Effects of vagotomy on cardiovascular response to periodic apneas in sedated pigs.
There are few studies investigating the influence of vagally mediated reflexes on the cardiovascular response to apneas. In 12 sedated preinstrumented pigs, we studied the effects of vagotomy during apneas, controlling for apnea periodicity and thoracic mechanical effects. Nonobstructive apneas were produced by paralyzing and mechanically ventilating the animals, then turning the ventilator off and on every 30 s. Before vagotomy, relative to baseline, apnea caused increased mean arterial pressure (MAP; +19 +/- 25%, P < 0.05), systemic vascular resistance (SVR; +33 +/- 16%, P < 0.0005), and heart rate (HR; +5 +/- 6%, P < 0.05) and decreased cardiac output (CO) and stroke volume (SV; -16 +/- 10% P < 0.001). After vagotomy, no significant change occurred in MAP, SVR, and SV during apneas, but CO and HR increased relative to baseline. HR was always greater ( approximately 14%, P < 0.01) during the interapneic interval compared with during apnea. We conclude that vagally mediated reflexes are important mediators of the apneic pressor response. HR increases after apnea termination are related, at least in part, to nonvagally mediated reflexes.
Slamowitz
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D
Pulmonary and Critical Care Division, Long Island Jewish Medical Center, Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York 11042, USA.
Chen
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L
Scharf
S M
SM
D000818:Animals; D001049:Apnea / Q000503:physiopathology*; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D012121:Respiration, Artificial; D013318:Stroke Volume / Q000502:physiology; D013552:Swine; D014628:Vagotomy; D014655:Vascular Resistance / Q000502:physiology
D006993:Hypnotics and Sedatives