Hypertension caused by chronic intermittent hypoxia – influence of chemoreceptors and sympathetic nervous system

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BackgroundThe sleep apnea syndrome (SAS) is a common health problem with a 30% prevalence among patients with so-called essential hypertension.ObjectivePrompted by this epidemiologic link we tried to find out whether there is a cause–effect relationship between SAS and systemic hypertension.DesignWe developed an animal model to simulate defined aspects of the SAS. Rats were exposed to chronic repetitive hypoxia for 7 h per day and their blood pressure was measured by invasive methods.ResultsWe found that 30 days of intermittent hypoxia sufficed for the development of a significant elevation of blood pressure. The co-exposure to hypoxia and hypercapnia had no additional effect. Surgical denervation of peripheral chemoreceptors prevented the increase in arterial blood pressure. Adrenal demedullation and chemical denervation of the peripheral sympathetic nervous system by 6-hydroxy dopamine also prevented the increase.ConclusionsOur data imply that repetitive hypoxemia in SAS is probably the cause of the high prevalence of systemic hypertension in this population and that peripheral chemoreceptors and the sympathetic nervous system play important roles in this pathophysiologic process.

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