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Synaptic transmission in rat cardiac neurones
1Department of Autonomic Nervous System Physiology, A.A. Bogomoletz Institute of Physiology, Kiev, Ukraine.
Journal of the Autonomic Nervous System
|July 1, 1992
Summary
Rat cardiac neurons receive strong cholinergic inputs, generating excitatory postsynaptic potentials (EPSPs) with spikes. These EPSPs show resistance to ganglion blockers and are modulated by stimulation frequency.
Area of Science:
- Neuroscience
- Cardiac Electrophysiology
- Autonomic Nervous System Research
Background:
- Cardiac ganglia contain neurons that regulate heart function.
- Understanding synaptic transmission in cardiac neurons is crucial for cardiac control.
Purpose of the Study:
- To investigate synaptic transmission in rat cardiac neurons from the left atrium and interatrial septum.
- To characterize the nature and modulation of excitatory postsynaptic potentials (EPSPs) in these neurons.
Main Methods:
- Intracellular recordings from isolated rat cardiac ganglia.
- Stimulation of afferent fiber tracts.
- Pharmacological manipulation using Ca(2+)-free/high-Mg2+ solutions, neostigmine, hexamethonium, d-tubocurarine, and trimetaphan.
Main Results:
- Spontaneous and evoked excitatory postsynaptic potentials (EPSPs) were recorded.
- Evoked EPSPs were orthodromic, exaggerated by neostigmine, and attenuated at high frequencies.
- Ganglion-blocking agents showed differential effects on single vs. high-frequency stimulation responses.
Conclusions:
- Rat cardiac neurons receive strong, single cholinergic inputs eliciting EPSPs with spikes.
- These cardiac EPSPs are resistant to some ganglion blockers but modulated by stimulation frequency.
- Cardiac neurons exhibit high excitability with short after-hyperpolarization and repetitive firing properties.