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Results for “Excitatory Postsynaptic Potentials”

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At least 73 records · Page 4Linked to original sources
PubMed1984

Neuromuscular transmission in the visceral muscle of locust oviduct.

Innervation of the locust oviduct has been investigated with morphological and electrophysiological methods. Using Co2+ and Ni2+ labelling technique, it was found that G7 N2B1 and B2a nerves innervate the oviduct musculature. Ultrastructurally two different terminals could be distinguished: (a) nerve endings containing mainly clear vesicles forming neuromuscular junctions with the muscle fibers; and (b) nerve terminals containing electron-dense granules which showed only "synaptoid" structures, but failed to form junctions with the muscle cells. The neuromuscular junctions proved to be functioning, since it was possible to record intracellularly miniature excitatory postsynaptic potentials and excitatory postsynaptic potentials from the muscle cells. The distribution of the amplitudes of the miniature excitatory postsynaptic potentials suggests a multiterminal innervation. Following electrical stimulation of N2B nerve, excitatory postsynaptic potentials similar to those appearing spontaneously could be evoked. After repetitive stimulation, facilitation or summation of excitatory postsynaptic potentials was observed. The results obtained show that locust oviduct muscle has a double, motor and modulatory innervation.

Animals↗
PubMed1991

Short-latency excitatory postsynaptic potentials are evoked in primate spinothalamic tract neurons by corticospinal tract volleys.

The responses of 8 wide-dynamic-range (WDR) STT neurons to electrical stimulation of the sensorimotor cortex or the cerebral peduncle were recorded intracellularly in anesthetized monkeys. EPSPs and spikes were evoked in STT neurons with short latencies ranging from 0.4 to 5.3 msec after the corticospinal volley, indicating a monosynaptic connection in at least some STT neurons. Spatial and temporal summation seem necessary for the cortex to maintain an effective excitatory influence on STT neurons. It is postulated that the cortical facilitation of STT neurons helps them to acquire more nociceptive signals during behavioral tasks such as exploring a new object so that the brain can make decisions about whether to continue or to abandon a certain task. Possible implications for central pain states are discussed.

Animals↗
PubMed1987

Neurokinin A in capsaicin-sensitive neurons of the guinea-pig inferior mesenteric ganglia: an additional putative mediator for the non-cholinergic excitatory postsynaptic potential.

The presence of neurokinin-A-like immunoreactivity in guinea-pig inferior mesenteric ganglia was detected by radioimmunoassay procedures. Pretreating the animals with capsaicin 7 days prior to experimentations reduced the mean content of neurokinin-A-like immunoreactivity by 85% from its control value of 150 +/- 31.3 fmol per ganglion. High-performance liquid chromatography revealed that neurokinin-A-like immunoreactivity was heterogenous as in addition to neurokinin A, peaks corresponding to the amphibian tachykinin eledoisin and to neuropeptide K were detected, and they too were depleted by capsaicin. Electrophysiological studies showed that neurokinin A applied either by superfusion or by pressure ejection evoked a slow depolarization in the majority of inferior mesenteric ganglia neurons in vitro. Neurokinin-A-evoked depolarizations in the majority of cells tested were associated with a small increase in membrane input resistance. However, the responses were increased by membrane hyperpolarization: the extrapolated mean equilibrium potential of neurokinin-A-induced depolarization was -36 mV. Removal of extracellular sodium but not chloride ions suppressed the neurokinin-A-induced depolarization. The slow depolarization elicited either by exogenously applied substance P or by repetitive stimulation of hypogastric nerves was reversibly eliminated in the presence of neurokinin A. Collectively, our studies suggest that neurokinin-A-like immunoreactivity may coexist with substance-P-like immunoreactivity in capsaicin-sensitive fibers in the guinea-pig prevertebral ganglia and that the similarity of the actions of neurokinin A on the one hand and substance P on the other raises the possibility that non-cholinergic excitatory potentials elicited in the inferior mesenteric ganglia may be generated by not one but a number of closely related tachykinins.

Animals↗
PubMed1988

A novel muscarinic receptor antagonist AF-DX 116 differentially blocks slow inhibitory and slow excitatory postsynaptic potentials in the rabbit sympathetic ganglia.

Muscarinic, slow postsynaptic potentials (s-epsp and s-ipsp) in the rabbit superior cervical ganglia were shown to be differentially depressed by a novel cardioselective M2-type antagonist AF-DX 116: it antagonized the s-ipsp with IC50 value of 1.5 X 10(-7) M, which is 16-fold more potent in depressing the s-ipsp than the s-epsp. A hyperpolarizing component in the biphasic potential changes induced by a muscarinic agonist, methacholine, was selectively eliminated by this antagonist. AF-DX 116 was thus shown to be an useful tool for discriminating the M2-type muscarinic responses from those of M1-type in the nervous system.

Action Potentials↗
PubMed1970

Excitatory postsynaptic potential and monosynaptic reflex discharge of spinal motoneurons during anoxic insult.

Almost universally held is the concept that in transmission from one neuron to another the so-called postsynaptic potential is the essential step leading to discharge of the secondary neurons. According to the present experiments this is not so in the monosynaptic reflex system of the cat spinal cord. Its role in facilitation of response and certain other essential data are mentioned.

Animals↗