Voltage-gated calcium currents in mouse spinal motoneurones, possible role in plateau potentials
Notice bibliographique
Résumé
Intracellular studies of the spinal motoneurones in the adult in-vivo cat identified a slowly activating persistent inward current that could be activated by brief depolarizations. The presence of this current provided these cells with two stable membrane potentials--one at the resting potential and the other at a more depolarized potential. Because this second potential is above threshold for sodium spikes, cells will fire repetitively at this second stable membrane potential. If the sodium spikes are blocked, the underlying sustained depolarization can be seen--this stable depolarization resulting from a brief depolarizing stimulus is termed a plateau potential. The ionic nature of the persistent inward current was difficult to determine in the in-vivo cat. Researchers therefore turned to in-vitro preparations in order to study this current. Due to the difficulties associated with maintaining viable mammalian spinal cord tissue in-vitro, this current was studied in adult turtle spinal motoneurones which are more tolerant of in-vitro conditions. Using this preparation it was determined that the persistent inward current was mediated by a subtype of voltagegated calcium channels termed L-type channels. Furthermore, it was determined that these channels were located in the dendrites of these cells. Plateau potentials have since been demonstrated in a number of different cell types in both vertebrate and invertebrate nervous systems. A number of different underlying conductances have been shown to mediate the plateaux in these different cell types. The ionic nature of the current mediating plateau potentials has not been determined in mammalian spinal motoneurones. The purpose of this thesis was to examine the nature of this current. Specifically, this thesis tested the hypothesis that mammalian spinal motoneurones use L-type voltage-gated calcium channels in the production of plateau potentials. Using an in-vitro spinal cord slice preparation and whole cell patch clamp recording techniques, voltage-gated calcium currents were characterized in mouse lumbar spinal motoneurones. These experiments demonstrated, for the first time, the presence of a variety of channel subtypes including: T-, N-, P/Q- and R-type channels. Of particular interest was the presence of a dihydropyridinesensitive L-type current. In a second set of experiments it was demonstrated that a subpopulation of the L-type calcium channels were located in the dendrites of these motoneurones. This result is consistent with the location of L-type channels responsible for plateau potentials in turtle spinal motoneurones. The final set of experiments demonstrated plateau potentials in mouse spinal motoneurones. These plateaux are calcium-mediated and can be elicited by activation of L-type calcium channels.The demonstration that mammalian spinal motoneurones express L-type channels, a portion of which are located in a subcellular location consistent with their role in the generation of plateau potentials, suggests that mammalian spinal motoneurones use the same ionic mechanisms to generate platea potentials as do lower species like the turtle. Furthermore, this idea is supported by the ability of L-type calcium channel activators to elicit plateaux in mammalian spinal motoneurones.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».