| 1. |
- Eghbali, Mansoureh, et al.
(författare)
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Conductance of GABAA channels activated by pentobarbitone in hippocampal neurons from newborn rats.
- 2003
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 552:Pt 1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- Neurons were obtained from the CA1 region of the hippocampus of newborn rats and maintained in culture. Channels were activated by pentobarbitone in cell-attached, inside-out or outside-out patches, normally by applying pentobarbitone in flowing bath solution. Currents were outwardly rectifying and blocked by bicuculline, properties of GABAA channels in these cells. Maximum channel conductance increased as pentobarbitone concentration was increased to 500 microM but conductance then decreased as pentobarbitone concentration was raised further. The best fit of a Hill-type equation to the relationship between maximum channel conductance and pentobarbitone concentration (up to 500 microM) gave an EC50 of 41 microM, a maximum conductance of 36 pS and a Hill coefficient of 1.6. Bicuculline decreased the maximum conductance of the channels activated by pentobarbitone, with an IC50 of 224 microM. Diazepam increased channel conductance, with a maximum effect being obtained with 1 microM diazepam. Diazepam (1 microM) decreased the EC50 of the pentobarbitone effect on channel conductance from 41 microM to 7.2 microM and increased maximum conductance to 72 pS. We conclude that GABAA channel conductance is related to the concentration of the allosteric agonist pentobarbitone.
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| 2. |
- Eghbali, Mansoureh, et al.
(författare)
-
Effects of propofol on GABAA channel conductance in rat-cultured hippocampal neurons.
- 2003
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Ingår i: European Journal of Pharmacology. - 0014-2999 .- 1879-0712. ; 468:2, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- Channels were activated, in ripped-off patches from rat-cultured hippocampal neurons, by propofol alone, propofol plus 0.5 microM GABA (gamma-aminobutyric acid) or GABA alone. The propofol-activated currents were chloride-selective, showed outward-rectification and were enhanced by 1 microM diazepam. The maximum propofol-activated channel conductance increased with propofol concentration from less than 15 pS (10 microM) to about 60 pS (500 microM) but decreased to 40 pS in 1 mM propofol. Fitting the data from 10 to 500 microM propofol with a Hill-type equation gave a maximum conductance of 64 pS, an EC50 value of 32 microM and a Hill coefficient of 1.1. Addition of 0.5 microM GABA shifted the propofol EC50 value to 10 microM and increased the maximum channel conductance to about 100 pS. The Hill coefficient was 0.8. The maximum channel conductance did not increase further when 1 microM diazepam was added together with a saturating propofol concentration and GABA. The results are compared to effects other drugs have on GABAA channels conductance.
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