Effect of central hypervolemia on respiratory function.
Effects of central hypervolemia on respiratory function and compensatory capabilities of the respiratory system were studied in the anesthetized, vagally intact or vagotomized rats. Central hypervolemia was induced by a head-down tilt on -30 degree rotation. The tilt evoked an elevation of central venous pressure (from -2+/-0.4 cmH2O to 3.9+/-0.8 cmH2O). At 30 min after tilting, airway resistance and negative intrathoracic pressure (indirect measure of respiratory effort) significantly increased, whereas inspiratory flow, tidal volume, and minute ventilation decreased. Load compensatory response was strongly weakened. The tilt-induced esophageal pressure augmentation was suppressed by transection of the vagal nerves. In vagotomized animals inspiratory swings of the intrathoracic pressure increased barely to 116+/-15%, whereas they increased to 216+/-17% of control in vagally intact animals (P<0.05). We conclude that central hypervolemia increases mechanical loading and weakens compensatory capabilities of the respiratory system. Vagal afferents have a part in the realization of the respiratory response to central hypervolemia.
Alexandrova
N P
NP
Laboratory of Respiration Physiology, Pavlov Institute of Physiology, Russian Academy of Science, Saint-Petersburg, Russia. nina@vga.infran.ru
Donina
Z A
ZA
Danilova
G A
GA
D000222:Adaptation, Physiological; D000344:Afferent Pathways / Q000503:physiopathology; D000403:Airway Resistance; D000818:Animals; D001810:Blood Volume; D002319:Cardiovascular System / Q000294:innervation*; D002496:Central Venous Pressure; D004947:Esophagus / Q000503:physiopathology; D018495:Fluid Shifts; D018475:Head-Down Tilt; D023421:Models, Animal; D011312:Pressure; D012123:Pulmonary Ventilation; D051381:Rats; D015656:Respiratory Mechanics; D016683:Supine Position; D013990:Tidal Volume; D014139:Tracheostomy; D014628:Vagotomy; D014630:Vagus Nerve / Q000503:physiopathology* / Q000601:surgery