Systemic Hypoxia Increases Circulating Concentration of Apelin in Humans

Area of Science:

• Cardiovascular Physiology
• Human Physiology
• Endocrinology

Background:

• Apelin is a hormone crucial for cardiovascular regulation.
• Previous studies in animals and cell cultures indicated that hypoxia increases apelin levels.
• The effect of hypoxia on human apelin levels remained uninvestigated.

Purpose of the Study:

• To determine if breathing a normobaric hypoxic gas mixture increases circulating apelin concentration in healthy human males.
• To investigate the temporal response of apelin levels following acute hypoxic exposure.

Main Methods:

• Ten healthy young men were exposed to a normobaric hypoxic gas mixture (11% O2) for 1 hour.
• Blood samples were collected at baseline, 2 hours, and 24 hours post-exposure.
• Circulating apelin concentrations were analyzed using validated assays.

Main Results:

• Hypoxic exposure significantly reduced arterial oxygen saturation to approximately 73%.
• Apelin concentrations remained stable at baseline and 2-hour time points.
• A significant increase in apelin concentration (approximately 67%) was observed at the 24-hour time point compared to baseline and 2-hour levels.

Conclusions:

• Acute systemic hypoxia in humans leads to an increase in circulating apelin concentration.
• These findings in humans align with previous observations from cell culture and animal studies.
• The study confirms the role of apelin as a response to hypoxic conditions in humans.