Akhondzadeh S, Stone T W
Department of Pharmacology, University of Glasgow, Scotland, UK.
Brain Res. 1994 Dec 5;665(2):229-36. doi: 10.1016/0006-8993(94)91342-0.
Extracellular recordings were made from the CA1 pyramidal cell layer of hippocampal slices in response to stimulation of Schaffer collateral fibres in stratum radiatum. Adenosine and muscimol induced concentration-dependent reductions in the amplitude of orthodromically induced population potentials. In order to eliminate effects of these agents on potassium channels, experiments were performed in the presence of barium, 1 mM. This concentration increased potential size, and reduced the inhibitory effect of adenosine on population spike size, but not synaptic potential size. This profile is consistent with the blockade of potassium channels associated only with the postsynaptic effects of adenosine. Muscimol responses were unaffected. Adenosine potentiated the ability of muscimol to inhibit evoked potentials in the absence or presence of barium. The potentiation was prevented by the A1 selective antagonist 8-cyclopentyltheophylline. The effects of adenosine as well as muscimol were reduced by the chloride channel blockers DIDS, which also prevented the adenosine potentiation of muscimol. The results indicate the ability of adenosine to operate chloride channels in hippocampal neurones, and suggest a potentiative interaction between adenosine and muscimol which may also involve chloride channels.
通过对海马切片CA1锥体细胞层进行细胞外记录，以响应辐射层中Schaffer侧支纤维的刺激。腺苷和蝇蕈醇可引起顺向诱导群体电位幅度的浓度依赖性降低。为了消除这些药物对钾通道的影响，实验在1 mM钡存在的情况下进行。该浓度增加了电位大小，并降低了腺苷对群体峰电位大小的抑制作用，但对突触电位大小没有影响。这种情况与仅与腺苷的突触后效应相关的钾通道阻断一致。蝇蕈醇的反应不受影响。在不存在或存在钡的情况下，腺苷增强了蝇蕈醇抑制诱发电位的能力。A1选择性拮抗剂8-环戊基茶碱可阻止这种增强作用。氯化物通道阻滞剂DIDS降低了腺苷以及蝇蕈醇的作用，这也阻止了腺苷对蝇蕈醇的增强作用。结果表明腺苷能够作用于海马神经元中的氯化物通道，并提示腺苷与蝇蕈醇之间可能存在增强性相互作用，这也可能涉及氯化物通道。
