Читать книгу Canine and Feline Epilepsy - Luisa De Risio - Страница 42

The membrane after hyperpolarization that follows bursts of action potential discharge is the result, at least in part, of potassium currents activated by the entry of calcium and sodium. Increased calcium entry during the paroxysmal depolarizing shift, or as a result of the action of glutamate at the postsynaptic membrane, activates a calcium-dependent membrane potassium conductance that allows potassium efflux, membrane hyperpolarization and cessation of firing (Alger and Nicoll, 1980; Timofeev et al., 2004). Like calcium, sodium entry may also activate a sodium-dependent potassium current that reduces neuronal excitability by hyperpolarizing the membrane and increasing shunt conductance (Schwindt et al., 1989).