Baroreceptor control of central and regional hemodynamics with isoflurane in the dog

Central and regional hemodynamics were studied at five levels of carotid sinus baroreceptor stimulation and three isoflurane levels. Apart from iliac blood flow, all regional blood flows, together with mean aortic pressure, power and flow decreased in response to an increasing anesthetic level and/or carotid sinus baroreceptor stimulation. These effects were additive with no significant interaction between the two experimental factors. At the carotid sinus reflex set point pressure, isoflurane attenuated the ability of carotid sinus baroreceptors to change mean aortic pressure and power together with the maximum capacity of the carotid sinus baroreceptors to produce vasoconstriction. The maximum capacity of the carotid sinus baroreceptors to produce vasodilation was unaffected by isoflurane. Vagotomy only modified hemodynamic set point values at low isoflurane levels, increasing regional resistances at the expense of flow except for the iliac bed. Following vagotomy, reflex gain was increased as was the maximum capacity of the cardiovascular system to vasoconstrict and vasodilate in response to carotid sinus pressure stimulation, together with the range of arterial pressure control.