Electromagnetic fields from a high-field nuclear magnetic resonance (NMR) imaging instrument (Static: 2.3T; RF: 100 MHz; Gradient Field: 1.0 T/s at 1 mT; 60 min exposure at 37 degree C) are shown to enhance calcium transport in vitro in rat thymocytes and in human peripheral blood lymphocytes. Additional studies indicate that thymocytes from mature compared to juvenile rats respond more vigorously. Spectral analysis of the nuclear magnetic resonance (NMR) gradient field indicates that extremely low frequency (ELF) components at 20, 40 and 60 Hz are prominent in the NMR imaging exposure. Independently, the applicants have shown that a 60 Hz sinusoidal magnetic field can stimulate calcium transport in the rat thymocyte. These findings demonstrate for the first time that (1) high-field NMR signals can stimulate net calcium transport in the lymphocyte, particularly in the mature lymphocyte, and (2) that nonthermal ELF components in the NMR gradient field may play a role in this response. The applicants propose studies using rodent and human lymphocytes that will: (1) determine whether the static, gradient, and/or RF field(s) contribute to this calcium response, and then establish a threshold value; (2) characterize the age-dependence for rodent and human lymphocyte responses; and (3) since calcium is an important second messenger, characterize the alteration of the following membrane signal transduction events: [Ca2+]i, inositol 1,4,5-triphosphate turnover, protein kinase C activation and, importantly, whether subsequent DNA and protein synthesis is altered. This research will carefully define lymphocyte responses to electromagnetic fields associated with high-field NMR. It should assist future design efforts for emerging high-field NMR systems.
| Liburdy, R P; Callahan, D E; Harland, J et al. (1993) Experimental evidence for 60 Hz magnetic fields operating through the signal transduction cascade. Effects on calcium influx and c-MYC mRNA induction. FEBS Lett 334:301-8 |
| Liburdy, R P (1992) Calcium signaling in lymphocytes and ELF fields. Evidence for an electric field metric and a site of interaction involving the calcium ion channel. FEBS Lett 301:53-9 |
| Liburdy, R P (1992) Biological interactions of cellular systems with time-varying magnetic fields. Ann N Y Acad Sci 649:74-95 |
