Adult Rat Hippocampal Ca1 Pyramidal Neurons Outwardly Rectifying Chloride Ion Single-channel Characteristics And Cerebral Ischemia After Channel Activity Persistent Enhancement

An outwardly rectifying chloride channel (ORCC) was characterized in acutely dissociated adult rat hippocampal CA1 pyramidal neurons by using inside-out configuration of patch clamp. These channels were usually active after a delay and depolarizing voltage step. Average single channel conductance was 18.23 ?0.96 pS for membrane potential between -60 and OmV, and 42.26 ?1.2 pS between 0 and +60mV in symmetrical 150 NaCl solution (means ?S.E.M. n = 20). The channel permeability ratio (Pci/Pna) was 12.42. The channel open probability was voltage dependent but insensitive to intracellular Ca2+ concentration. Chloride channel blockers, DIDS, NPPB, SITS, Niflumic acid, and glibenclamide, all showed suppressing effects on the channel activity. Oxidizing reagent DTNB reversibly decreased the channel open probability in a concentration-dependent manner with IC50 of 28.05 ?2.42 umol/L (n = 8). In contrast, reducing reagent DTT had no apparent effect on the channel activity, but could restore the inhibitory effect of DTNB. Another redox couple, GSSG and GSH, exhibited a similar effect as DTNT and DTT. These results provide the first report of an outwardly rectifying chloride channel in hippocampus CA1 pyramidal neurons of adult rat and the channel can be modulated by intracellular redox potential.