[Blockade of magnesium sulfate on transient outward K+ current and delayed rectifier K+ current in acutely isolated rat hippocampal neurons].
OBJECTIVE
To study the effect of magnesium sulfate on transient outward K+ current (IA) and delayed rectifier K+ current (IK) in freshly dissociated hippocampal neurons of rats.


METHODS
The whole-cell patch clamp techniques were used.


RESULTS
Magnesium sulfate reversibly reduced the amplitudes of IA and IK in a concentration-dependent and voltage-dependent, but not frequency-dependent manner. Half-blocking concentration (IC50) on IA and IK were 6.30 mmol.L-1 and 7.60 mmol.L-1, respectively. Magnesium sulfate (6 mmol.L-1) affected the activation process of IA and IK. Before and after application of the drug, the half-activation voltages of IA were (7 +/- 6) mV and (-7 +/- 11) mV (n = 10, P < 0.01), and the half-activation voltages of IK were (20 +/- 6) mV and (28 +/- 4) mV (n = 10, P < 0.01), but the slope factors were not changed. In addition, magnesium sulfate (6 mmol.L-1) also affected the inactivation process of IA. Before and after application of the drug, the half-inactivation voltages of IA were (-65 +/- 5) mV and (-89 +/- 6) mV (n = 10, P < 0.01).


CONCLUSIONS
Magnesium sulfate inhibited IA and IK in freshly dissociated hippocampal neurons of rats, which might contribute to protect the central neuronal system (CNS) against damages induced by ischemia and oxygen deprivation.
Sang
Nan
N
Institute of Environmental Medicine and Toxicology, Shanxi University, Taiyuan 030006, China.
Meng
Zi-qiang
ZQ
D000818:Animals; D002469:Cell Separation; D051668:Delayed Rectifier Potassium Channels; D005260:Female; D006624:Hippocampus / Q000166:cytology*; D008278:Magnesium Sulfate / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D017208:Rats, Wistar
D051668:Delayed Rectifier Potassium Channels; D018696:Neuroprotective Agents; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D008278:Magnesium Sulfate