HYPOTENSION REDUCES SLEEP APNEAS IN ZUCKER LEAN AND ZUCKER OBESE RATS

The effects of hypotension and obesity on spontaneous apnea (SA) and p ost-sigh sleep apnea (PSA) were studied in Zucker rats by monitoring b lood pressure, respiration, and sleep state for 6 hours. Hypotension p roduced by intraperitoneal administration of hydralazine (2 mg/kg) was associated with reduced SA and PSA expression in nonrapid eye movemen t sleep in both lean and obese rats. In both animal groups, hypotensio n reduced rapid eye movement (REM) sleep by 50% but exerted no signifi cant effect on REM-related expression of SA. Blood pressure lowering a lso correlated with increased respiratory rate and inspired minute ven tilation during sleep, suggesting that the effects of hypotension on a pnea expression may arrive via modulation of respiratory drive. These findings emphasize the interdependence of cardiorespiratory functions and may have implications regarding the mechanisms of central apnea in man.