Screening the candidates of the Ca²⁺-activated K⁺ channels by immunohistochemistry. (A) Co-labeling results of the BK (red) and PKC-α (green) antibodies in the retinal slice. The BK was detected in the inner segment (IS), outer plexiform layer (OPL), upper and lower portions of the inner nuclear layer (INL), and ganglion cells (GC). The BK was not co-localized with PKC-α. B. Co-labeling results of the SK1 (red) and PKC-α (green) antibodies in the retinal slice. The SK1 was detected in the lower portion of the INL, ganglion cell (GC), and weakly in the IS. The SK1 was not co-localized with the PKC-α. (C-D) Co-labeling results of the SK2 (red) or SK3 (red) with PKC-α (green) antibodies in the retinal slice. Both SK2 (C) and SK3 (D) were mainly detected in the GC, and both were not co-localized with PKC-α. E. Co-labeling results of the IK (red) and PKC-α (green) antibodies in the retinal slice. The IK (Alomone) was detected in the OPL, upper portion of the INL, IPL, and GC. The IK detected in the upper portion of the INL and innermost layer of the IPL was co-labeled by PKC-α. Co-labeled rod bipolar cells were marked by asterisk (*, white), and inset view of the yellow box were presented in the down row. *Scale bar = 20 μm.