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Published on: July 3, 2013
A voltage-activated proton current in human cardiac fibroblasts
Antoun El Chemaly1, Romain Guinamard, Marie Demion
1Institut de Physiologie et Biologie Cellulaires, UMR CNRS 6187, Université de Poitiers, 40 avenue du Recteur Pineau 86022 Poitiers Cedex, France.
Biochemical and Biophysical Research Communications
|December 27, 2005
Summary
A novel voltage-activated proton current in human cardiac fibroblasts was identified. This proton current plays a role in regulating intracellular pH and membrane potential, particularly during acidosis and ischemia.
Area of Science:
- Cardiology
- Cell Physiology
- Biophysics
Background:
- Human cardiac fibroblasts play crucial roles in cardiac tissue structure and function.
- Intracellular pH (pHi) regulation is vital for cardiac cell viability and function.
- Dysregulation of pH homeostasis is implicated in cardiac pathologies like ischemia.
Purpose of the Study:
- To characterize a voltage-activated proton current in human cardiac fibroblasts.
- To investigate the biophysical properties and ion selectivity of this proton current.
- To determine the potential physiological and pathological roles of this current in cardiac fibroblasts.
Main Methods:
- Whole-cell patch-clamp technique was employed to record ionic currents.
- Variations in extracellular pH were used to probe current properties.
- Proton selectivity was assessed by analyzing reversal potential shifts.
- The effect of zinc ions (Zn2+) on the current was examined.
Main Results:
- A voltage-activated proton current was identified in human cardiac fibroblasts.
- Increasing extracellular pH shifted activation to more negative potentials and increased current amplitude and activation rate.
- A one-unit pH gradient shift caused a 51mV shift in reversal potential, indicating high proton selectivity.
- Extracellular Zn2+ reversibly inhibited the proton current.
- This current contributes to resting membrane conductance during intracellular acidosis.
Conclusions:
- Human cardiac fibroblasts possess a voltage-activated proton channel.
- This channel exhibits high selectivity for protons and is modulated by extracellular pH and Zn2+.
- The identified proton current is likely involved in regulating intracellular pH and membrane potential in cardiac fibroblasts under physiological and pathological conditions, including ischemia.
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