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Mechanosensitive ion channels in putative aortic baroreceptor neurons
S Kraske1, J T Cunningham, G Hajduczok
1Cardiovascular Center, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.
The American Journal of Physiology
|September 24, 1998
Summary
This study investigated mechanosensitive (MS) ion channels in rat aortic neurons. Co-culturing with endothelial cells increased MS channel expression, suggesting a secreted factor influences these crucial sensory channels.
Area of Science:
- Neuroscience
- Physiology
- Biophysics
Background:
- Mechanosensitive (MS) ion channels are crucial for sensing mechanical stimuli in neurons.
- Previous studies identified MS whole-cell currents in aortic baroreceptor neurons.
- The influence of culture conditions on single MS channel expression was not well understood.
Purpose of the Study:
- To investigate the properties of single mechanosensitive ion channels in rat aortic baroreceptor neurons.
- To examine the effect of co-culturing conditions on the expression of these MS ion channels.
- To identify potential factors influencing MS channel expression in these sensory neurons.
Main Methods:
- Cell-attached patch-clamp recordings were performed on dissociated rat nodose ganglia neurons.
- Putative aortic baroreceptor neurons were identified using DiI labeling.
- Single MS channels were activated by negative pressure, and their properties (conductance, reversal potential) were characterized.
- Neurons were co-cultured with aortic endothelial or smooth muscle cells to assess the influence of culture conditions.
Main Results:
- Single MS ion channels were identified with a slope conductance of 114 pS and a reversal potential near 0 mV, indicating non-specific cation permeability.
- Channel activity increased with negative pressure, with significant openings above 30 mmHg.
- The MS channels were insensitive to voltage-gated channel blockers but were inhibited by gadolinium.
- Co-culture with aortic endothelial cells, but not smooth muscle cells, significantly increased the percentage of patches exhibiting MS channels.
Conclusions:
- Aortic endothelial cells secrete a diffusible factor that enhances the expression of mechanosensitive ion channels in baroreceptor neurons.
- This finding suggests a novel mechanism by which endothelial cells modulate neuronal mechanosensitivity.
- Understanding this interaction could have implications for regulating blood pressure and cardiovascular reflexes.
Keywords:
Non-programmatic