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Updated: May 4, 2026
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Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response
Published on: November 12, 2014
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Sympathetic nerve activity and simulated diving in healthy humans
Abu Shamsuzzaman1, Michael J Ackerman2, Fatima Sert Kuniyoshi2
1Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Mayo Clinic, Rochester, MN, USA.
Autonomic Neuroscience : Basic & Clinical
|December 26, 2013
Summary
Simulated diving using cold water and breath-holding strongly activates the nervous system and causes significant heart rate reduction. This powerful stimulus reveals synergistic autonomic responses, offering insights into cardiovascular events.
Area of Science:
- Physiology
- Autonomic Nervous System
- Cardiovascular Regulation
Background:
- The diving reflex is a physiological response to immersion in cold water.
- Understanding the autonomic nervous system's role in the diving reflex is crucial for explaining cardiovascular events during asphyxia or swimming.
Purpose of the Study:
- To develop a simple method for simulating the human diving reflex.
- To measure neural and circulatory responses during simulated diving.
- To investigate the synergistic effects of facial cold exposure and apnea on autonomic responses.
Main Methods:
- Simulated diving using facial cold exposure and apnea in 56 healthy volunteers.
- Measurement of muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate.
- Analysis of autonomic responses to individual stimuli versus combined stimuli.
Main Results:
- Simulated diving significantly increased muscle sympathetic nerve activity (MSNA), blood pressure, and vascular resistance.
- Heart rate reduction (bradycardia) was observed only in the late phase of simulated diving.
- Total MSNA during simulated diving was greater than the sum of responses to individual stimuli, indicating synergistic effects.
Conclusions:
- Simulated diving is a potent stimulus for sympathetic nerve activity.
- The diving reflex elicits synergistic sympathetic and parasympathetic responses.
- Findings provide insights into autonomic triggers for cardiovascular events in conditions like sleep apnea and congenital long QT syndrome.
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