title: Comparison of GABA analogues at the crayfish stretch receptor neurone.
abstract: The conductance increase induced by GABA and structurally related compounds has been measured in voltage clamped stretch receptor neurones of crayfish. GABA induced only at 10(-3) M a rapid conductance increase. The response to lower concentrations between 10(-6) and 10(-4) M developed slowly (20-60 min). The postsynaptic conductance increase induced by repetitive application of the same GABA concentration was progressively enhanced in the speed and magnitude. In the presence of nipecotic acid or in Na+-free Ringer solutions, the response to all GABA concentrations was instantaneous and constant for each concentration. Muscimol between 10(-6) and 10(-3) M caused instantaneous dose-dependent conductance increases. These results suggest the presence of a saturable GABA uptake system limiting the access of bath applied GABA, but not of muscimol, to postsynaptic receptor sites.
mesh_terms: D000818:Animals; D003400:Astacoidea; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D007555:Isoxazoles / Q000494:pharmacology; D008465:Mechanoreceptors / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D009118:Muscimol / Q000494:pharmacology; D009557:Nipecotic Acids / Q000494:pharmacology; D011392:Proline / Q000031:analogs & derivatives*; D012964:Sodium / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D007555:Isoxazoles; D009557:Nipecotic Acids; C030278:nipecotic acid; D009118:Muscimol; D005680:gamma-Aminobutyric Acid; C017984:progabide acid; D011392:Proline; D012964:Sodium; C010983:homoproline; C015542:gaboxadol