Central and peripheral chemoreflexes in humans with treated hypertension

Area of Science:

• Cardiovascular Physiology
• Respiratory Control
• Hypertension Pathophysiology

Background:

• Increased peripheral chemoreflex sensitivity is a known pathogenic feature in human hypertension (HTN).
• Both central and peripheral chemoreflex sensitivities are reportedly augmented in animal models of HTN.
• The role of augmented central chemoreflex sensitivity in human HTN remains less understood.

Purpose of the Study:

• To test the hypothesis that both central and combined central and peripheral chemoreflex sensitivities are augmented in human HTN.
• To investigate the relationship between global cerebral blood flow (gCBF) and chemoreflex responses in HTN.

Main Methods:

• Fifteen participants with HTN and 13 normotensive (NT) controls underwent modified rebreathing protocols.
• Ventilation and muscle sympathetic nerve activity (MSNA) were measured during isoxic hyperoxia (central activation) and isoxic hypoxia (combined activation).
• Ventilatory and sympathetic chemoreflex sensitivities and recruitment thresholds were calculated; gCBF was also measured.

Main Results:

• Central ventilatory and sympathetic chemoreflex sensitivities were significantly greater in HTN participants compared to NT controls.
• No significant differences were observed in combined central and peripheral chemoreflex sensitivities or recruitment thresholds between groups.
• Lower gCBF was associated with earlier recruitment thresholds for both ventilation and MSNA during central chemoreflex activation.

Conclusions:

• Central ventilatory and sympathetic chemoreflex sensitivities are augmented in human hypertension.
• These findings suggest a potential contributory role of central chemoreceptors in HTN pathogenesis.
• Targeting the central chemoreflex may offer a therapeutic strategy for certain forms of hypertension.