A thermodynamic model describing multicomponent fluid membranes under the influence of lateral forces due to a buried charge is developed to estimate the magnitude and dynamics of field-induced lateral reorganization in membranes of living cells. The calculations were performed for an electric field geometry such as might be produced by a charge in an ion channel but can apply to any situation where charge is buried in the low dielectric environment of a membrane, for example, during electron transfer. The model includes molecular size and charge differences as well as critical demixing effects. These calculations indicate that the local concentration of charged and uncharged membrane components can be substantially altered over the course of a few microseconds. Critical demixing effects enhance the propensity of a membrane toward lateral reorganization and provide an intriguing mechanism by which an electric field can induce separation between neutral molecules such as cholesterol and phosphatidylcholine.