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ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCTED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS
Citation:
Blackman, C F., J. Page, S G. Benane, AND S. Machlup. ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCTED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS. Presented at Bioelectromagnetics Society Annual Meeting, Maui, Hawaii, June 21-26, 2003.
Description:
ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS.
OBJECTIVE: We have shown that functional gap junction communication as measured by Lucifer yellow dye transfer (DT) in Clone-9 rat liver epithelial cells, could be inhibited by vertical, parallel AC and DC magnetic fields. Recently, Stefan Machlup developed a model of our exposure conditions using a spherical cell. His calculations predicted that only specific areas on the surface of the cell would be at the correct angle to the parallel fields to exhibit biological changes. To evaluate the possibility raised by Machlup, we tested DT in Clone-9 cells, which grow in a flattened monolayer on culture dish surfaces. We compared DT results following exposure to parallel AC magnetic fields (Bac) and DC magnetic fields (Bdc) oriented vertically, with the same fields oriented horizontally.
METHODS: An epithelial rat liver cell line from the American Type Culture Collection, designated Clone 9, demonstrates substantial functional intercellular communication when assayed by the Scrape/Load Dye Transfer (DT) assay developed by El-Fouley et al. (1987). Chloral hydrate is used to partially inhibit DT as the cells are exposed to 25Hz sinusoidal Bac at a flux density of 215 mGrms (21.5 uTrms) with a corresponding Bdc of 328 mG (32.8 uTrm) parallel, and < 2 mG (0.2 uT) perpendicular to Bac. The samples and the coils were enclosed in a magnetically shielded box (co-netic metal) housed in a 5% C02 incubator maintained at 37 degrees C. Following a 30-minute exposure, the dishes are examined for the transfer of the fluorescent dye, Lucifer Yellow. The exposure conditions were selected from predictions of the IPR model to be resonant for calcium ions. Two sample exposures were conducted: in one, the 25-Hz Bac and the Bdc were vertical, impinging on the broad flat surface to the cells, and in the other, the fields were horizontal, impinging edge-on to the monolayer.
RESULTS: The amount of DT was reduced in the cells exposed to vertical oriented fields compared to cells exposed to horizontally oriented fields. The DT in the horizontally exposed cells was identical to that in unexposed cells.
DISCUSSION: These experimental results are also consistent with the theoretical predictions of the spherical cell model of Machlup. This is an intriguing finding that merits further investigation. Previously, we demonstrated that vertical, parallel AC and DC magnetic fields could alter the neurite outgrowth in PC-12 cells (Blackman et al., 1994) and that changes in the angle of the DC component away from vertical AC component could alter this response (Blackman et al., 1996). The results in these studies identified critical parameters that can control the biological responses to magnetic fields: AC flux density and frequency, and DC flux density and angle with respect to the AC magnetic field. The results reported here identify an additional exposure parameter that must be considered when cell cultures, and perhaps cellular/tissue complexes, are exposed to magnetic fields, namely, the relative angle of the exposure to fixed cellular components.
Authors supported by USEPA (CFB, SGB) and by DOE (CFB), IAG# DE-A10194CE34007. This abstract does not reflect EPA policy.