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Modulation of neuronal function by intracellular pH
K I Takahashi1, D R Copenhagen
1Division of Biological Sciences, Faculty of Commercial Sciences, Hiroshima Shudo University, Japan. takahasi@shudo-u.ac.jp
Neuroscience Research
|January 1, 1996
Summary
Intracellular hydrogen ions (H+) act as neuromodulators, influencing neuronal excitability by altering ionic channel activity. This study demonstrates how changes in intracellular pH impact key ion currents in catfish retinal neurons.
Area of Science:
- Neuroscience
- Cellular Physiology
- Biochemistry
Background:
- Neuronal activity can induce localized pH changes in nervous tissue.
- Changes in intracellular pH (pHi) are known to affect neuronal excitability.
- Specific neurotransmitter receptor activations influence extracellular pH (pHo) and pHi.
Purpose of the Study:
- To investigate the role of intracellular hydrogen ions (H+) as neuromodulatory factors.
- To determine how changes in pHi affect neuronal function and ionic channel activity.
- To test the hypothesis that intracellular H+ modulates neuronal excitability.
Main Methods:
- Enzymatic dissociation of horizontal cells from catfish retina.
- Recording of high-voltage-activated (HVA) Ca2+ currents, inward rectifier K+ currents, and hemi-gap junctional currents.
- Application of L-glutamate to assess its effect on HVA Ca2+ currents and intracellular H+ concentration.
Main Results:
- Intracellular H+ concentration was found to modulate HVA Ca2+ current, inward rectifier K+ current, and hemi-gap junctional current.
- L-glutamate was observed to suppress HVA Ca2+ current by increasing intracellular H+ concentration.
- These findings support the role of intracellular H+ in regulating neuronal excitability.
Conclusions:
- Intracellular H+ ions function as second messengers, modulating neuronal excitability.
- The activity of ionic channels is regulated by intracellular H+ concentration.
- This mechanism provides a novel understanding of neuromodulation in the nervous system.