High subcutaneous nerve activity in noise-associated ventricular arrhythmias

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Research
• Environmental Health

Background:

• Environmental noise is linked to autonomic nervous system (ANS) dysregulation and cardiovascular disease.
• Subcutaneous nerve activity (SCNA) and heart rate variability (HRV) are key indicators of ANS function and arrhythmias.
• Mechanisms of noise-induced arrhythmogenesis remain unclear.

Purpose of the Study:

• To investigate the role of ANS modulation in noise-induced ventricular arrhythmias (VAs).
• To analyze SCNA and HRV in response to environmental noise exposure.
• To elucidate the pathways linking noise to cardiac arrhythmias.

Main Methods:

• C57BL/6 mice were exposed to broadband noise (85 dB) for 28 days or served as controls.
• Groups received either vehicle or 6-hydroxydopamine (chemical sympathectomy).
• ECG and SCNA were measured simultaneously during baseline, cold pressor test, and recovery phases.

Main Results:

• Noise exposure significantly increased SCNA (P ≤ .030) and decreased HRV parameters (P ≤ .034), indicating sympathetic hyperactivity.
• 6-hydroxydopamine treatment blunted the noise-induced SCNA increase (P ≤ .012).
• The noise + vehicle group exhibited significantly more premature ventricular contractions (P = .013), often preceded by SCNA bursts.

Conclusions:

• Noise exposure induces VAs through sympathetic activation, confirmed by increased SCNA and reduced HRV.
• Autonomic dysregulation is the central mechanism underlying noise-induced arrhythmogenesis.
• SCNA is a validated tool for assessing ANS function and arrhythmogenesis in mice.