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Pericardial mechanoreceptors with phrenic afferents
1Department of Anesthesiology, Medical College of Wisconsin, Children's Hospital of Wisconsin, Milwaukee.
The American Journal of Physiology
|June 1, 1993
Summary
This study found mechanosensitive receptors in the dog pericardium innervated by the phrenic nerve. These receptors respond to mechanical stimuli, not chemical ones, and are located in the fibrous pericardial layer.
Area of Science:
- Cardiovascular Physiology
- Neuroscience
- Anatomy
Background:
- The pericardium's sensory innervation is not fully understood.
- Phrenic nerve afferents are known to innervate diaphragmatic and mediastinal structures.
Purpose of the Study:
- To investigate the existence, activation stimuli, distribution, and location of pericardial mechanoreceptors with phrenic nerve afferents in dogs.
- To characterize the response properties of these newly identified receptors.
Main Methods:
- Recording of afferent nerve activity from phrenic nerves in anesthetized dogs.
- Mechanical and chemical stimulation of the pericardium.
- Anatomical mapping of receptor distribution.
Main Results:
- Pericardial mechanoreceptors with phrenic afferents were identified in 15/18 (right side) and 12/18 (left side) dogs.
- Receptors were primarily located in the fibrous pericardium along the pericardiophrenic attachment, overlying atria and AV grooves.
- Receptors responded to mechanical stimuli, some with cardiac rhythm, others to lung inflation; no chemosensitivity to capsaicin, bradykinin, or saline was observed.
Conclusions:
- This study provides the first evidence of mechanosensitive pericardial receptors innervated by the phrenic nerve in dogs.
- These findings contribute to understanding the sensory innervation of the heart and surrounding structures.
- The identified receptors may play a role in cardiopulmonary reflexes.