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Updated: Sep 21, 2026

Whole-Cell Recording of Calcium Release-Activated Calcium (CRAC) Currents in Human T Lymphocytes
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Published on: December 21, 2010

Sodium block and depolarization diminish P2Z-dependent Ca2+ entry in human B lymphocytes

M Löhn1, M Klapperstück, D Riemann

  • 1Franz-Volhard-Klinik am Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany.

Cell Calcium
|May 16, 2001
PubMed

Insights

Extracellular ATP has a minor effect on B lymphocyte calcium levels due to sodium influx. This study reveals that sodium influx, not calcium, is key to P2Z receptor signaling in B cells.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • The P2Z receptor in human B lymphocytes is highly permeable to calcium ions.
  • Extracellular ATP (adenosine triphosphate) has a limited impact on global intracellular calcium concentration ([Ca2+]i) in these cells.

Purpose of the Study:

  • To elucidate the mechanisms behind the discrepancy between P2Z receptor's Ca2+ permeability and its minor effect on [Ca2+]i.
  • To investigate the relationship between ATP application, calcium response, membrane current, and membrane potential in human B cells.

Main Methods:

  • Utilized FACS and voltage clamp techniques.
  • Employed voltage- and Ca2+-sensitive fluorescent dyes.
  • Tested responses in human B cell lines and primary tonsillar B cells.

Main Results:

  • ATP-induced changes in whole-cell current and [Ca2+]i were inhibited by both extracellular and intracellular sodium (Na+).
  • In current clamp conditions, Na+ influx reduced Ca2+ entry by decreasing the driving force.
  • Significant increases in [Ca2+]i were only observed in sodium-free solutions.

Conclusions:

  • Under physiological conditions, P2Z receptor signaling in B lymphocytes primarily involves membrane depolarization due to Na+ influx.
  • The pathway does not appear to operate via a substantial increase in global intracellular Ca2+ concentration.

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