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Stretch-inactivated cationic channels in single smooth muscle cells
T Hisada1, J V Walsh, J J Singer
1Department of Physiology, University of Massachusetts Medical Center, Worcester 01655.
Pflugers Archiv : European Journal of Physiology
|January 1, 1993
Summary
Stretch-inactivated channels (SICs) in toad stomach smooth muscle were identified. Negative pressure suppressed SIC activity, revealing cation permeability and outward rectification, crucial for understanding muscle function.
Area of Science:
- Physiology
- Cell Biology
- Biophysics
Background:
- Smooth muscle cells possess ion channels that regulate cellular function.
- Stretch-inactivated channels (SICs) are a class of mechanosensitive ion channels.
- Understanding SICs is vital for elucidating smooth muscle mechanotransduction.
Purpose of the Study:
- To identify and characterize stretch-inactivated channels (SICs) in toad stomach smooth muscle cells.
- To investigate the biophysical properties and gating mechanisms of SICs.
- To determine the ion permeability and conductance characteristics of SICs.
Main Methods:
- Isolation of single smooth muscle cells from the toad stomach (Bufo marinus).
- Electrophysiological recordings using cell-attached and excised inside-out patch-clamp techniques.
- Application of negative pressure to membrane patches to modulate channel activity.
Main Results:
- SICs were identified in toad stomach smooth muscle cells.
- Negative pressure on the extracellular membrane surface suppressed SIC activity.
- Channels exhibited cation permeability, outward rectification, and varying conductance based on divalent cation presence.
Conclusions:
- Stretch-inactivated channels are present in toad stomach smooth muscle.
- Mechanical forces regulate SIC activity, influencing ion flux.
- These findings contribute to the understanding of mechanosensitive channel function in smooth muscle physiology.