Retinal Regulation

Science's STKE  15 May 2001:
Vol. 2001, Issue 82, pp. tw8
DOI: 10.1126/stke.2001.82.tw8

The horizontal cells in the outer plexiform layer of the retina generate the surround inhibition for the bipolar cells, but the underlying mechanism has remained elusive. Kamermans et al. show that there are gap junction hemichannels at synapses between horizontal cells and cone photoreceptors. Blockade of these hemichannels by carbenoxolone causes horizontal-cell hyperpolarization and disrupts feedback responses in cones and horizontal cells. This finding suggests the existence under physiological conditions of a negative-feedback mechanism from horizontal cells to cones through an electrical or ephatic mechanism.

M. Kamermans, I. Fahrenfort, K. Schultz, U. Janssen-Bienhold, T. Sjoerdsma, R. Weiler, Hemichannel-mediated inhibition in the outer retina. Science 292, 1178-1180 (2001). [Abstract] [Full Text]