Key result
Atropine significantly increased steady-state heart rate to 164.8 bpm (p=0.009) and propranolol decreased it to 106.3 bpm (p=0.047) compared to 137.1 bpm in control adult medaka.
Why the study?
Evaluating cardiac autonomic nervous system modulation noninvasively without anesthesia has been challenging in small fish disease models, as electrocardiography is invasive and anesthesia disturbs autonomic activity.
Does autonomic nervous system modulation affect heart rate variability frequency characteristics in unanesthetized adult medaka?
Does autonomic nervous system modulation affect heart rate variability frequency characteristics in unanesthetized adult medaka?
Absolute Event Rate: 164.8% vs 137.1%
p-value: p=0.009
This study establishes a non-invasive method to evaluate autonomic nervous system modulation of heart rate variability in unanesthetized adult medaka, demonstrating frequency-dependent parasympathetic and sympathetic regulation.
Validates medaka for autonomic heart rate studies; leaves open translation to mammalian or clinical models.
Small teleosts have recently been established as models of human diseases. However, measuring heart rate by electrocardiography is highly invasive for small fish. The physiological nature and function of vertebrate autonomic nervous system (ANS) modulation of the heart has traditionally been investigated in larvae with an incompletely developed ANS or in anesthetized adults, whose ANS activity may possibly be disturbed under anesthesia. Here, we defined the frequency characteristics of heart rate variability (HRV) modulated by the ANS from observations of heart movement in high-speed movie images and changes in ANS regulation under environmental stimulation in unanesthetized adult medaka ( Oryzias latipes ), a small teleost. The HRV was significantly reduced by atropine (1 mM) in the 0.25 – 0.65 Hz and by propranolol (100 μM) at 0.65–1.25 Hz range, suggesting that HRV in adult medaka is modulated by both the parasympathetic and sympathetic nervous systems within these frequency ranges. Such modulations of HRV by the ANS were remarkably suppressed in anesthetized adult medaka. Continuous exposure to light suppressed HRV only in the 0.25 – 0.65 Hz range, indicating parasympathetic withdrawal. The power of HRV increased along developmental processes. These results suggest that ANS modulation of the heart in adult medaka is frequency-dependent phenomenon, and that the impact of long-term environmental stimuli on ANS activities can be precisely evaluated in unanesthetized adult fish using this method.
No takes yet. Share an insight, caveat, or question.
Watanabe‐Asaka et al. (2022) studied Healthy adult medaka (animal model). Atropine and Propranolol vs. Control (no drug) was evaluated on Steady-state heart rate (p=0.009). Atropine significantly increased steady-state heart rate to 164.8 bpm (p=0.009) and propranolol decreased it to 106.3 bpm (p=0.047) compared to 137.1 bpm in control adult medaka.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: