Distribution of Na+ K(+)-ATPase in regenerating retinal pigment epithelium in the rabbit. A study by electron...

Electron microscopic cytochemistry was used to examine the distribution of the enzyme sodium potassium ATPase (Na+ K(+)-ATPase) on the plasma membrane of regenerating retinal pigment epithelium (RPE). Observations were made in rabbits that received intravenous sodium iodate, which elicits RPE degeneration followed by regeneration. A gradient in intensity and polarization of enzyme activity was observed from the least mature cells in the distal part of the regenerating epithelial sheet to more mature cells proximally. The least mature cells exhibited faint Na+ K(+)-ATPase activity over their entire plasma membrane except where it faced the basement membrane. As cells matured and re-expressed the cytologic characteristics of mature RPE, activity intensified and became localized to the apical plasma membrane, as in normal RPE. The observations show the ability of damaged RPE to recover its normal structural and functional polarity.