Maintained ability of carotid baroreflex to regulate arterial pressure during exercise

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Baroreceptor Function

Background:

• Arterial pressure regulation during exercise is complex.
• The roles of specific baroreceptors, such as carotid and aortic, are critical.
• Understanding these mechanisms is vital for cardiovascular health research.

Purpose of the Study:

• To investigate the role of the carotid baroreflex in modulating arterial pressure during rest and exercise.
• To examine the influence of vagotomy on baroreflex responses during physical activity.
• To determine the contribution of arterial and cardiopulmonary receptors to blood pressure support during exercise.

Main Methods:

• Bilateral carotid occlusion in conscious dogs at rest and during graded exercise.
• Analysis of arterial pressure and heart rate stimulus-response curves from isolated carotid sinuses.
• Assessment of responses after acute bilateral vagotomy.

Main Results:

• Carotid occlusion similarly increased arterial pressure at rest and during exercise.
• Carotid baroreflex curves shifted upward with exercise workload but maintained characteristics.
• Vagotomy altered baroreflex responses, with exercise curves displaced downward and leftward.
• Receptor denervation led to hypotension during mild exercise, with partial recovery during severe exercise.

Conclusions:

• The carotid baroreflex is effective in modulating arterial pressure during both rest and running.
• Arterial and cardiopulmonary baroreceptors play a significant role in supporting arterial pressure at the onset of exercise.