title: A cooperative model for Ca(++) efflux windowing from cell membranes exposed to electromagnetic radiation.
abstract: We propose a simplified version of a cooperative lattice membrane model given by Grodsky to explain observed Ca(++) efflux windowing effects from cell membranes exposed to electromagnetic radiation. Assuming that field induced conformational interactions occur only between bistable receptor sites and glycoprotein Ca(++) sites on the surface of the membrane, the model is shown to be equivalent to an Ising model. This model is known to have a phase transition to an ordered state in which a macroscopic number of Ca(++) sites are either occupied or unoccupied. We identify such states with enhanced Ca(++) efflux from cell membranes. By further assuming an averaged signal, sinusoidally varying coupling between receptor and Ca(++) sites and a power-law dependence of the characteristic time constant on the induced power-density of the applied field, we show that the model is consistent with published experimental results on power density windowing effects for particular values of model parameters. For these parameter values, the model predicts further power densities where windowing effects may be observed under appropriate conditions.
authors.affiliation: Department of Mathematics and Statistics, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: C J
authors.initials: CJ
authors.lastname: Thompson
authors.forename: Y S
authors.initials: YS
authors.lastname: Yang
authors.forename: V
authors.initials: V
authors.lastname: Anderson
authors.forename: A W
authors.initials: AW
authors.lastname: Wood
mesh_terms: D000465:Algorithms; D001665:Binding Sites / Q000528:radiation effects; D002118:Calcium / Q000528:radiation effects*; D020013:Calcium Signaling / Q000528:radiation effects; D002462:Cell Membrane / Q000528:radiation effects*; D004574:Electromagnetic Fields / Q000009:adverse effects; D006801:Humans; D008562:Membrane Glycoproteins / Q000528:radiation effects; D008954:Models, Biological; D008956:Models, Chemical; D011829:Radiation Dosage; D011956:Receptors, Cell Surface / Q000528:radiation effects
chemical_list: D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D002118:Calcium