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Firing patterns and synchronization in nonsynaptic epileptiform activity: the effect of gap junctions modulated by potassium accumulation.
Santos, D O C; Rodrigues, A M; de Almeida, A C G; Dickman, R.
Afiliação
  • Santos DO; Department of Physics, Federal University of Minas Gerais, Brazil. docs@fisica.ufmg.br
Phys Biol ; 6(4): 046019, 2009 Nov 26.
Article em En | MEDLINE | ID: mdl-19940352
Several lines of evidence point to the modification of firing patterns and of synchronization due to gap junctions (GJs) as having a role in the establishment of epileptiform activity (EA). However, previous studies consider GJs as ohmic resistors, ignoring the effects of intense variations in ionic concentration known to occur during seizures. In addition to GJs, extracellular potassium is regarded as a further important factor involved in seizure initiation and sustainment. To analyze how these two mechanisms act together to shape firing and synchronization, we use a detailed computational model for in vitro high-K(+) and low-Ca(2+) nonsynaptic EA. The model permits us to explore the modulation of electrotonic interactions under ionic concentration changes caused by electrodiffusion in the extracellular space, altered by tortuosity. In addition, we investigate the special case of null GJ current. Increased electrotonic interaction alters bursts and action potential frequencies, favoring synchronization. The particularities of pattern changes depend on the tortuosity and array size. Extracellular potassium accumulation alone modifies firing and synchronization when the GJ coupling is null.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Potássio / Junções Comunicantes / Epilepsia Tipo de estudo: Prognostic_studies Limite: Animals Idioma: En Ano de publicação: 2009 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Potássio / Junções Comunicantes / Epilepsia Tipo de estudo: Prognostic_studies Limite: Animals Idioma: En Ano de publicação: 2009 Tipo de documento: Article