Facilitation of N-type calcium current is dependent on the frequency of action potential-like depolarizations in dissociated cholinergic basal forebrain neurons of the guinea pig

Autor: Laurent Bernheim, Mauro Serafin, Sylvain Williams, Michel Muhlethaler
Jazyk: angličtina
Rok vydání: 1997
Předmět:
Calcium/ metabolism
Acetylcholine/ physiology
Choline O-Acetyltransferase/analysis
Guinea Pigs
GTPgammaS
chemistry.chemical_element
Action Potentials
Nerve Tissue Proteins
Biology
Calcium
Basal Ganglia
Choline O-Acetyltransferase
chemistry.chemical_compound
GTP-Binding Proteins
medicine
Animals
Basal Ganglia/ cytology
Ethylmaleimide/pharmacology
Calcium Channels/classification/ metabolism
Neurons
Neurotransmitter Agents
Basal forebrain
Voltage-dependent calcium channel
General Neuroscience
Neurons/ physiology
Depolarization
Neurotransmitter Agents/physiology
Articles
Acetylcholine
ddc:616.8
chemistry
Nerve Tissue Proteins/analysis
Ethylmaleimide
Guanosine 5'-O-(3-Thiotriphosphate)
Disinhibition
Facilitation
Cholinergic
Calcium Channels
GTP-Binding Proteins/metabolism
medicine.symptom
Neuroscience
Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
Zdroj: Journal of Neuroscience, Vol. 17, No 5 (1997) pp. 1625-1632
ISSN: 0270-6474
Popis: Voltage-dependent inhibition of high voltage-activated (HVA) calcium currents by G-proteins can be transiently relieved (facilitated) by strong depolarizing prepulses. However, with respect to the physiological significance of facilitation, it remains to be established if it can be induced by action potentials (AP) in central neurons. With the use of whole-cell recordings of dissociated cholinergic basal forebrain neurons of the guinea pig, it is shown that the GTPγS-inhibited HVA currents that occur throughN-ethylmaleimide (NEM)-sensitive Gi–Gosubtypes of G-proteins can be facilitated. Furthermore, although different types of HVA channels are present in these neurons, facilitation occurred mostly through disinhibition of the N-type current. On the basis of data indicating that the recovery from facilitation was relatively slow, we tested if more physiological stimuli that crudely mimicked APs (2 msec long depolarizations to 40 mV from a holding of −50 mV) potentially could induce facilitation of HVA currents inhibited by GTPγS and cholinergic agonists. Indeed, evidence is provided that the extent of facilitation is dependent on both the number and frequency of AP-like depolarizations. These results suggest that firing rates and patterns of discharge of neurons could influence their responsiveness to transmitters acting on N-type HVA calcium channels.
Databáze: OpenAIRE
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