Electrical properties and ATP-sensitive K+ channel density of the rat substantia nigra pars compacta neurons

랫드 흑질 신경세포의 전기적 특성과 ATP-sensitive K+채널의 전류밀도

  • Han, Seong-kyu (Department of Pharmacology, College of Veterinary Medicine, Seoul National University) ;
  • Park, Jin-bong (Department of Physiology, College of Medicine, Chungnam National University) ;
  • Ryu, Pan-dong (Department of Pharmacology, College of Veterinary Medicine, Seoul National University)
  • 한성규 (서울대학교 수의과대학 약리학교실) ;
  • 박진봉 (충남대학교 의과대학 생리학교실) ;
  • 류판동 (서울대학교 수의과대학 약리학교실)
  • Accepted : 2000.04.21
  • Published : 2000.06.25

Abstract

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.