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Science. 2001 May 11;292(5519):1178-80.

Hemichannel-mediated inhibition in the outer retina.

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Research Unit Retinal Signal Processing, The Netherlands Ophthalmic Research Institute, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.


An essential feature of the first synapse in the retina is a negative feedback pathway from horizontal cells to cones. Here we show that at this synapse, connexin26 forms hemichannels on horizontal cell dendrites near the glutamate release site of the cones. Blocking these hemichannels hyperpolarizes horizontal cells, modulates the Ca2+ channels of the cones, and abolishes all feedback-mediated responses. We propose a feedback mechanism in which the activity of the Ca2+ channels and the subsequent glutamate release of the cones are modulated by a current through these hemichannels. Because the current through the hemichannels depends on the polarization of the horizontal cells, their activity modulates the output of the cones.

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