In the past ten years, the physiological functions of Nitric Oxide in the central nervous system have been studied by more and more research groups in the world. In this study, we directly examined the effect of Nitric Oxide on the voltage-dependent medium-conductance potassium channel that is located on the cell bodies of Tat: Icr: Ha (ICR) fBR mice cortical neurons employing patch clamp techniques. Patch clamp technique is an extremely powerful and versatile method for studying the electrophysiologal properties of ion-channels in biological membranes....[ Read more ]

In the past ten years, the physiological functions of Nitric Oxide in the central nervous system have been studied by more and more research groups in the world. In this study, we directly examined the effect of Nitric Oxide on the voltage-dependent medium-conductance potassium channel that is located on the cell bodies of Tat: Icr: Ha (ICR) fBR mice cortical neurons employing patch clamp techniques. Patch clamp technique is an extremely powerful and versatile method for studying the electrophysiologal properties of ion-channels in biological membranes.

With the data obtained from cell-attached and inside-out recordings, we found that: (1) nitric oxide has dual effect on the intermedium conductance potassium channel. At low concentration (0.3 μM), it can activate the channel activity, while at high concentration (1.0 μM), it can inhibit the channel activity; and (2) the activation effect of low concentration nitric oxide is via a cGMP-dependent pathway while the inhibition effect of high concentration nitric oxide is via a cGMP-independent pathway, which is further proven to be oxidation mechanism.

Superoxide is also a free radical with oxidant effect just like NO, it can react with NO to form ONOO^-. From our study, we found that superoxide can inhibit the intermedium conductance potassium channel's activity by oxidizing the channel protein.