Na inactivation

Valproic acid is a fatty acid derivative which is used for the management of absences and the control of generalized tonic-clonic seizures. Multiple mechanisms of action have been proposed. It prolongs Na+ inactivation which could explain its effectiveness against grand mal seizures. However also inhibition of T-Type Ca++ channels has been postulated. 

Voltage-gated Na channels The DDT group, pyrethroids, Sabadilla Indoxacarb Delayed Na inactivation (Na channel modulators) Na channel blocker... 

Other conformational changes have been investigated, which give the Na -inactivation pattern with changes in the rate constants a and/or b but not in the extent of inactivation in the first phase. These are ATP (0.15-1 mM) in the presence or absence of Na" " (a unaffected, b decreased), Mg (2 mM) with or without Na a unaffected, b increased) and Mg " " (2 mM) plus ATP (1-2 mM) (a decreased, b increased more than by Mg alone). The latter effect is typical for ATP since ADP (2 mM) antagonizes the Mg + effect [48]. Thus Mg " and MgATP in millimolar concentrations cause conformational changes, but these effects cannot yet be ascribed to a particular step in the reaction mechanism (Section 2). 

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