A quantitative study of the γ-aminobutyric acid (GABA) dose/conductance relationship at the lobster inhibitory neuromuscular junction
1977; Elsevier BV; Volume: 16; Issue: 5 Linguagem: Inglês
10.1016/0028-3908(77)90073-9
ISSN1873-7064
Autores Tópico(s)Neuroscience and Neural Engineering
ResumoGABA-evoked changes in membrane conductance of lobster muscle fibres were measured using the ‘short’ cable equations. In 79 fibres, the mean resting conductance (ℷmL) was 12.9μmho (S.D. ± 5.6 μmho). In the presence of GABA (5 μM to 640 μM) the membrane conductance increased with little change in resting potential and with no visible decline in response during exposure. In contrast with the non-cumulative GABA dose/conductance curves, cumulatively established curves attained an apparent maximum at GABA concentrations exceeding 80 μM. The non-cumulative dose/conductance curve was better fitted by a two independent binding-site receptor model than by a two-site high facilitation model or a single-site model. Values for the apparent GABA/receptor dissociation constant estimated by ‘least squares’ analysis (on the basis of the independent model) were similar to those estimated by double reciprocal plot (ca. 30 μM).
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