[Inhibition of sodium currents in acutely isolated hippocampal CA1 neurons of rats by magnesium sulfate].
The effects of magnesium sulfate (MgSO4) on sodium currents (Na(+) currents) were studied in freshly dissociated hippocampal CA(1) neurons of rat using the whole-cell patch-clamp technique. The results indicated that MgSO4 caused a concentration-dependent and voltage-dependent decrease in Na(+) currents. The half-inhibitory concentration (IC(50)) was 4.05 mmol/L. This action was frequency-independent. The results also showed that 4 mmol/L MgSO4 shifted the steady state activation curve of Na(+) currents towards positive potential (control V(h)=-55.8+/-6.8 mV, MgSO4 V(h)=-34.2+/-6.2 mV, n=8, P<0.01) without changing the slope factor. However, the steady state inactivation curve was not affected. These results suggest that blockade of Na(+) currents by MgSO4 might be an interpretation for its neuroprotection against damages induced by ischemia and oxygen deprivation.
Sang
Nan
N
Institute of Environmental Medicine and Toxicology, Shanxi University, Taiyuan 030006.
Meng
Zi-Qiang
ZQ
D000818:Animals; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008278:Magnesium Sulfate / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D015222:Sodium Channels / Q000502:physiology
D026941:Sodium Channel Blockers; D015222:Sodium Channels; D008278:Magnesium Sulfate