AJP - Heart and Circulatory Physiology, Vol 239, Issue 5 681-H691, Copyright © 1980 by American Physiological Society
Effects of anesthesia on carotid sinus reflex control of arterial hemodynamics in the dog
R. H. Cox and R. J. Bagshaw
The detailed characteristics of the carotid sinus reflex control of
regional pressure-flow relations were compared in dogs anesthetized with
chloralose, pentobarbital, or halothane. The carotid sinuses were isolated
and perfused under conditions of controlled pulsatile pressure. Pressure
and flow were measured in the ascending aorta and the celiac, mesenteric,
renal, and iliac artery. Mean arterial pressure and peripheral resistance
were highest under chloralose and lowest under halothane. For cardiac
output this relation was reversed. Set point values of reflex gain and
overall range of control were similar under chloralose and halothane and
lowest under pentobarbital. These results were found both before and after
bilateral cervical vagotomy. Operating point values of regional resistance
were generally largest with chloralose and smallest with halothane.
Operating point sensitivities of regional resistances were generally
smallest under pentobarbital and similar under chloralose and halothane.
Vagotomy was associated with increases in set point values of mean arterial
pressure, set point gain, and overall range of control under all three
anesthetics. With chloralose as a reference, halothane does not depress
cardiovascular reflex mechanisms. Carotid sinus reflexes under halothane
were as sensitive and well maintained as they were under chloralose. These
reflexes were significantly depressed under pentobarbital compared with
chloralose.
