Variance analysis of gamma-aminobutyric acid (GABA)-ergic inhibitory postsynaptic currents from melanotropes of Xenopus laevis.
AUTOR(ES)
Borst, J G
RESUMO
We have studied the variance in the decay of large spontaneous gamma-aminobutyric acid (GABA)-ergic inhibitory postsynaptic currents (IPSCs) in melanotropes of Xenopus laevis to obtain information about the number of GABAA receptor channels that bind GABA during the IPSCs. The average decay of the IPSCs is well described by the sum of two exponential functions. This suggests that a three-state Markov model is sufficient to describe the decay phase, with one of the three states being an absorbing state, entered when GABA dissociates from the GABAA receptor. We have compared the variance in the decay of large spontaneous IPSCs with the variance calculated for two different three-state models: a model with one open state, one closed state, and one absorbing state (I), and a model with two open states and one absorbing state (II). The data were better described by the more efficient model II. This suggests that the efficacy of GABA at synaptic GABAA receptor channels is high and that only a small number of channels are involved in generating the GABA-ergic IPSCs.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1225348Documentos Relacionados
- Relationship between presynaptic calcium transients and postsynaptic currents at single γ-aminobutyric acid (GABA)ergic boutons
- Release of gamma-aminobutyric acid from inhibitory nerves of lobster.
- Modulation of gamma-aminobutyric acid-mediated inhibitory synaptic currents in dissociated cortical cell cultures.
- Lasting potentiation of inhibition is associated with an increased number of gamma-aminobutyric acid type A receptors activated during miniature inhibitory postsynaptic currents.
- Autoradiographic localization of gamma-aminobutyric acid (GABA) receptors in the rat cerebellum.
