The study demonstrated that IHE combined with sports activity reduced a risk of endothelial dysfunction and atherogenesis in athletes even though the oxi-inflammatory processes were enhanced. Therefore, 6-day IHE seems to be a potential therapeutic and nonpharmacological method to reduce CVD risk, especially in elite athletes participating in strenuous training.

Assessment of Serum Neopterin as a Biomarker in Peripheral Artery Disease

“…3NT measurement is required to confirm the presence of peroxynitrite in blood [33]. In our previous paper we argued that the detection and quantification of 3NT could be used as an indicator for the pathological processes in vascular endothelium [34].…”

Dipeptide Extract Modulates the Oxi-Antioxidant Response to Intense Physical Exercise

“…For example, diabetic rats which received carnosine showed a 20% reduction in advanced glycation end products, a 24% reduction in serum reactive oxygen and nitrogen species, and a 36% reduction in oxidantmediated protein damage [33]. Reactive oxygen and nitrogen species production is known to increase dramatically in skeletal muscles, endothelium and erythrocytes following intense exercise [4,34,35]. Furthermore, persistent exercise-induced inflammation in tissues is accompanied by excessive H 2 O 2 generation and reduced NO bioavailability [4].…”

Intermittent Hypoxic Training as an Effective Tool for Increasing the Adaptive Potential, Endurance and Working Capacity of the Brain

“…IHT results in significant improvement of the autonomic nervous system functioning, arterial stiffness, arterial endothelial function, and haemorheological function ( Zembron-Lacny et al, 2020 ; Park et al, 2022 ) IHT also enhances cardiac muscle resistance to hypoxia via increasing the activity of the myocardial metabolic enzymes and percentage of α-myosin heavy chain ( Cai et al, 2010 ). Activation of antioxidant enzymes and stress proteins may also be part of the mechanisms contributing to the cardioprotection of the intermittent hypoxic adaptation.…”