Effects of moderate static magnetic fields on the voltage-gated sodium and calcium channel currents in trigeminal ganglion neurons.
OBJECTIVE
To study the effects of static magnetic fields (SMF) on the electrophysiological properties of voltage-gated sodium and calcium channels on trigeminal ganglion (TRG) neurons.


METHODS
Acutely dissociated TRG neurons of neonatal SD rats were exposed to 125-mT and 12.5-mT SMF in exposure devices and whole-cell patch-clamp recordings were carried out to observe the changes of voltage-gated sodium channels (VGSC) and calcium channels (VGCC) currents, while laser scanning confocal microscopy was used to detect intracellular free Ca(2+) concentration in TRG neurons, respectively.


RESULTS
(1) No obvious change of current-voltage (I-V) relationship and the peak current densities of VGSC and VGCC currents were found when TRG neurons were exposed to 125-mT and 12.5-mT SMF. However, the activation threshold, inactivation threshold and velocity of the channel currents above were significantly altered by 125-mT and 12.5-mT SMF. (2) The fluctuation of intracellular free Ca(2+) concentration within TRG neurons were slowed by 125-mT and 12.5-mT SMF. When SMF was removed, the Ca(2+) concentration level showed partial recovery in the TRG neurons previously exposed by 125-mT SMF, while there was a full recovery found in 12.5-mT-SMF-exposed neurons.


CONCLUSIONS
Moderate-intensity SMF could affect the electrophysiological characteristics of VGCS and VGCC by altering their activation and inactivation threshold and velocity. The fluctuations of intracellular free Ca(2+) caused by SMF exposure were not permanent in TRG neurons.
a State Key Laboratory of Oral Diseases and.|b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Xiao-Wen
XW
Lu
b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Li
L
Du
a State Key Laboratory of Oral Diseases and.|b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Liang
L
Kou
a State Key Laboratory of Oral Diseases and.|b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Ning
N
Song
a State Key Laboratory of Oral Diseases and.|b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Yu-Jiao
YJ
Zhang
a State Key Laboratory of Oral Diseases and.|b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Min-Ke
MK
Wu
a State Key Laboratory of Oral Diseases and.|b Department of Prosthodontics , West China Hospital of Stomatology, Sichuan University , Chengdu , China.
Jie-Fei
JF
Shen
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000737:chemistry; D015220:Calcium Channels / Q000378:metabolism*; D060526:Magnetic Fields; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012668:Trigeminal Ganglion / Q000378:metabolism*; D061566:Voltage-Gated Sodium Channels / Q000378:metabolism*
D015220:Calcium Channels; D061566:Voltage-Gated Sodium Channels; D002118:Calcium
12.5-mT; 125-mT; calcium channel; sodium channel; static magnetic fields; trigeminal ganglion neuron; whole-cell patch-clamp