Mechanosensitive single channel calcium currents in rat mesangial cells

Area of Science:

• Cellular Physiology
• Renal Cell Biology
• Ion Channel Research

Background:

• Mechanical stimulation of mesangial cells influences protooncogene expression, suggesting a role for mechanosensitive ion channels.
• Previous research indicated a potential mechanosensitive calcium (Ca2+) channel in mesangial cells, but its properties remained largely uncharacterized.

Purpose of the Study:

• To investigate the presence and properties of single channel Ca2+ currents in rat mesangial cells.
• To characterize a potential mechanosensitive Ca2+ channel responsive to mechanical stretch and osmotic pressure.

Main Methods:

• Utilized the patch-clamp technique on cell-attached patches of early passage rat mesangial cells.
• Employed 100 mM BaCl2 in patch-clamp pipets to study cation currents.
• Applied mechanical stretch via the patch pipet and altered extracellular osmolarity to assess channel activation.

Main Results:

• Identified a 21 pS, cobalt (Co2+)-sensitive cation channel in rat mesangial cells.
• Observed increased open probability of this channel upon mechanical stretch and reduced extracellular osmolarity.
• Documented spontaneous adaptation of channel responses despite continuous stimulation.

Conclusions:

• A novel mechanosensitive Ca2+ channel exists in rat mesangial cells, activated by mechanical stretch and osmotic changes.
• This channel exhibits unique electrophysiological and kinetic properties distinct from previously reported cation channels.
• The findings provide new insights into the mechanisms of mechanotransduction in renal mesangial cells.