Effects of a time varying strong magnetic field on release of cytosolic free Ca²⁺ from intracellular stores in cultured bovine adrenal chromaffin cells

Abstract

Abstract This study was made to explain the mechanisms for the effects of exposure to a time varying 1.51 T magnetic field on the intracellular Ca 2+ signaling pathway. The exposure inhibited an increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) in bovine chromaffin cells induced by addition of bradykinin (BK) to a Ca 2+ free medium. The exposure did not change BK induced production of inositol 1,4,5‐trisphosphate (IP 3 ). [Ca 2+ ] i was markedly increased in IP 3 loaded cells, and this increase was inhibited by the magnetic field exposure. A similar increase in [Ca 2+ ] i by other drugs, which stimulated Ca 2+ release from intracellular Ca 2+ stores, was again inhibited by the same exposure. However, transmembrane Ca 2+ fluxes caused in the presence of thapsigargin were not inhibited by the magnetic field exposure in a Ca 2+ containing medium. Inhibition of the BK induced increase in [Ca 2+ ] i by the exposure for 30 min was mostly recovered 1 h after exposure ended. Our results reveal that the magnetic field exposure inhibits Ca 2+ release from intracellular Ca 2+ stores, but that BK bindings to BK receptors of the cell membrane and intracellular inositol IP 3 production are not influenced. Bioelectromagnetics 23:505–515, 2002. © 2002 Wiley‐Liss, Inc.