Horizontal cells of the rat retina are resistant to degenerative processes induced by ischemia-reperfusion.

The fate of calbindin D28k (calbindin)-labeled horizontal cells in the ischemic rat retina induced by increasing intraocular pressure was investigated by immunocytochemistry using an antiserum against calbindin. In the normal retina, strong calbindin-like immunoreactivity was seen in the horizontal cells, and the density of the labelled horizontal cells was 815.3+/-15.2 per mm2. The thickness of the treated retina became progressively thinner with increasing reperfusion time after the ischemic insult due to a loss of retinal cells in the inner and outer nuclear layers. However, the densities of the horizontal cells per mm2 were 814.0+/-26.4 at 1 week, 813.3+/-20.8 at 2 weeks, and 812.6+/-11.5 at 4 weeks, indicating that horizontal cells did not degenerate during experimental periods. Thus, calbindin may have a protective role for horizontal cells to ischemic insult by its ability to buffer calcium influx in the rat retina.