Enhanced neuronal excitability in adult rat brainstem causes widespread repetitive brainstem depolarizations with cardiovascular consequences.
J Cereb Blood Flow Metab
; 32(8): 1535-45, 2012 Aug.
Article
en En
| MEDLINE
| ID: mdl-22453631
ABSTRACT
The brainstem of the adult rat is relatively resistant to spreading depolarization (SD) but after enhancement of excitability SD can be evoked by local application of KCl. In the present experiments, we observed that the enhanced excitability even triggers prolonged periods of repetitive depolarizations (RDs), which elicit significant cardiovascular changes. In contrast to KCl-evoked SDs with amplitudes of â¼24 mV and spreading velocity of 4 mm/min, spontaneous RDs had amplitudes of 7 to 12 mV, propagated up to 30 times faster than KCl-evoked SDs, and depolarized larger brainstem areas including the contralateral side. Similarly as SD, RDs depended on glutamatergic neurotransmission and were blocked by MK-801 or by the calcium channel blocker agatoxin. They depended on sodium channels and were blocked by tetrodotoxin. Functionally, the invasion of RDs into the spinal trigeminal and other nuclei evoked bursts of action potentials, indicating that specific neuronal systems are affected. In fact, during episodes of RDs the blood pressure and the local blood flow at the surface of the brainstem and the cortex increased substantially. Brainstem RDs did not propagate into the cerebral cortex. We propose to consider brainstem RPs as a pathophysiological mechanism whose significance for brainstem disease states should be further explored.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Depresión de Propagación Cortical
/
Presión Sanguínea
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Tronco Encefálico
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Frecuencia Cardíaca
/
Neuronas
Tipo de estudio:
Etiology_studies
Límite:
Animals
Idioma:
En
Revista:
J Cereb Blood Flow Metab
Año:
2012
Tipo del documento:
Article
País de afiliación:
Alemania