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Activation of mechanosensitive currents in traumatized membrane
1Neurosciences, Loeb Health Research Institute, Ottawa Hospital, Ottawa, Ontario, Canada K1Y 4E9.
The American Journal of Physiology
|February 10, 1999
Summary
Mechanosensitive (MS) channels are protected by the cell cytoskeleton. Disrupting the cytoskeleton or altering cell volume can reveal these crucial channels, aiding in their study and understanding.
Area of Science:
- Cell Biology
- Biophysics
- Neuroscience
Background:
- Mechanosensitive (MS) channels respond to membrane tension but are often insensitive in their native cellular environment.
- This insensitivity suggests endogenous protective mechanisms limit their mechanical gating in situ.
Purpose of the Study:
- To investigate factors influencing the mechanosensitivity of MS channels.
- To understand the role of the cytoskeleton and cell volume in MS channel gating.
Main Methods:
- Monitoring Lymnaea neuron stretch-activated K+ (SAK) channels in cell-attached patches.
- Applying diverse treatments including actin depolymerization, ATPase inhibition, calcium elevation, and osmotic volume changes.
- Assessing mechanosensitivity by the speed and extent of channel activation under pressure.
Main Results:
- Actin depolymerization, ATPase inhibition, elevated intracellular Ca2+, and osmotic swelling significantly enhanced SAK channel mechanosensitivity.
- Osmotic shrinking reduced channel mechanosensitivity.
- Endogenous MS currents were detected in L-M(TK-) fibroblasts, challenging previous reports.
Conclusions:
- The cortical cytoskeleton plays a protective role, preventing mechanical stimuli from reaching MS channels.
- Modulating the cytoskeleton and cell volume are key to unmasking MS channel activity.
- These findings have implications for studying MS channels and their role in cellular function.