Cardiopulmonary control in sleeping Sprague-Dawley rats treated with hydralazine.
To test the hypothesis that hydralazine can suppress spontaneous sleep-related central apnea, respiratory pattern, blood pressure, and heart period were monitored in Sprague-Dawley rats. In random order and on separate days, rats were recorded after intraperitoneal injection of 1) saline or 2) 2 mg/kg hydralazine. Normalized minute ventilation (NVI) declined significantly with transitions from wake to non-rapid-eye-movement (NREM) sleep (-5.1%; P = 0.01) and rapid-eye-movement (REM) sleep (-4.2%; P = 0.022). Hydralazine stimulated respiration (NVI increased by 21%; P < 0.03) and eliminated the effect of state on NVI. Blood pressure decreased by 17% after hydralazine, and the correlation between fluctuations in mean blood pressure and NVI changed from strongly positive during control recordings to weakly negative after hydralazine (P < 0.0001 for each). Postsigh and spontaneous apneas were reduced during NREM and REM sleep after hydralazine (P < 0.05 for each). This suppression was strongly correlated with the reduction in blood pressure and with the degree of respiratory stimulation. We conclude that mild hydralazine-induced hypotension leads to respiratory stimulation and apnea suppression.
Carley
D W
DW
Section of Respiratory and Critical Care Medicine, University of Illinois College of Medicine at Chicago, Chicago, Illinois 60612, USA.
Trbovic
S M
SM
Bozanich
A
A
Radulovacki
M
M
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects; D004576:Electromyography / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D006830:Hydralazine / Q000494:pharmacology*; D008297:Male; D010991:Plethysmography; D017286:Polysomnography / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D015656:Respiratory Mechanics / Q000187:drug effects*; D012890:Sleep / Q000502:physiology*; D012891:Sleep Apnea Syndromes / Q000503:physiopathology; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*
D014665:Vasodilator Agents; D006830:Hydralazine