%0 Journal Article %A Tamiya, Shigeo %A Dean, William L. %A Paterson, Christopher A. %A Delamere, Nicholas A. %T Regional Distribution of Na,K-ATPase Activity in Porcine Lens Epithelium %B Investigative Ophthalmology & Visual Science %D 2003 %R 10.1167/iovs.03-0287 %J Investigative Ophthalmology & Visual Science %V 44 %N 10 %P 4395-4399 %@ 1552-5783 %X purpose. It has been established that Na,K-ATPase activity is higher in lens epithelium than fibers. However, others have suggested the Na,K-ATPase enzyme may be inactive or absent in the central 10% of the epithelium. Studies were conducted to measure and compare Na,K-ATPase specific activity and to examine Na,K-ATPase protein expression in the anterior and equatorial regions of porcine lens epithelium. methods. Na,K-ATPase activity was determined by measuring the ouabain-sensitive rate of adenosine triphosphate (ATP) hydrolysis. Western blot analysis was used to detect Na,K-ATPase catalytic subunit (α) and glycoprotein subunit (β) protein as well as β-actin which was used as a loading control. results. Na,K-ATPase specific activity was more than two times higher in the equatorial epithelium than the anterior 50% of the epithelium. However, the abundance of Na,K-ATPase α1 isoform protein was similar in the two regions. Neither the α2 nor α3 Na,K-ATPase isoform could be detected in the anterior or equatorial epithelium, but Na,K-ATPase β1 protein was detected in both regions. In contrast to the observed regional difference in Na,K-ATPase activity, the activity of a different P-type ATPase, plasma membrane Ca-ATPase (PMCA), was not significantly different in the anterior and central epithelium. Western blot analysis indicated the presence of two PMCA isoforms, PMCA2, and PMCA4. conclusions. Na,K-ATPase activity is significantly higher at the equatorial region of the epithelium compared with the anterior, even though the level of Na,K-ATPase protein is similar in the two regions. It is possible that nonuniform distribution of functional Na,K-ATPase activity contributes to the driving force for circulating solute movement through the lens fiber mass. %[ 3/1/2021 %U https://doi.org/10.1167/iovs.03-0287