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Published on: February 18, 2020
Fast axonal transport is modulated by altering trans-axolemmal calcium flux
A C Breuer1, M Bond, M B Atkinson
1Department of Brain and Vascular Research, Cleveland Clinic Foundation, Ohio.
Cell Calcium
|April 1, 1992
Summary
Calcium ions (Ca2+) directly control fast axonal transport (FAxT) speed. Manipulating Ca2+ levels rapidly alters transport rates, with retrograde transport being more sensitive, suggesting Ca2+ is a key regulator.
Area of Science:
- Neuroscience
- Cell Biology
- Biophysics
Background:
- Fast axonal transport (FAxT) is crucial for neuronal function.
- The molecular mechanisms regulating FAxT speed remain largely unknown.
- Calcium's role in modulating axonal transport requires elucidation.
Purpose of the Study:
- To investigate the direct effects of calcium on fast axonal transport (FAxT).
- To determine if calcium levels influence the speed and directionality of axonal transport.
- To explore the potential role of calcium channels and intracellular calcium stores in FAxT regulation.
Main Methods:
- Utilized video enhanced microscopy to directly observe and quantify FAxT in real-time.
- Manipulated extracellular and intracellular calcium levels using various agents (e.g., Ca2+-free buffer, parathyroid hormone, BAY K 8644, K+ depolarization, ryanodine, calcium ionophore A23187).
- Assessed the impact of pharmacological Ca2+ channel blockers and osmotic challenges on transport dynamics.
Main Results:
- Decreased FAxT speed observed in Ca2+-free conditions; rapid speed increases induced by agents increasing intracellular Ca2+.
- Speed increases were sensitive to dihydropyridine Ca2+ channel antagonists.
- Ryanodine and calcium ionophore A23187 affected retrograde transport, suggesting Ca2+ modulates transport directionality.
- Osmotic challenges did not alter transport, ruling out viscosity changes as the cause.
Conclusions:
- Direct evidence that calcium ions (Ca2+) modulate fast axonal transport (FAxT) speed.
- Retrograde transport exhibits higher sensitivity to Ca2+ fluctuations.
- Directional specificity in FAxT modulation suggests organelle-size-dependent mechanisms.
- Endogenous substances affecting axonal Ca2+ can rapidly regulate axonal transport and material delivery.
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Overview
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