The effects of the voltage-dependent Ca2+inward current (ICa) on γ-aminobutyric acid (GABA)-induced Cl- current (ICl) in isolated sensory neurons were examined at different temperatures and with different concentrations of external Ca2+ using the 'concentration-clamp' technique. The total amount of inhibition of GABA-induced ICl by a preceding ICa increased in a hyperbolic manner with increasing Ca2+ influx. The time course of recovery of the GABA response after inhibition by Ca 2+influx followed a single exponential and was facilitated by warming but slowed dramatically by a slight cooling from 20 to 15 °C in spite of a decrease in Ca2+ influx. It is discussed that the energy-dependent, temperature-sensitive ionic pump and exchange systems at the surface membrane and intracellular organelles regulate the cytoplasmic free Ca2+, thus explaining the quantitative effects of Ca2+ influx and temperature on the inhibition of the GABA-gated Cl- channel.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Clinical Neurology
- Developmental Biology