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Stable membrane potentials and mechanical K+ responses activated by internal Ca2+ in HeLa cells
Canadian Journal of Physiology and Pharmacology
|February 1, 1983
Summary
HeLa cell membrane potentials were measured, revealing a stable -38 mV average. A significant hyperpolarizing response, linked to increased potassium (K+) permeability, was observed following stimuli and could be modulated by calcium (Ca2+).
Area of Science:
- Cellular electrophysiology
- Ion channel function
Background:
- HeLa cells are a widely used human cancer cell line for biological research.
- Understanding membrane potential is crucial for cell function and signaling.
Purpose of the Study:
- To measure stable membrane potentials in HeLa cells.
- To investigate the mechanisms underlying hyperpolarizing responses in these cells.
Main Methods:
- Microelectrode impalement in HeLa cells to record membrane potentials.
- Application of mechanical and electrical shocks to induce cellular responses.
- Microinjection of calcium (Ca2+) and ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) to modulate ion permeability.
- Use of the Ca2+ ionophore A 23187.
Main Results:
- Average stable membrane potential in HeLa cells recorded at -38 mV, close to the chloride (Cl-) electrochemical potential (-34 mV).
- Observed a hyperpolarizing response upon microelectrode penetration and after mechanical or electrical shock.
- Demonstrated that this hyperpolarization is mediated by a significant increase in potassium (K+) permeability.
- Showed that Ca2+ injection triggers this K+ permeability increase, while EGTA injection blocks it.
- Achieved stable hyperpolarizations using the Ca2+ ionophore A 23187.
Conclusions:
- HeLa cell membrane potential is stable and near the Cl- equilibrium potential.
- Cellular shock or Ca2+ influx induces a robust K+ efflux mechanism, leading to hyperpolarization.
- This Ca2+-dependent K+ permeability is a key feature of HeLa cell electrophysiology.