Effects of Modulated and Continuous Microwave Irradiation on Pyroantimonate Precipitable Calcium Content in Junctional Complex of Mouse Small Intestine

The pyroantimonate precipitable calcium content of intestinal epithelial cells was investigated in mice following total body irradiation with 2450 MHz continuous and low frequency (16 Hz) square modulated waves. In the control animals the reaction products appeared in the intercellular space of adjacent cells including intermediate junctions and desmosomes and were absent in the area of tight junctions. Immediately after low frequency modulated microwave irradiation at 0.5 and 1mW/cm2 power densities, a rapid distribution of pyroantimonate precipitable calcium content was observed. The pyroantimonate deposits were located on the cytoplasmic side of lateral membrane, in the area of junctional complex, including tight junction, and in other parts of lateral plasma membrane. These changes were reversible and 24 hours after the irradiation the distribution of pyroantimonate deposits was similar to the control. Continuous waves with same energy not altered the distribution of precipitable calcium. We conclude the low frequency modulated microwave irradiation can modify the calcium distribution without heat effects

Polarized Membrane Domains of Fibroblasts

Data on the heterogeneous distribution of various membrane domains on the surface of fibroblasts are reviewed. Polarized localization of negative charges is demonstrated and new results on the development and maintenance of polarity in primary human fibroblasts are presented. Cell membrane heterogeneity in fibroblasts and in other cells is compared. Our results indicate that the regional localization of membrane domains of fibroblasts, and their dependence on cell movement and cell contacts is in several aspects similar to that described for epithelial cells

The Effects of Low Doses of Ionizing Radiation Upon the Micromorphology and Functional State of Cell Surface

The cellular membrane as one of the targets of ionizing radiation might play an important role in the development and modification of radiation-induced alterations after low doses. The present paper reviews the micromorphological and functional changes of plasma membranes of irradiated blood and cultured cells with special emphasis on the surface conditions: lectin binding, negative surface charges. The review is completed by our own studies on distribution of positive surface charges and the bindings of two lectins, the Concanavalin A and the wheat germ agglutinin. It was found that the decrease of negative surface charges is unconcomitant with appearance of domains exposing positive ones, particularly on the surfaces of rufflings. The distribution of Concanavalin A binding sites turned from a uniform distribution to a polarized one, especially on apical regions where it appeared in large aggregates. The polarity in localization of wheat germ agglutinin on untreated fibroblasts observed in our experiments ceased shortly after irradiation

Morphological and Histochemical Changes in Intercellular Junctional Complexes in Epithelial Cells of Mouse Small Intestine Upon X-Irradiation: Changes of Ruthenium Red Permeability and Calcium Content

Changes of calcium-content and permeability of tight junction following X-irradiation were investigated in mouse intestinal epithelial cells by electron microscopy. In the control animals the lower parts of tight junctional area as well as the other junctional elements and the intercellular space are labeled by pyroantimonate precipitates, which contain calcium as revealed by electron spectroscopy and electron energy loss spectrometry. X-irradiation, parallel with morphological changes, lead to rapid decrease of pyroantimonate precipitable calcium content and increase of the permeability of tight junctions indicated by the penetration of ruthenium red into the intercellular space. These changes were readily reversible following 0,5 Gy doses of irradiation however, they persisted up to 24 hours following 5 Gy irradiation. We conclude that irradiation at the applied doses can transiently destabilize the tight junctions in the epithelial layer of the small intestine, presumably through a calcium dependent mechanism

Effects of Low Energy Beta-Irradiation from Tritiated Water on the Morphology of 3T3 Fibroblasts

Cellular alterations of cultured 3T3 cells irradiated with beta-rays from tritiated water were studied by scanning and transmission electron microscopy. We observed decreased negative surface charges, vacuolization of rough endoplasmic reticulum and Golgi-complex, degeneration of mitochondria, increase of lysosomal activity and changes in distribution and amount of microfilaments in the irradiated cells, that parallelled changes in cell shape

Effects of Modulated Microwave and X-Ray Irradiation on the Activity and Distribution of Ca2+-ATPase in Small Intestine Epithelial Cells

