Cardiac Autonomic Control Reflects Sympathovagal Changes Associated With Withholding Urination

Area of Science:

• Physiology
• Autonomic Nervous System Research
• Cardiovascular Regulation

Background:

• Bladder distention increases sympathetic nervous system (SNS) tonus, leading to an urge to urinate.
• Heart rate variability (HRV) is a key indicator of autonomic nervous system (sympathovagal) balance.
• Assessing sympathovagal changes during bladder distention is crucial for understanding physiological responses.

Purpose of the Study:

• To investigate if HRV accurately reflects increased sympathovagal balance in healthy young males experiencing bladder distention.
• To determine the utility of HRV as a non-invasive tool for monitoring autonomic responses during the urge to urinate.

Main Methods:

• 11 healthy young males underwent 5-minute electrocardiogram (ECG) recordings to determine HRV.
• Recordings were taken before and after a 3.5-hour period of withholding urination.
• Key HRV parameters analyzed included heart rate (HR), total power (TP), SDNN, pNN50, LF, HF, and LF/HF ratio.

Main Results:

• Withholding urination did not significantly alter heart rate (HR).
• Significant decreases were observed in total power (TP), SDNN, and pNN50.
• Normalized low frequency (LFnu) and the LF/HF ratio significantly increased, indicating heightened sympathetic activity.

Conclusions:

• Elevated LF/HF ratio and reduced SDNN/pNN50 demonstrate HRV's effectiveness in reflecting increased sympathetic tonus during bladder distention.
• HRV serves as a viable non-invasive method for assessing sympathovagal changes related to urination.
• Avoiding urination during HRV recordings is recommended for accurate measurements.