| 12505654 |
Yu K, Ge SY, Ruan DY: Fe2+ decreases the taurine-induced Cl- current in acutely dissociated rat hippocampal neurons. Brain Res. 2003 Jan 17;960(1-2):25-35.
The effects of ferrous ions (Fe (2+)) on taurine-induced Cl (-) current (I (tau)) recorded from single neurons, which was freshly isolated from the rat hippocampal CA1 area, were studied with conventional whole-cell recording under voltage-clamp conditions. Using standard pharmacological approaches, we found that the currents gated by concentrations of taurine (neurons tested, were predominantly mediated by strychnine-sensitive glycine receptors. When co-applied with taurine, Fe (2+) effectively depressed I (tau) in a concentration-dependent manner, with an IC (50) of 3.76 mM and Hill coefficient of 1.01, while preincubation with 1 mM Fe (2+) alone did not affect the following membrane currents elicited by taurine. The result suggests that resting taurine-gated channels are insensitive to Fe (2+). Since internal cell dialysis with 3 mM Fe (2+) failed to modify I (tau), it was deduced that the site of action of Fe (2+) is extracellular. Furthermore, the Lineweaver-Burke double reciprocal plot of normalized response to taurine against the concentration of taurine illustrated that the depression of I (tau) was noncompetitive, therefore Fe (2+) may act on the glycine receptor-chloride ionophore complex at a site distinct from where taurine binds. Various concentrations of Fe (2+) ranging from 0.1 to 20 mM depressed I (tau) and this extracellular depression was independent of membrane voltage. These results indicate that Fe (2+) decreases I (tau) in acutely dissociated rat hippocampal neurons and the inhibition of glycine receptors by Fe (2+) might be one possible approach through which Fe (2+) induces seizures. |
1(0,0,0,1) |