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Preganglionic stimulation increases calcium uptake by sympathetic ganglia
Science (New York, N.Y.)
|April 23, 1971
Summary
Stimulating rat superior cervical ganglia increases calcium uptake, especially at higher frequencies. Magnesium ions reduce this extra calcium accumulation, suggesting a role in neuronal signaling.
Area of Science:
- Neuroscience
- Cellular Physiology
- Autonomic Nervous System Research
Background:
- The superior cervical ganglion (SCG) is a key component of the sympathetic nervous system.
- Calcium ions play a crucial role in neurotransmitter release and neuronal excitability.
- Understanding calcium dynamics in sympathetic ganglia is vital for comprehending autonomic functions.
Purpose of the Study:
- To investigate the effect of preganglionic stimulation on calcium accumulation in isolated rat SCG.
- To determine the influence of specific ions and blockers on stimulus-induced calcium uptake.
Main Methods:
- Isolated rat superior cervical ganglia were subjected to electrical preganglionic stimulation at varying frequencies (e.g., 12 impulses per second).
- Calcium-45 (a radioactive isotope of calcium) was used to quantify calcium uptake.
- The effects of magnesium, mecamylamine hydrochloride, and tetraethylammonium chloride on calcium uptake were assessed.
- High external potassium concentrations were used to evaluate calcium influx.
Main Results:
- Preganglionic stimulation significantly increased calcium-45 uptake in SCG compared to unstimulated controls.
- Calcium uptake approximately doubled with stimulation at 12 impulses per second.
- High magnesium concentrations markedly reduced the extra calcium uptake induced by stimulation.
- Mecamylamine hydrochloride and tetraethylammonium chloride did not reduce the extra calcium uptake, despite blocking the postsynaptic action potential.
- Elevated external potassium concentrations greatly enhanced calcium-45 uptake.
Conclusions:
- Neuronal activity in the SCG leads to increased intracellular calcium accumulation.
- Magnesium ions appear to modulate stimulus-induced calcium influx in the SCG.
- The observed calcium uptake mechanism is distinct from the receptors blocked by mecamylamine hydrochloride and tetraethylammonium chloride.
- Potassium-induced calcium influx highlights the dependence of calcium dynamics on ion gradients.
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