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Membrane currents controlled by physical forces in cultured mesangial cells
W Craelius1, M J Ross, D R Harris
1Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey.
Kidney International
|March 1, 1993
Summary
Mechanically-activated ion channels (MACs) in rat mesangial cells respond to physical forces like stretch and osmotic changes. These channels
Area of Science:
- Cell biology
- Biophysics
- Renal physiology
Background:
- Mechanically-activated ion channels (MACs) are crucial for cellular mechanotransduction.
- Understanding MACs in mesangial cells is vital for kidney function and disease research.
Purpose of the Study:
- To investigate the activation, kinetics, and ion selectivity of MACs in cultured rat mesangial cells.
- To determine the role of MACs in cellular responses to mechanical and osmotic stimuli.
Main Methods:
- Patch-clamp electrophysiology was used to record single-channel and whole-cell currents.
- Cells were subjected to mechanical stretch (suction) and osmotic gradients (hypoosmotic media).
- Membrane potential was manipulated to study MAC kinetic behavior.
Main Results:
- MACs were activated by both negative hydrostatic pressure and extracellular hypoosmolarity.
- MAC open probability increased with stretch and hypoosmolarity.
- Channel kinetics were sensitive to membrane potential, with depolarization increasing open time and hyperpolarization delaying inactivation.
- Ionic conductance was measured, with PK+/PNa+ estimated at 4.7; MACs did not significantly permeate chloride.
- Whole-cell currents showed ohmic behavior and were dependent on extracellular osmolarity.
Conclusions:
- MACs in rat mesangial cells are activated by physical forces, including stretch and osmotic gradients.
- MACs exhibit voltage-dependent gating kinetics.
- These findings suggest MACs play a role in mesangial cell responses to mechanical stress and osmotic challenges, potentially impacting renal function.