Ahmed, SofiaNicholl, David2012-08-282015-07-312012-08-282012Nicholl, D. (2012). Obstructive sleep apnea treatment with continuous positive airway pressure therapy improves renin angiotensin system activity (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27159http://hdl.handle.net/11023/162Background Obstructive sleep apnea (OSA) is strongly associated with cardiorenal disease. Limited studies suggest that renin angiotensin system (RAS) activation may mediate this relationship. We sought to determine the effect of continuous positive airway pressure (CPAP) on the hemodynamic and circulating RAS component responses to Angiotensin II (AngII) infusion. Methods Twelve moderate-severe OSA subjects with hypoxia were studied in high-salt balance before and 1 month after starting treatment with CPAP. Mean arterial pressure (MAP), plasma renin activity (PRA), and aldosterone were measured in response to AngII (3ng/kg/minx30min, 6ng/kg/minx30min, 30min recovery). Results CPAP corrected OSA; reduced MAP (95±2 vs 89±2mmHg, p=0.019), aldosterone (179±27 vs 115±14pmol/L, p=0.006), and protein excretion (69[39,341] vs 48[22,204]mg/day, p=0.002); and increased MAP sensitivity to 3ng/kg/min AngII (10±2 vs 15±2mmHg, p=0.019), but not 6ng/kg/min AngII or recovery. RAS component sensitivity was unaffected. Conclusions CPAP treatment decreased RAS activity and increased hemodynamic sensitivity to AngII, supporting a role for the RAS in mediating OSA-induced hypertension.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Medicine and Surgeryobstructive sleep apnearenin angiotensin systemcontinuous positive airway pressureangiotensin IIblood pressuremaster thesis10.11575/PRISM/27159