Micro- and macrovascular function in the highest city in the world: a cross sectional study

Area of Science:

• Physiology
• Cardiovascular Research
• Altitude Medicine

Background:

• Vascular responses to hypoxia in healthy high-altitude natives and chronic mountain sickness (CMS) are not fully understood.
• The study investigated the role of inflammation, oxidative stress, and nitrosative stress on endothelial function in micro- and macrocirculation.
• This research included healthy Andeans at varying altitudes and patients with CMS.

Purpose of the Study:

• To examine the impact of chronic hypoxia and CMS on vascular function.
• To elucidate the role of inflammation and oxidative/nitrosative stress in endothelial responses.
• To compare micro- and macrocirculatory function in different altitude-exposed groups.

Main Methods:

• 94 men were studied: lowlanders, healthy highlanders at 3800m and 5100-5300m (La Rinconada), and patients with mild or moderate/severe CMS.
• Vascular reactivity was assessed using local thermal hyperemia (microcirculation) and flow-mediated dilation (macrocirculation).
• Endothelium-independent function was evaluated using glyceryl trinitrate.

Main Results:

• Vascular function (conductance, blood flow velocity, macrocirculation) decreased progressively with increasing altitude.
• CMS further impaired macrocirculation, while glyceryl trinitrate normalized function.
• Oxidative stress and nitric oxide metabolites increased with altitude; inflammation correlated with declining micro- and macrovascular function in healthy highlanders.

Conclusions:

• Chronic hypoxia negatively affects both micro- and macrovascular function.
• Chronic mountain sickness exacerbates the negative impact on macrovascular function.
• Inflammation is a significant factor in the decline of vascular function associated with high-altitude exposure.