Responses of sympathetic nerves to programmed ventricular stimulation

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Regulation

Background:

• Ventricular arrhythmias can decrease arterial pressure and alter filling pressures.
• These hemodynamic changes may elicit reflex adjustments in sympathetic nerve activity.

Purpose of the Study:

• To investigate if programmed ventricular stimulation alters renal sympathetic nerve activity.
• To quantify these changes and identify the mediating cardiovascular reflexes.

Main Methods:

• Experiments conducted on 14 anesthetized dogs.
• Recorded arterial pressure, atrial pressure, and renal sympathetic nerve activity.
• Administered single and double programmed ventricular stimuli before and after sinoaortic denervation.

Main Results:

• Single and double ventricular stimuli decreased diastolic arterial pressure and increased renal sympathetic nerve activity.
• Changes were related to stimulus prematurity and significantly reduced after sinoaortic denervation.
• Programmed stimulation also increased cardiac sympathetic traffic.

Conclusions:

• Decreased arterial pressure from programmed ventricular stimuli increases cardiac and renal sympathetic nerve activity.
• These increases are mediated by sinoaortic baroreflexes.