High numbers of circulating apoptotic endothelial cells may explain the endothelial dysfunction seen in patients with obstructive sleep apnea (OSA), according to a report in the June 1st issue of the American Journal of Respiratory and Critical Care Medicine.
"The increased levels of circulating apoptotic endothelial cells would mean less production of nitric oxide that is crucial to artery vasodilatation," Dr. Ali A. El Solh from the University of Buffalo School of Medicine and Biomedical Sciences, New York, told Reuters Health. "The less nitric oxide there is, the higher potentially is the risk of hypertension and acute heart attack."
Dr. El Solh and associates investigated the association between circulating apoptotic endothelial cells and vasomotor in 14 men with OSA and 10 healthy controls.
Patients with OSA had significantly higher numbers of circulating apoptotic endothelial cells than did the controls, the researchers report. The presence of circulating apoptotic endothelial cells correlated with the apnea-hypopnea index (AHI) and time with oxygen saturation below 90%, the results indicate, but not with arousal index.
Patients with increased circulating apoptotic endothelial cell counts also showed strong impairment of endothelial-dependent vasorelaxation, the investigators say.
After 8 weeks of continuous positive-airway pressure (CPAP) therapy, circulating apoptotic endothelial cell numbers were significantly reduced in almost all OSA patients, the researchers note. This implicates OSA "in the initiation of apoptotic machinery."
In patients with OSA, the investigators conclude, circulating apoptotic endothelial cells "may serve as a novel marker of vascular dysfunction, allowing risk stratification and monitoring of athero-modifying regimens."
Furthermore, "There are multiple therapeutic interventions that have been shown to improve or attenuate endothelial apoptosis, like angiotensin converting enzyme inhibitors and statins," Dr. El Solh pointed out. "Whether these drugs are effective in OSA in addition to CPAP is not known."