Dynamic and static conditioning pressures evoke equivalent rapid resetting in rat aortic baroreceptors

Area of Science:

• Cardiovascular Physiology
• Neuroscience

Background:

• Previous studies suggest pulsatile pressure may sensitize carotid sinus baroreceptors.
• Rapid resetting of baroreceptors to elevated pressures can be affected by pulsatile conditioning.

Purpose of the Study:

• To investigate the effects of dynamic (pulsatile) pressure conditioning on aortic baroreceptor function.
• To determine if dynamic pressure exposure leads to long-lasting sensitization of aortic baroreceptors.

Main Methods:

• Aortic baroreceptors were studied in an in vitro preparation.
• Baroreceptors underwent 15-minute static and dynamic pressure conditioning at various mean arterial pressure levels.
• Static discharge properties (threshold, gain) were assessed using slow pressure ramps; aortic diameter was also measured.

Main Results:

• No significant difference was found in static pressure threshold before and after dynamic conditioning.
• Aortic baroreceptor static pressure threshold was linearly related to conditioning mean arterial pressure, with no difference between static and dynamic conditioning.
• Baroreceptor discharge rates returned to baseline quickly after dynamic conditioning; vessel diameter changes did not play a role.

Conclusions:

• Dynamic pressure inputs do not appear to cause long-lasting sensitization of aortic baroreceptors.
• Aortic baroreceptor responses to pressure changes are not significantly altered by short-term pulsatile conditioning.
• Findings contrast with some previous observations on carotid sinus baroreceptors.