Blockade by magnesium of sodium currents in acutely isolated hippocampal CA1 neurons of rat.
The effects of magnesium (MgSO(4)) on sodium currents (Na(+) currents) in freshly dissociated rat hippocampal neurons were studied using the whole-cell patch clamp techniques. MgSO(4) caused a concentration-dependent and voltage-dependent reversible decrease of Na(+) currents. The half-blocking concentration (IC(50)) of MgSO(4) on Na(+) currents was 4.05 mM. But the action was frequency-independent. In addition, 4 mM MgSO(4) shifted the steady state activation curve of Na(+) currents toward positive potential (control V(h)=-55.83+/-6.79 mV, MgSO(4)V(h)=-34.15+/-6.18 mV, n=8, P</=0.01 without changing the slope factor). However, the steady state inactivation curve was not affected. These results suggested that blockade of MgSO(4) on Na(+) currents 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, PR China.
Meng
Ziqiang
Z
D000818:Animals; D000831:Animals, Newborn; D002469:Cell Separation; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D015640:Ion Channel Gating / Q000187:drug effects*; D008278:Magnesium Sulfate / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; 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