Da. Kirby et al., EFFECTS OF BETA-ADRENERGIC-RECEPTOR BLOCKADE ON HEMODYNAMIC-CHANGES ASSOCIATED WITH OBSTRUCTIVE SLEEP-APNEA, Physiology & behavior, 58(5), 1995, pp. 919-923
To study the effects of airway obstruction (AWO) and arousal on corona
ry blood flow, mean arterial pressure (MAP) and heart rate (HR), pigs
were chronically instrumented with arterial catheters, Doppler flow pr
obes on the left circumflex coronary artery, and electrodes for determ
ination of sleep stages. A modified balloon catheter was placed in the
trachea to obstruct the upper airway during sleep. Following control
studies, the role of beta adrenergic receptors in hemodynamic response
s to AWO was assessed by administering propranolol, a beta adrenorecep
tor blocking agent. In control studies, during nonrapid eye movement s
leep (NREM), MAP was 85 +/- 2 mmHg before AWO and increased by 8 +/- 2
mmHg upon arousal. Mean arterial pressure was lower during rapid eye
movement (REM) sleep (64 +/- 2 mmHg) and the increase upon arousal was
threefold greater (22 +/- 2 mmHg). Heart rate was similar in both sle
ep stages (NREM 123 +/- 5 bpm; REM 125 +/- 6 bpm) and increased signif
icantly upon arousal (NREM, 11 +/- 2 bpm; REM, 18 +/- 3 bpm increase.)
Coronary blood flow was similar during both stages (NREM 44 +/- 5 ml/
min; REM 44 +/- 6 ml/min) and increased by 13% (NREM) and 22% (REM) du
ring arousal. Coronary vascular resistance increased significantly by
17% during arousal from AWO during REM sleep. All changes were signifi
cant at p < 0.05. Following beta adrenergic receptor blockade studies
using propranolol, baseline HR was reduced in NREM sleep and HR and co
ronary blood flow increases during arousal from apnea were eliminated.
Adrenoreceptor blockade studies suggest that these effects were media
ted by the beta adrenergic component of the sympathetic nervous system
.