RESUMO
<p><b>AIM</b>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.</p><p><b>METHODS</b>The whole-cell patch clamp techniques were used.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSION</b>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.</p>
Assuntos
Animais , Feminino , Masculino , Ratos , Separação Celular , Canais de Potássio de Retificação Tardia , Hipocampo , Biologia Celular , Sulfato de Magnésio , Farmacologia , Neurônios , Fisiologia , Fármacos Neuroprotetores , Farmacologia , Técnicas de Patch-Clamp , Canais de Potássio , Metabolismo , Canais de Potássio de Abertura Dependente da Tensão da Membrana , Ratos WistarRESUMO
The effect of SO2 derivatives on Na(+) currents was studied in freshly dissociated hippocampal CA1 neurons of rat using the whole-cell patch-clamp technique. The results indicated that SO2 derivatives caused a dose-dependent and voltage-dependent increase in the voltage-activated Na+ currents. The amplitudes of Na(+) currents were increased by 50.59 19.08% and 82.06 18.51% (n=15)by SO2 derivatives at 10 and 100 micromol/L, respectively. The action was frequency-independent. The results also showed that SO2 derivatives did not affect the activation process, but changed the inactivation process significantly. Before and after application of 10 micromol/L SO2 derivatives, the half-inactivation voltage was -69.71+/-4.67 and -53.27+/-4.95 mV (n=10, P<0.01), respectively, but the slope factor was not changed. These results imply that SO2 derivatives have neurotoxic effects and that SO2 pollution is probably related to some diseases of central neuronal system.
Assuntos
Animais , Feminino , Masculino , Ratos , Relação Dose-Resposta a Droga , Hipocampo , Biologia Celular , Potenciais da Membrana , Neurônios , Fisiologia , Técnicas de Patch-Clamp , Ratos Wistar , Canais de Sódio , Fisiologia , Sulfitos , ToxicidadeRESUMO
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.
Assuntos
Animais , Ratos , Hipocampo , Biologia Celular , Fisiologia , Sulfato de Magnésio , Farmacologia , Neurônios , Fisiologia , Técnicas de Patch-Clamp , Ratos Wistar , Bloqueadores dos Canais de Sódio , Farmacologia , Canais de Sódio , FisiologiaRESUMO
The developments of domestic and foreign researches on mutagenesis of sulfur dioxide were briefly reviewed in this paper from different aspects: microbiological experiments, the experiments of cultured mammalian cells in vitro,experiments on mammal and population in vivo.
RESUMO
Objective To study the genetic effects of lead on root tip cell of Vicia faba. Methods Micronucleus tests were conducted on root tip cell of Vicia faba treated with Pb2+ of concentrations of 0.1, 1.0, 5.0, 25.0, 50.0 mg/L for 12-36 h. Results The results indicated that the rates of micronucleus of lead-treated tip cell were significantly higher than that of the control (P