Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 8183184

Nerve conduction velocity decrease and synaptic transmission alterations in caffeine-treated rats.

A Raya·A M Cuervo·F Macián·F J Romero·J Romá
View original source ↗Export metadata ↓

Abstract

The action of caffeine on peripheral neuromuscular function was studied by means of in vivo determinations of electrophysiological parameters, i.e., amplitude of extracellularly recorded muscle action potentials and nerve conduction velocity in the dorsal skeletal muscle and caudal nerve of the rat tail, respectively. Repeated exposure of the rats was carried out by adding caffeine to the drinking water for 10 days. Here we report the novel finding that motor nerve conduction velocity showed a significant decrease in caffeine-treated animals, whereas no change was observed in the amplitude of indirectly evoked extracellular muscle action potentials. The physiological recovery of the amplitude of the compound muscle action potential observed in nonintoxicated rats after high-frequency stimulation (10 Hz) was not observed in intoxicated animals and is also discussed.

Explore related subjects

Action PotentialsAnimalsBody WeightCaffeineElectric StimulationElectrophysiologyMaleMotor NeuronsMusclesNeural ConductionRatsRats, WistarSynapsesSynaptic TransmissionJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

A Raya, A M Cuervo, F Macián, F J Romero, J Romá. Nerve conduction velocity decrease and synaptic transmission alterations in caffeine-treated rats.. https://doi.org/10.1016/0892-0362(94)90003-5

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1996

Axonal action-potential initiation and Na+ channel densities in the soma and axon initial segment of subicular pyramidal neurons.

A long-standing hypothesis is that action potentials initiate first in the axon hillock/initial segment (AH-IS) region because of a locally high density of Na+ channels. We tested this idea in subicular pyramidal neurons by using patch-clamp recordings in hippocampal slices. Simultaneous recordings from the soma and IS confirmed that orthodromic action potentials initiated in the axon and then invaded the soma. However, blocking Na+ channels in the AH-IS with locally applied tetrodotoxin (TTX) did not raise the somatic threshold membrane potential for orthodromic spikes. TTX applied to the axon beyond the AH-IS (30-60 microm from the soma) raised the apparent somatic threshold by approximately 8 mV. We estimated the Na+ current density in the AH-IS and somatic membranes by using cell-attached patch-clamp recordings and found similar magnitudes (3-4 pA/microm2). Thus, the present results suggest that orthodromic action potentials initiate in the axon beyond the AH-IS and that the minimum threshold for spike initiation of the neuron is not determined by a high density of Na+ channels in the AH-IS region.

Action Potentials↗
PubMed1996

Neural control of voluntary movement initiation.

When humans respond to sensory stimulation, their reaction times tend to be long and variable relative to neural transduction and transmission times. The neural processes responsible for the duration and variability of reaction times are not understood. Single-cell recordings in a motor area of the cerebral cortex in behaving rhesus monkeys (Macaca mulatta) were used to evaluate two alternative mathematical models of the processes that underlie reaction times. Movements were initiated if and only if the neural activity reached a specific and constant threshold activation level. Stochastic variability in the rate at which neural activity grew toward that threshold resulted in the distribution of reaction times. This finding elucidates a specific link between motor behavior and activation of neurons in the cerebral cortex.

Action Potentials↗
PubMed1996

Chattering cells: superficial pyramidal neurons contributing to the generation of synchronous oscillations in the visual cortex.

In response to visual stimulation, a subset of neurons in the striate and prestriate cortex displays synchronous rhythmic firing in the gamma frequency band (20 to 70 hertz). This finding has raised two fundamental questions: What is the functional significance of synchronous gamma-band activity and how is it generated? This report addresses the second of these two questions. By means of intracellular recording and staining of single cells in the cat striate cortex in vivo, a biophysically distinct class of pyramidal neuron termed "chattering cells" is described. These neurons are located in the superficial layers of the cortex, intrinsically generate 20- to 70-hertz repetitive burst firing in response to suprathreshold depolarizing current injection, and exhibit pronounced oscillations in membrane potential during visual stimulation that are largely absent during periods of spontaneous activity. These properties suggest that chattering cells may make a substantial intracortical contribution to the generation of synchronous cortical oscillations and thus participate in the recruitment of large populations of cells into synchronously firing assemblies.

Action Potentials↗