Modulation of carotid sinus baroreceptor reflex by sciatic nerve stimulation

Area of Science:

• Cardiovascular Physiology
• Neuroscience

Background:

• The carotid sinus baroreceptor reflex is crucial for regulating arterial pressure and heart rate.
• Sciatic nerve stimulation (SNS) can influence autonomic nervous system activity.

Purpose of the Study:

• To investigate the effect of SNS on the baroreceptor reflex control of arterial pressure and heart rate in vagotomized cats.
• To determine if SNS modulates the gain of the arterial pressure-intrasinus pressure (ISP-AP) and heart rate-intrasinus pressure (ISP-HR) relationships.

Main Methods:

• Anesthetized, immobilized, and vagotomized cats were used.
• Sciatic nerve stimulation (SNS) was applied at various intrasinus pressure (ISP) levels.
• Arterial pressure (AP) and heart rate (HR) were recorded before and during SNS to analyze ISP-AP and ISP-HR relationships.

Main Results:

• SNS significantly decreased the gain of the ISP-AP relationship (P < 0.005) and the ISP-HR relationship (P < 0.05).
• Modulation of the ISP-AP relationship gain by SNS was attributed to changes in cardiac output (CO), not total peripheral resistance (TPR).
• SNS increased AP, HR, and TPR, while decreasing CO.

Conclusions:

• SNS attenuates the sensitivity of arterial pressure and heart rate responses within the carotid sinus baroreceptor reflex.
• The observed inhibition of the reflex arterial pressure response during SNS is primarily mediated by modulation of the cardiac output response.