Myocardial blood flow in the diving seal

Area of Science:

• Cardiovascular Physiology
• Marine Mammal Biology
• Comparative Physiology

Background:

• Grey seals display significant physiological changes during dives, including bradycardia and altered cardiac output.
• Understanding these adaptations is crucial for insights into cardiac function under stress.

Purpose of the Study:

• To investigate the regulation of myocardial blood flow in grey seals during simulated diving.
• To determine the relationship between cardiac output and coronary blood flow in diving seals.

Main Methods:

• Utilizing a combination of cardiovascular monitoring techniques in grey seals.
• Measuring heart rate, cardiac output, ventricular contractility, and coronary blood flow during simulated dives.

Main Results:

• A 90% reduction in coronary blood flow was observed, despite increased coronary driving pressure.
• This was attributed to an 800% increase in coronary vascular resistance.
• Cardiac output decreased significantly, while stroke volume remained largely unchanged.

Conclusions:

• Grey seal diving response effectively reduces cardiac workload and myocardial oxygen demand.
• The observed circulatory adjustments minimize myocardial blood flow without compromising cardiac function.
• Simulating these seal adaptations may offer novel treatments for human myocardial ischemia.