Feedback effects of horizontal cell membrane potential on cone calcium currents studied with simultaneous recordings

被引:61
作者
Cadetti, L
Thoreson, WB
机构
[1] Univ Nebraska, Med Ctr, Dept Ophthalmol & Visual Sci, Omaha, NE 68198 USA
[2] Univ Nebraska, Med Ctr, Dept Pharmacol & Expt Neurosci, Omaha, NE 68198 USA
关键词
D O I
10.1152/jn.01042.2005
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Horizontal cell (HC) to cone feedback helps establish the center-surround arrangement of visual receptive fields. It has been shown that HC activity influences cone synaptic output by altering the amplitude and voltage dependence of the calcium current (I-Ca) in cones. In this study, we obtained voltage-clamp recordings simultaneously from cones and HCs to directly control the membrane potential of HCs and thereby measure the influence of HC membrane potential changes on I-Ca in adjacent cones. Directly hyperpolarizing voltage clamped HCs produced a negative activation shift and increased the amplitude of I-Ca in cones. Both of these effects were abolished by enhancing extracellular pH buffering capacity with HEPES. In contrast, addition of the gap junction blocker, carbenoxolone, did not significantly alter the shifts or amplitude changes in cone I-Ca produced by changes in HC membrane potential. These results support the hypothesis that changes in the HC membrane potential alter the voltage dependence and amplitude of cone I-Ca by altering extracellular pH levels at the synapse.
引用
收藏
页码:1992 / 1995
页数:4
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