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Mechanisms of baroreceptor activation
M W Chapleau1, G Hajduczok, R V Sharma
1Department of Internal Medicine, University of Iowa, Iowa City, U.S.A.
Clinical and Experimental Hypertension (New York, N.Y. : 1993)
|January 1, 1995
Summary
Baroreceptor activity (BRA) is modulated by paracrine factors and ionic mechanisms. Transient potassium channels and gadolinium-sensitive channels influence BRA adaptation and mechano-electrical transduction, respectively.
Area of Science:
- Cardiovascular physiology
- Neuroscience
- Cellular signaling
Background:
- Baroreceptors are crucial for regulating blood pressure.
- Understanding the factors influencing baroreceptor activity (BRA) is essential for cardiovascular control.
- The precise mechanisms of baroreceptor adaptation and mechano-electrical transduction are not fully elucidated.
Purpose of the Study:
- To investigate the determinants of nerve activity at baroreceptor endings.
- To explore the role of paracrine factors, ionic channels, and mechano-electrical transduction in baroreceptor function.
Main Methods:
- Experiments were conducted on isolated carotid sinus and nodose ganglion neurons.
- Baroreceptor activity was measured in response to various stimuli.
- Intracellular calcium changes were monitored using fura-2.
- Pharmacological agents like 4-aminopyridine and gadolinium were used.
Main Results:
- Activated endothelial cells and paracrine factors (endothelin, NO, PGI2) reversibly modulated BRA.
- Sustained non-pulsatile pressure increases led to BRA adaptation, attenuated by 4-aminopyridine.
- Gadolinium blocked BRA and increased intracellular calcium in neurons, suggesting a role for stretch-activated channels.
Conclusions:
- Paracrine factors significantly modulate baroreceptor sensitivity.
- Transient potassium channels (IA) are involved in baroreceptor adaptation to elevated pressure.
- Gadolinium-sensitive stretch-activated channels may act as mechano-electrical transducers in baroreceptor neurons.