Читать книгу Canine and Feline Epilepsy - Luisa De Risio - Страница 14

Both functional and structural alterations occur in epileptic foci. The functional changes involve concentrations of cations and anions, metabolic alterations, and changes in neuro-transmitter levels. The structural changes involve both neurons and glia. Excessive extracellular K+ depolarizes neurons and leads to spike discharge. During seizures, changes in extracellular Ca2+ (a decrease of 85%) precede those of K+ by milliseconds and Ca2+ levels return to normal more quickly than K+. Glia are able to clear neurotransmitters from the extracellular space and to buffer K+, thus correcting the increased extracellular K+ concentrations that occur during seizures. Epileptic foci may show proliferation of glia that differ however in morphological and physiological properties (Bordey and Sontheimer, 1998). Gliosis will affect glial K+ buffering capacity and hence may contribute to seizure generation.