Heme oxygenase-2 isozyme is the predominant form of heme oxygenase in
rat brain by western blot analysis. Heme oxygenase-1 isozyme is not in
duced by light adaptation in rat retina by western blot analysis. Immu
nocytochemistry localizes heme oxygenase-2 in three areas of the retin
a: the retinal pigment epithelium, inner segment and external nuclear
layers of the rat retina. Ganglion cells and cell bodies of the intern
al nuclear layer of the retina and Muller cells were largely unstained
for heme oxygenase-2. The localization of heme oxygenase-2 in the ret
ina implies that its function is not associated with phototransduction
. Also, light adaptation does not appear to induce heme oxygenase-1, a
measure of oxidative injury.