| 초록 |
Substantia nigra is known to highly express glibenclamide binding site, a protein associated to ATP-sensitive $K^{+}$ ( $K_{ATP}$ ) channel in the brain. However, the functional expression of $K_{ATP}$ channels in the area is not yet known. In this work, we attempted to estimate the functional expression of $K_{ATP}$ channels in neurons of the substantia nigra pars compacta (SNC) in young rats using slice patch clamp technique. Membrane properties and whole cell currents attributable to $K_{ATP}$ channel were examined by the current and voltage clamp method, respectively. In SNC, two sub-populations of neurons were identified. Type I (rhythmic) neurons had low frequency rebound action potentials ( $4.5{ pm}0.25Hz$ , n=75) with rhythmic pattern. Type II (phasic) neurons were characterized by faster firing ( $22.7{ pm}3.16Hz$ , n=12). Both time constants and membrane capacitance in rhythmic neurons ( $34.0{ pm}1.27$ ms, $270.0{ pm}11.83$ pF) and phasic neurons ( $23.7{ pm}4.16$ ms, $184{ pm}35.2$ pF) were also significantly different. The current density of $K_{ATP}$ channels was $6.1{ pm}1.47$ pA/pF (2.44~15.43 pA/pF, n=8) at rhythmic neurons of young rats. Our data show that in SNC there are two types of neurons with different electrical properties and the density of $K_{ATP}$ , channel of rhythmic neuron is about 600 channels per neuron. |
