Characteristics of GABA-activated chloride channels in mammalian dorsal root ganglion neurones.

摘要: 1. The properties of gamma-aminobutyric acid (GABA)-activated chloride channels in dorsal root ganglion (DRG) neurones obtained from rats and cats were examined using the single-electrode voltage clamp conjunction with suction-electrode techniques. 2. GABA-evoked currents showed voltage-sensitive kinetics. Time constants (tau D) measured voltage-jump relaxations tau D became briefer membrane hyperpolarization. was 33 ms at -120 mV 60 microM-GABA changed e-fold for 188 mV. decreased as GABA concentration increased - extrapolated 'zero' approximately equal to 50 3. steady-state current curvilinear, rectifying negative potentials. instantaneous linear symmetrical concentrations (140 mM) on both sides cell membrane. 4. Muscimol a more effective agonist than GABA, while piperidine-4-sulphonic ethylenediamine monocarbamate only weakly agonists. Taurine glycine had no detectable activity. 5. Ion substitution experiments revealed permeability sequence I- greater Br- Cl- F- propionate (1.88 1.21 1.0 0.1 0.1). 6. presence iodide bromide ions externally caused an increase efflux potentials -40 mV, prolongation relaxations. Relaxations fluoride solutions faster those seen chloride.