Objective To evaluate the levels of big endothelin- 1( Big ET- 1) and nitric oxide( NO) in elderly hypertensive patients with and without moderate to severe obstructive sleep apnea- hypopnea syndrome( OSAHS). Methods 144 hypertension subjects were enrolled from our hospital from August 2010 to July 2013. The mean age were 65. 5 ± 5. 8years. Based on OSAHS,the subjects were divided into with OSAHS group( n = 96) and without OSAHS group( n = 48). We obtained the following data: body mass index( BMI); 24- ambu...