Aortic Body Chemoreceptors Regulate Coronary Blood Flow in Conscious Control and Hypertensive Sheep

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System
• Renal Hypertension

Background:

• Peripheral arterial chemoreceptors, including aortic bodies (ABs), monitor blood chemistry.
• The physiological role of ABs, particularly in hypertension, is under-studied.
• Carotid bodies' function is well-researched, contrasting with the limited knowledge of ABs.

Purpose of the Study:

• To investigate the role of ABs in regulating coronary blood flow in normotensive and hypertensive states.
• To determine if parasympathetic nerves mediate the coronary blood flow response to AB activation.
• To examine alterations in AB-mediated coronary blood flow regulation in a renovascular hypertension model.

Main Methods:

• Experiments conducted in conscious and anesthetized ewes.
• Measurements included arterial pressure, coronary blood flow, and cardiac output.
• Two groups studied: hypertensive (2 kidney 1 clip model) and normotensive (sham-clipped).

Main Results:

• AB activation increased coronary blood flow in normotensive animals, partly via a cholinergic mechanism (atropine attenuated).
• AB activation also increased coronary blood flow in hypertensive animals, with no significant difference from normotensive.
• Coronary vasodilation in hypertensive animals was unaffected by muscarinic blockade but attenuated by propranolol.

Conclusions:

• Aortic bodies play a significant role in modulating coronary blood flow.
• The effector mechanism by which ABs influence coronary blood flow is altered in hypertension.
• These findings highlight a potential new pathway involved in hypertension pathophysiology.