Abstract
New Findings What is the topic of the review? Sympathoexcitation and sympathetic control of blood pressure at high altitude. What advances does it highlight? Sustained sympathoexcitation is fundamental to integrative control of blood pressure in humans exposed to chronic hypoxia. The largest gaps in current knowledge are in understanding the complex mechanisms by which central sympathetic outflow is regulated at high altitude. High altitude (HA) hypoxia is a potent activator of the sympathetic nervous system, eliciting increases in sympathetic vasomotor activity. Microneurographic evidence of HA sympathoexcitation dates back to the late 20th century, yet only recently have the characteristics and underpinning mechanisms been explored in detail. This review summarises recent findings and highlights the importance of HA sympathoexcitation for the regulation of blood pressure in lowlanders and indigenous highlanders. In addition, this review identifies gaps in our knowledge and corresponding avenues for future study.
Highlights
High altitude (HA) exposure is a significant stressor of cardiovascular function and autonomic regulation
Independent of genotypic differences, can influence MSNA (Notay et al, 2017), these findings indicate that divergent pathways of TA B L E 1 Summary of microneurographic studies in lowlander populations at HA
It has previously been suggested that sympathetic vasomotor outflow is augmented in lowlanders at HA to compensate for a reduction in circulating blood volume (Hansen and Sander, 2003)
Summary
High altitude (HA) exposure is a significant stressor of cardiovascular function and autonomic regulation. In the first published microneurographic study at HA, Duplain et al, (1999) reported an augmented MSNA burst frequency following 24– 36 h at 4559 m. Elevated MSNA persisted for 3 days following descent to sea level These seminal studies were followed by a 15-year hiatus in published HA microneurographic data. A number of studies have presented new data, including the first MSNA recordings in highland native populations, and address the mechanisms underpinning HA sympathoexcitation. This recent work provides the primary focus for this Hot Topics Review
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