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Store-operated Ca(2+) channels in human glomerular mesangial cells
1Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha 68198-4575, USA.
American Journal of Physiology. Renal Physiology
|June 3, 2000
Summary
Human glomerular mesangial cells (MC) possess store-operated calcium channels (SOC) crucial for calcium influx. These channels exhibit specific biophysical properties, indicating their role in cellular calcium regulation.
Area of Science:
- Nephrology
- Cell Physiology
- Ion Channel Biology
Background:
- Store-operated calcium channels (SOC) regulate intracellular calcium levels.
- Glomerular mesangial cells (MC) play a key role in kidney function.
- Understanding calcium signaling in MC is vital for kidney health.
Purpose of the Study:
- To identify the biophysical properties of SOC in cultured human MC.
- To characterize the ion selectivity and conductance of these channels.
- To determine the abundance and functional significance of SOC in MC.
Main Methods:
- Fluorometric technique (fura 2) to measure intracellular calcium changes.
- Thapsigargin treatment to deplete intracellular calcium stores.
- Patch-clamp electrophysiology to record single-channel currents.
Main Results:
- SOC activation led to significant calcium influx in MC.
- Single-channel analysis revealed low conductance and high selectivity for divalent cations (Ca2+ > Ba2+).
- SOC were sensitive to La3+ but not Cd2+, and were voltage-independent.
Conclusions:
- Human MC possess an electrogenic calcium influx pathway consistent with SOC.
- These SOC have low single-channel conductance and are abundant in MC.
- SOC are critical for capacitative calcium entry and cellular calcium homeostasis in MC.