Mistry D K, Hablitz J J
Neurobiology Research Center, University of Alabama, Birmingham 35294.
Pflugers Arch. 1990 Jun;416(4):454-61. doi: 10.1007/BF00370754.
The action of gamma-aminobutyric acid (GABA) and the GABAA-receptor agonists muscimol, isoguvacine and 4,5,6,7-tetrahydroisoxazolo [5,4-c]pyridin-3-ol (THIP) were studied at the single-channel level in outside-out membrane patches from cultured chick cerebral neurons. All agonists activated channels with multiple-conductance states. The main-state conductance activated by all agonists had a value around 26 pS in symmetrical TRIS/Cl solutions. Subconductance states of around 13 pS and 18 pS were seen with application of each agonist. Muscimol and isoguvacine tended preferentially to activate subconductance states. Gating by all agonists was complex. Open-time distributions for main-state activity gated by GABA, isoguvacine and THIP were best described by the sum of two exponential curves with similar time constants. Muscimol-gated activity was best described by the sum of three exponentials indicating the presence of an additional longer open state. These results indicate that certain GABAA-receptor agonists are capable of preferentially activating subconductance states.
在培养的鸡脑神经元的外翻膜片上，于单通道水平研究了γ-氨基丁酸（GABA）以及GABAA受体激动剂蝇蕈醇、异鹅膏蕈氨酸和4,5,6,7-四氢异恶唑并[5,4-c]吡啶-3-醇（THIP）的作用。所有激动剂均激活具有多种电导状态的通道。在对称的TRIS/Cl溶液中，所有激动剂激活的主要状态电导值约为26 pS。施加每种激动剂时，可观察到约13 pS和18 pS的亚电导状态。蝇蕈醇和异鹅膏蕈氨酸倾向于优先激活亚电导状态。所有激动剂的门控都很复杂。由GABA、异鹅膏蕈氨酸和THIP门控的主要状态活动的开放时间分布，用具有相似时间常数的两条指数曲线之和来描述最为合适。蝇蕈醇门控的活动用三条指数曲线之和来描述最为合适，这表明存在一个额外的较长开放状态。这些结果表明，某些GABAA受体激动剂能够优先激活亚电导状态。