The distribution and activity of Ca2+-ATPase were investigated by histochemical methods in small intestine epithelial cells of mice following total body 2450 MHz low frequency (16 Hz) microwave and X-ray irradiation. In the control animals, enzyme activities were found in the brush border and on lateral membranes, including junctional areas of the cells. The enzyme activity of lateral membranes was inhibited by quercetin, a specific inhibitor of Ca2+-ATPase. Immediately after square modulated (16 Hz) 2450 MHz microwave irradiation at 1 mW/cm2 power densities, we observed a decreased activity of Ca2+-ATPase on the lateral membrane regions. The X-ray irradiation (1 Gy) induced a similar decrease of Ca2+-ATPase activity which was reversible within 24 hours. 5 Gy doses resulted in a decrease of enzyme activities on both apical and lateral membrane areas persisting up to 24 hours following irradiation

Effects of Modulated and Continuous Microwave Irradiation on the Morphology and Cell Surface Negative Charge of 3T3 Fibroblasts

Mouse embryo 3T3 cells were irradiated with 2450 MHz continuous and low frequency (16 Hz) square modulated waves of absorbed energy ranging from 0.0024 to 2.4 mW/g. The low frequency modulated microwave irradiation yielded more morphological cell changes than did the continuous microwave fields of the same intensity. The amount of free negative charges (cationized ferritin binding) on cell surfaces decreased following irradiation by modulated waves but remained unchanged under the effect of a continuous field of the same dose. Modulated waves of 0.024 mW/g dose increased the ruffling activity of the cells, and caused ultrastructural alteration in the cytoplasm. Similar effects were experienced by continuous waves at higher (0.24 and 2.4 mW/g) doses

X-Irradiation-Induced Disorganization of Cytoskeletal Filaments and Cell Contacts in HT29 Cells

Organization of cytoskeleton and cell contacts were studied by immunochemistry and electron microscopy in confluent HT29 cultured cells following exposure to 0.5 and 1.0 Gy doses of X-ray. Microtubules were resistant to irradiation, whereas, the actin and intermediate filaments disrupted rapidly following the treatment and their components appeared as clumps of actin and cytokeratin aggregates in the cytoplasm as demonstrated by immunochemistry. Loss of cell contacts and decrease in the number of desmosomes was also characteristic of irradiated cells. Electron microscopy revealed intact desmosomes in control cells and abnormal desmosomes in the irradiated samples characterized by the absence of tonofilaments. The perinuclear filament network and cortical filaments were well detectable by electron microscopy. Under the effect of irradiation, the perinuclear filaments almost disappeared and, at the same time, small bundles of filaments were formed irregularly in the cytoplasm associated with amorphous material

Surface Heterogeneity of Tumor Cells and Changes Upon Ionizing Radiation

Heterogeneous distribution of surface domains is a characteristic feature of the tumor cell surface and the distribution differs from that of normal cells. During the malignant transformation the heterogeneity may change or disappear. Cell lines with various metastasizing capacities show different distributions of membrane domains or other differences in membrane or surface organization. We have demonstrated that the amount and distribution of negatively charged sites of B 16 melanoma membranes changed upon ionizing radiation (X-ray, 60Co-gamma). In the case of the P 388 lymphoma, however, only the amount of negatively charged sites change after irradiation, the distribution remains unaltered. Both features proved to be radioresistant in human lymphoid leukemic cells

Effect of X-Irradiation on Adenylate Cyclase Activity and Cyclic AMP Content of Primary Human Fibroblasts

Ionizing radiation provokes an increase of the cAMP level in several organs and body fluids. After reviewing the relevant literature we present the results of our own experiments on primary human fibroblasts. X-irradiation at doses of 0.5 and 2.5 Gy in vitro evoked a rapid and reversible increase of adenylate cyclase enzyme activity. A significant increase in cAMP level of these cells was also observed. Adenylate cyclase was usually localized basolaterally on the surface of unirradiated cells, while irradiation resulted in a modification of distribution, i.e., the enzyme activity also appeared in apical localization