Effects of weak environmental magnetic fields on the spontaneous bioelectrical activity of snail neurons.
We examined the effects of 50-Hz magnetic fields in the range of flux densities relevant to our current environmental exposures on action potential (AP), after-hyperpolarization potential (AHP) and neuronal excitability in neurons of land snails, Helix aspersa. It was shown that when the neurons were exposed to magnetic field at the various flux densities, marked changes in neuronal excitability, AP firing frequency and AHP amplitude were seen. These effects seemed to be related to the intensity, type (single and continuous or repeated and cumulative) and length of exposure (18 or 20 min). The extremely low-frequency (ELF) magnetic field exposures affect the excitability of F1 neuronal cells in a nonmonotonic manner, disrupting their normal characteristic and synchronized firing patterns by interfering with the cell membrane electrophysiological properties. Our results could explain one of the mechanisms and sites of action of ELF magnetic fields. A possible explanation of the inhibitory effects of magnetic fields could be a decrease in Ca(2+) influx through inhibition of voltage-gated Ca(2+) channels. The detailed mechanism of effect, however, needs to be further studied under voltage-clamp conditions.
Department of Medical Physics, Medical Faculty, Tarbiat Modares University, Tehran, Iran.
Mehri Kaviani
MK
Moghadam
Mohammad
M
Firoozabadi
Mahyar
M
Janahmadi
D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D015220:Calcium Channels / Q000502:physiology* / Q000528:radiation effects; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004777:Environment; D006372:Helix, Snails / Q000502:physiology* / Q000528:radiation effects; D009474:Neurons / Q000502:physiology* / Q000528:radiation effects; D018408:Patch-Clamp Techniques; D015398:Signal Transduction / Q000528:radiation effects
D015220:Calcium Channels
Bioelectromagnetics. 2001 Feb;22(2):122-8
11180258
J Physiol. 1986 Mar;372:245-59
2425084
J Neurophysiol. 2005 Dec;94(6):3884-92
16093326
Prog Neurobiol. 1994 Dec;44(6):517-601
7701072
Bioelectromagnetics. 1999 Sep;20(6):331-7
10453060
Biofizika. 2009 Nov-Dec;54(6):1120-7
20067194
J Gen Physiol. 1987 Jul;90(1):27-47
2442295
J Neurosci. 2002 Mar 1;22(5):1618-28
11880492
Bioelectromagnetics. 1985;6(4):327-37
3836676
Health Phys. 2009 Sep;97(3):257-8
19667809
J Physiol. 1993 Jun;465:265-87
8229836
Comp Biochem Physiol A Comp Physiol. 1975 Jan 1;50(1A):1-25
234036
Radiat Prot Dosimetry. 2003;106(4):311-6
14690272
Biofizika. 2001 Jan-Feb;46(1):122-5
11236552
Comp Biochem Physiol A Mol Integr Physiol. 2008 Dec;151(4):657-63
18760374
Proc Natl Acad Sci U S A. 1982 Jul;79(13):4180-4
6287472
J Physiol. 1977 Feb;265(2):465-88
850203
Proc Natl Acad Sci U S A. 1976 Jun;73(6):1999-2003
1064869
Bioelectromagnetics. 1985;6(1):1-11
3977964
Brain Res. 2009 Feb 19;1255:57-66
19100724
Gen Pharmacol. 1995 Dec;26(8):1719-26
8745161
Bioelectromagnetics. 1995;16(1):20-32
7748200
Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1999 Sep;124(1):99-107
10579654
J Neurosci. 2005 Nov 2;25(44):10230-8
16267230
Int J Radiat Biol Relat Stud Phys Chem Med. 1987 Nov;52(5):787-93
3500146
J Neurosci. 2000 Nov 15;20(22):8493-503
11069957
Philos Trans R Soc Lond B Biol Sci. 1999 Feb 28;354(1381):347-55
10212483
Bioelectromagnetics. 2003 Sep;24(6):395-402
12929158
J Membr Biol. 2000 Feb 1;173(3):179-85
10667914
Bioelectromagnetics. 1995;16(1):41-7
7748202
Br J Pharmacol. 1986 Jan;87(1):225-32
3006852
Proc Natl Acad Sci U S A. 1978 Dec;75(12):6314-8
282648
Brain Res. 1989 Jun 5;489(1):195-8
2743149
Bioelectromagnetics. 1987;8(2):119-34
3040007