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Norepinephrine inhibits calcium-dependent potentials in rat sympathetic neurons
Science (New York, N.Y.)
|June 15, 1979
Summary
Norepinephrine (NE) reversibly blocks calcium potentials in rat neurons. Alpha-adrenergic blockers antagonize this effect, suggesting NE may inhibit voltage-sensitive calcium currents via alpha-adrenergic receptors.
Area of Science:
- Neuroscience
- Pharmacology
- Cellular Electrophysiology
Background:
- Norepinephrine (NE) is a key neurotransmitter influencing neuronal excitability.
- Calcium-dependent potentials play crucial roles in neuronal function, including action potential generation and neurotransmitter release.
Purpose of the Study:
- To investigate the effects of norepinephrine on calcium-dependent potentials in rat postganglionic neurons.
- To determine the adrenergic receptor subtype involved in norepinephrine's action on these potentials.
Main Methods:
- Electrophysiological recordings from rat postganglionic neurons.
- Application of norepinephrine and adrenergic antagonists (phentolamine, MJ 1999).
- Analysis of action potential shoulder, hyperpolarizing afterpotential, and calcium spike characteristics.
Main Results:
- Norepinephrine reversibly antagonized three calcium-dependent potentials.
- Inhibition of action potential shoulder, hyperpolarizing afterpotential, and calcium spike rate of rise/amplitude.
- Alpha-adrenergic antagonist phentolamine blocked norepinephrine's action, while a beta-adrenergic antagonist did not.
Conclusions:
- Norepinephrine antagonizes calcium-dependent potentials in rat neurons.
- These effects are mediated via alpha-adrenergic receptors.
- Activation of alpha-adrenergic receptors likely antagonizes a voltage-sensitive calcium current.