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Inhibition of sodium currents in acutely isolated hippocampal CA_(1) neurons of rats by magnesium sulfate

Sang Nan, Meng Ziqiang

Institute of Environmental Medicine and Toxicology,Shanxi University.Taiyuan 030006,Shanxi

Abstract

The effects of magnesium sulfate (MgSO_(4)) 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 MgSO_(4) 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 result also showed that 4 mmol/L MgSO_(4) shifted the steady state activation curve of Na~(+) currents towards positive potential (control V_(h)=-55.8+-6.8 mV, MgSO_(4) 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 MgSO_(4) might be an interpretation for its neuroprotection against damages induced by ischemia and oxygen deprivation.

Key words: Hippocampus;CA_(1) neuron;Patch-clamp technique;Magnesium sulfate[MgS0_(4)]

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Citing This Article：

Sang Nan, Meng Ziqiang. Inhibition of sodium currents in acutely isolated hippocampal CA_(1) neurons of rats by magnesium sulfate. Acta Physiol Sin 2002; 54 (6): (in Chinese with English abstract).