Membrane Permeability Changes in Gamma‐irradiated Muscle Cells a

Gamma irradiation of the cell is the result of exposure to electromagnetic fields of frequencies 15-20 orders of magnitude greater than those in electric fields that cause the familiar high-voltage electrical injury. The resulting energy of this radiation is great enough that ionization of exposed molecules is possible. Research suggests that a t least two important mechanisms of cell damage from gamma irradiation are the result of changes in molecular structure-one affecting cell replicative and transcriptional mechanisms' and the other causing changes to the cell membrane.2,3 In the first mechanism, direct disruption of covalent bonds in nuclear DNA leading to chromosomal damage prevents effective cell replication in mitosis.' Changes in mRNA transcription may also occur, interfering with the manufacture of important cell proteins. The second proposed mechanism involves the formation of highly reactive free radicals secondary to ionizing radiation. These free radicals may directly affect the phospholipids of the cell membrane lipid bilayer,2 leading to changes in cell membrane permeability that disrupt important electrochemical control mechanisms of the membrane that are necessary for cell s ~ r v i v a l . ~ Experiments in our lab have focused on quantifying changes in lipid membrane permeability using microfluorescent techniques in postmitotic cells exposed to high-dose gamma irradiation. Our goal has been to more clearly demonstrate the kinetics of cell membrane changes in gamma irradiation to provide a basis for modeling the mechanisms of these changes and to test various chemical interventions to reduce membrane disruption secondary to gamma irradiation.