60 Hz electric field upregulates cytosolic Ca2+ level in mouse splenocytes stimulated by lectin.
The effect of a 60 Hz electric field (EF) on alteration of cytosolic free Ca2+ level ([Ca2+]c) was examined in mouse splenocytes stimulated by lectins, namely concanavalin A (ConA) or phytohemagglutinin. In order to understand the role of EF on alterations in [Ca2+]c and to determine whether EF exposure increased cell mortality the splenocytes were cultured under the 60 Hz EFs producing current densities of 6 or 60 microA/cm2 for 30 min or 24 h. Cell mortality was less than 2% in experimental all conditions. [Ca2+]c in the splenocyte was not changed by the 6 microA/cm2 exposure alone, while a lectin-induced [Ca2+]c elevation in the EF exposed cells was significantly higher than that of the sham exposed cells (P <.05: ANOVA, P <.05: paired t-test). Moreover, the enhanced increase of [Ca2+]c in the EF exposed, lectin stimulated cells was only observed in the presence of extracellular Ca2+. The EF dependent upregulation of [Ca2+]c persisted after EF exposure (P <.05: paired t-test). The results clearly indicate that Ca2+ influx across the plasma membrane is responsible for the enhanced increase of [Ca2+]c in the EF exposed, lectin stimulated cells and that EF has persistent effect on the cells. Although the precise mechanisms of the EF dependent upregulation of [Ca2+]c is not fully elucidated, the present results demonstrate that the 60 Hz EF (6 microA/cm2) affects [Ca2+]c during cell activation via a Ca2+ influx pathway induced by lectin stimulation.
Harakawa
Shinji
S
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan. harakawa@bd5.so-net.ne.jp
Inoue
Noboru
N
Saito
Atsushi
A
Doge
Fuyuki
F
Nagasawa
Hideyuki
H
Suzuki
Naoyoshi
N
Martin
David E
DE
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism; D004560:Electricity; D005260:Female; D005434:Flow Cytometry; D051379:Mice; D008807:Mice, Inbred BALB C; D010835:Phytohemagglutinins / Q000494:pharmacology*; D013154:Spleen / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D010835:Phytohemagglutinins; D003208:Concanavalin A