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Brain stem area with C1 epinephrine neurons mediates baroreflex vasodepressor responses
The American Journal of Physiology
|April 1, 1985
Summary
Neurons in the rostral ventrolateral medulla (RVL), specifically the C1 epinephrine group, are crucial for regulating blood pressure and heart rate. Lesions here abolish reflex hypotension and bradycardia, indicating their vital role in cardiovascular control.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
Background:
- The rostral ventrolateral medulla (RVL) is implicated in cardiovascular regulation.
- Epinephrine neurons in the C1 group are a key component of the RVL.
Purpose of the Study:
- To investigate the role of C1 epinephrine neurons in the RVL in mediating cardiovascular reflexes.
- To determine the necessity of RVL C1 neurons for maintaining arterial pressure.
Main Methods:
- Bilateral electrolytic lesions of the RVL C1 area in anesthetized rats.
- Combined lesions of the nucleus tractus solitarii (NTS) and C1 area.
- Microinjection of kainic acid into the C1 area.
- Measurement of arterial pressure (AP) and heart rate (HR).
Main Results:
- RVL C1 lesions abolished reflex hypotension and bradycardia from vagal nerve stimulation or carotid sinus stretch.
- Lesions reduced AP and HR to levels seen after spinal cord transection.
- Combined NTS and C1 lesions abolished vasodepressor reflexes, suggesting a pathway involving NTS-RVL projection.
Conclusions:
- RVL neurons, likely C1 epinephrine neurons, mediate vasodepressor responses from baro- and cardiopulmonary receptors.
- A direct NTS-RVL projection may be involved in this pathway.
- C1 area neurons are essential for maintaining resting arterial pressure.