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690885 [2018/11/20 14:26] (current)
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 +====== gamma-Aminobutyric-acid- and pentobarbitone-gated chloride currents in internally perfused frog sensory neurones.======
 +
 +** Article date:** 1985/3/1
 +~~META:date created = 1985-03-01~~
 +
 +** PubMed ID: 690885 **
 +
 +** Journal name: The Journal of physiology (ISSN: 0022-3751) **
 +
 +** ABSTRACT **
 +
 +gamma-Aminobutyric-acid- (GABA) and pentobarbitone-induced Cl- currents (ICl) were studied in isolated frog sensory neurones after suppression of Na+, K+ and Ca2+ currents using a suction-pipette technique combining internal perfusion with voltage clamp. All GABA-sensitive neurones responded to pentobarbitone. Both GABA- and pentobarbitone-induced ICl reversed at the Cl- equilibrium potential (ECl). The dose-response curve for maxima of GABA-induced ICl was sigmoidal with a mean concentration producing a half-maximum response, Ka of 2 X 10(-5) M at a Hill coefficient of 1.8. In the presence of pentobarbitone,​ the GABA dose-response curve shifted to the left without affecting the saturating maximum current. At high concentrations,​ both GABA and pentobarbitone could also potentiate the pentobarbitone- and GABA-induced ICl respectively,​ while pre-treatment with one of the two markedly attenuated currents induced by the other, indicating a '​cross-desensitization'​. In the presence of pentobarbitone,​ the augmented response was voltage dependent and this augmentation was much greater in the inward-current direction than outward. In producing ICl, pentobarbitone and its stereoisomers were potent in the order of (-) isomer greater than (+/-) racemic mixture greater than (+) isomer. A stereospecific facilitatory action of pentobarbitone on GABA responses was also found in the same order. Responses to GABA, homotaurine,​ taurine, beta-alanine,​ 5-aminovaleric acid, (+)- and (-)-gamma-amino-beta-hydroxybutyric acid and muscimol were equally enhanced by pentobarbitone,​ though its action on glycine-induced ICl was less effective. Picrotoxin inhibited the GABA- and pentobarbitone-induced ICl from either side of membrane, while internal application of GABA and pentobarbitone did not exert any effect. It was concluded that pentobarbitone binds to the '​barbiturate receptors'​ located close to the GABA receptor-Cl- channel complex, and directly affects the GABA-GABA receptor interactions rather than the ionic channels.
 +
 +===== ===== 
 +
 +Author List: Akaike N, Hattori K, Inomata N, Oomura Y
 +
 +Publication Types: Journal Article; Research Support, Non-U.S. Gov't
 +
 +Substances mentioned in the article: Amino Acids; Chlorides; Ion Channels; Muscimol; gamma-Aminobutyric Acid; Pentobarbital; ​
 +
 +Mesh terms: Action Potentials/​drug effects; Amino Acids/​pharmacology;​ Animals; Chlorides/​physiology;​ Dose-Response Relationship,​ Drug; Drug Interactions;​ Ganglia, Spinal/​cytology;​ In Vitro Techniques; Ion Channels/​physiology;​ Muscimol/​pharmacology;​ Neurons, Afferent/​physiology;​ Pentobarbital/​pharmacology;​ gamma-Aminobutyric Acid/​pharmacology; ​
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 +Citations: ​  - //​[[4293853]]//​
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 +  - //​[[690885]]//​
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 +{{tag> Amino_Acids Pentobarbital Chlorides gamma-Aminobutyric_Acid Ion_Channels Muscimol }}
 +
 +{{keywords>​ Amino Acids, Pentobarbital,​ Chlorides, gamma-Aminobutyric Acid, Ion Channels, Muscimol}}
 +
  
690885.txt · Last modified: 2018/11/20 14:26 (external edit)