Obstructive sleep apnea and hypertension: Are peripheral chemoreceptors involved?

The mechanism of pathogenesis of hypertension in patients with obstructive sleep apnea (OSA) is unknown. Many investigators point to the high sympathe tic nervous system activity (SNS) observed in OSA patients. However, there is no clear explanation as to the mechanism for the development of SNS hype ractivity in these patients. A common feature of patients with OSA is repet itive bouts of transient hypoxemia during sleep. Repetitive transient hypox emia in rats has resulted in hypertension. In OSA patients, resolution of n octurnal hypoxemia with CPAP has corrected nocturnal and diurnal hypertensi on. Also, exposure to hyperoxia reduces blood pressure and sympathetic acti vity in OSA patients, but not in normals. These data suggest a significant role of peripheral chemoreceptors in the regulation of vascular tone. We hy pothesize that peripheral chemoreceptors significantly contribute to the pa thogenesis of hypertension in patients with OSA and that this is associated with chemoreceptor hyperactivity. This implies that correcting the intermi ttent nocturnal hypoxemia alone may prevent the cardiovascular morbidity as sociated with obstructive sleep apnea. (C) 2001 Harcourt Publishers Ltd.