Intracellular chloride and calcium transients evoked by ?-aminobutyric acid and glycine in neurons of the rat inferior colliculus
✍ Scribed by Frech, Moritz J. ;Deitmer, Joachim W. ;Backus, Kurt H.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 123 KB
- Volume
- 40
- Category
- Article
- ISSN
- 0022-3034
No coin nor oath required. For personal study only.
✦ Synopsis
Microfluorometric recordings showed
that the inhibitory neurotransmitters ␥-aminobutyric acid (GABA) and glycine activated transient increases in the intracellular Cl ؊ concentration in neurons of the inferior colliculus (IC) from acutely isolated slices of the rat auditory midbrain. Current recordings in gramicidin-perforated patch mode disclosed that GABA and glycine mainly evoked inward or biphasic currents. These currents were dependent on HCO 3
؊ and characterized by a continuous shift of their reversal potential (E GABA/gly ) in the positive direction. In HCO 3 ؊ -buffered saline, GABA and glycine could also evoke an increase in the intracellular Ca 2؉ concentration. Ca 2؉ transients occurred only with large depolarizations and were blocked by Cd 2؉ , suggesting an activation of voltage-gated Ca 2؉ channels. However, in the absence of HCO 3 ؊ , only a small rise, if any, in the intracellular Ca 2؉ concentration could be evoked by GABA or glycine. We suggest that the activation of GABA A or glycine receptors results in an acute accumulation of Cl ؊ that is enhanced by the depolarization owing to HCO 3 ؊ efflux, thus shifting E GABA/gly to more positive values. A subsequent activation of these receptors would result in a strenghtened depolarization and an enlarged Ca 2؉ influx that might play a role in the stabilization of inhibitory synapses in the auditory pathway.