Hypotension reduces sleep apneas in Zucker lean and Zucker obese rats

The effects of hypotension and obesity on spontaneous apnea (SA) and post-sigh sleep apnea (PSA) were studied in Zucker rats by monitoring blood pressure, respiration, and sleep state for 6 hours. Hypotension produced by intraperitoneal administration of hydralazine (2 mg/kg) was associated with reduced SA and PSA expression in nonrapid eye movement sleep in both lean and obese rats. In both animal groups, hypotension reduced rapid eye movement (REM) sleep by 50% but exerted no significant effect on REM-related expression of SA. Blood pressure lowering also correlated with increased respiratory rate and inspired minute ventilation during sleep, suggesting that the effects of hypotension on apnea 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.