THE EARLY IRREVERSIBLE CHANGES IN RABBITS LENS EPITHELIAL CELLS INDUCED BY Low POWER DENSITY MICROWAVE RADIATION AND IT

It is well established that various factors can induce cataract formation including microwave radiation. A resurgence of interest and concern with regard to the biologic effects and potential hazards of exposure to microwaves has been awoken. Since the environmental exposure to microwave radiation usually belongs to low doses, until 1998 lOmW/cm was recommended as the exposure limit, hi 1998, International Non-Ionizing Radiation Committee (INIRC) developed guidelines for limiting microwave exposure to eyes-5mW/cm2. Both of them are not the final exact health standard. Even now, the exact nature of the biological effects of microwave is not completely elucidated and understood, and leads to many answered questions: Whether exposure to microwave radiation under the power densities of 10mW/cm2 or 5mW/cm2 is really safe? Will they cause the early irreversible damage to lens? What are the mechanisms of the effect of the low dose microwave radiation.In our study, rabbits were exposed to microwave radiation with thepower densities of 5mW/cm2 and 10mW/cm2. We tried to verify the safety of limiting exposure guidelines and investigate the mechanisms of microwave's damage to lens that had become cataractogenous. By using transmission electron microscope (TEM), flow cytometry and laser-scanning microscope, we detected the characteristic ultrastructural morphologic changes and the early apoptosis of the lens epithelial cells (LECs) on the level of cell, hi order to further investigate on the molecular level and from another different view, we used the laser-scanning confocal microscope to examine the gap-junctional communication (GJIC) between rabbits LECs after irradiation. The observation suggested that GJIC was inhibited by the microwave radiation due to the dispersed and altered localization of gap-junction protein Connexin43.Our data indicated that both 5mW/cm2 and 10mW/cm2 power densities microwave radiation induced irreversible damage to rabbits' LECs on the cellular and molecular level. This may lead to losing of the normal function of LECs and the osmotic balance within lens. Thus it is plausible that impaired lens transparency subsequently occurred. No sever thermal damage changes were detected of the tissue and cells. We believe that this was the "non-thermal effect" of the low power density microwave. The safety of these two standards is to be questioned.PARTIThe Early Ultrastructural Changes of Rabbits LensEpithelial Cells Induced by Low Power DensityMicrowave RadiationObjective: Morphological assessment has been the most reliable method for identification of individual damage cell. In this part, we try to study the ultrastructural change of rabbits LECs with transmission electronmicroscope and to observe whether low power density microwave radiation will induce the injury of rabbits' lens.Methods: 1. Animal preparation: 16 health rabbits were selected randomly. They were assigned to two groups, one group (8 rabbits) was radiated with a power density of 5mW/cm2, the other group (8 rabbits) with 10mW/cm2. One eye of served as experimental eye, while the corresponding partner eye served as self-control.2. Specimen Preparation: Lens capsules with their adhering epithelium were obtained. They were made into grids and examined hi a JEM 1200EX transmission electron microscope.Results: Comparing to the normal controlled eyes' LECs, apparent ultrastructural changes were found in the size of cells, mitochondria and endoplasmic reticulum. In the group radiated with 5mW/cm2, the cell size is normal. Some of the mitochondria became swelling, the double-layer membrane and the intermembrane were disrupted. We could also observe damaged intermambrane debris hi mitochondria. In the other group radiated with 10mW/cm2, the cell size was shrunk. The number of mitochondria decreased, all of the mitochondria became vacuolarized and few of the intermembrane debris can be found. The endoplasmic reticulum was dilated obviously, which could not be observed in the cells of normal control ey...