Key result
Autonomic blockade identifies HF Power and Sympathetic Index as the most reliable HRV metrics.
Why the study?
The sensitivity and sustainability of specific HRV parameters for autonomic nervous system modulation after pharmacological blockade remain debated.
Does pharmacological autonomic blockade with atropine or propranolol consistently alter specific heart rate variability metrics in a rat model?
Does pharmacological autonomic blockade with atropine or propranolol consistently alter specific heart rate variability metrics in a rat model?
A sustainability score framework identified HF Power and SI as the most reliable HRV metrics for assessing rapid parasympathetic and sympathetic autonomic changes, respectively, in rat models.
Answers are grounded in this paper and cite their sources.
HF Power and Sympathetic Index may be preferred HRV metrics in rat autonomic studies; hypothesis-generating for human validation and leaves clinical translation open.
Background: While Heart Rate Variability (HRV) is a cornerstone of non-invasive autonomic assessment, the sensitivity and sustainability of specific HRV parameters remain debated. This study introduces a "sustainability score" to systematically validate which metrics best reflect autonomic nervous system (ANS) modulation following pharmacological blockade. Methods: Ten male Sprague-Dawley rats were implanted with ECG electrodes. After recovery, rats underwent randomized atropine (1 mg/kg, intraperitoneal) and propranolol (10 mg/kg, intraperitoneal) sessions separated by at least 3 days. Baseline ECG was recorded for 30 min before each session, followed by 90-min post-drug ECG recording. HRV parameters were analyzed in sequential 15-min and 30-min segments. Reliability was assessed using average p-values across post-drug segments and a sustainability score, defined as the number of segments significantly different from baseline. Results: After atropine, HF Power showed the strongest rapid parasympathetic-related response in 15-min segments, with the lowest average p-value (0.1476) and highest sustainability score (4), followed by RSA (p=0.16148; score=4). HFn was less reliable in 15-min segments (p=0.23147; score=2) but became the most reliable parasympathetic-related metric in 30-min segments (p=0.0001; score=3). After propranolol, SI was the most reliable sympathetic-related metric in both 15-min (p=0.18225; score=2) and 30-min segments (p=0.0393; score=2), while SD2/SD1 showed the strongest 30-min sympathovagal-balance response (p=0.0200; score=3). Conclusion: HF Power is recommended for rapid parasympathetic-related assessment in short windows, HFn for longer-window parasympathetic assessment, SI for sympathetic-assessment, and SD2/SD1 for 30-min sympathovagal-balance analysis. Sustainability scoring provides a structured framework for selecting ECGderived autonomic markers.
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Ali et al. (2026) studied Normal rats (n=10). Pharmacological autonomic blockade (atropine and propranolol) vs. Baseline prior to drug administration was evaluated on Reliability (average p-values) and sustainability score of HRV parameters. Pharmacological autonomic blockade in rats showed HF Power as the most reliable rapid parasympathetic metric and Sympathetic Index as the most reliable sympathetic metric based on sustainability scoring.
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